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Factors affecting the complexity of dental implant restoration – what is the current evidence and guidance?
Abstract
Objectives The aim of this paper is to identify the factors that affect the complexity of implant restoration and to explore
the indices that help us to assess it. With this knowledge the growing number of clinicians restoring dental implants will
have a better understanding of the available guidance and evidence base, and the differing levels of competence required. Study design A literature review was conducted. The selection of publications reporting on complexity was based on predetermined criteria and was agreed upon by the authors. After title and abstract screening 17 articles were reviewed. The articles that were utilised to form the ITI SAC tool and Cologne Risk Assessment we also included. Assessing complexity Two key guides are available: International Team for Implantology’s Straight-forward Advanced Complex tool4 and the Cologne
ABC risk score.5 While these guides help identify treatment complexity they do not provide a strong enough evidence base from which to solely base clinical decisions. The key patient factors are expectation, communication, the oral environment, aesthetic outcome, occlusion, soft tissue pro le and the intra-arch distance, whereas the key technical factors are impression taking, type of retention, loading protocol and the need for provisional restorations. Human factors also have a signi cant effect on complexity, speci cally, the experience and training of the clinician, team communication and the work environment. Conclusions There are many interconnecting factors that affect the complexity of dental implant restoration. Furthermore the two widely used indices for the assessment of complexity have been investigated, and although these offer a good guideline
as to the level of complexity, there is a lack evidence to support their use. The development of evidence-based treatment and protocols is necessary to develop the current indices further, and these need to be expanded to include other critical areas, such as human factors. A practical guide to aid practitioners in reducing complexity has been proposed.
... The use of screw retention allows rapid reversibility in case of removal to control or solve complications. On the other hand, the screw channel compromises the stiffness of the material, leading to an increased fracture probability [34]. Cemented prostheses have some advantages compared to screw-retained implant prostheses when the issue of reversibility is not considered. ...
... Cemented prostheses have some advantages compared to screw-retained implant prostheses when the issue of reversibility is not considered. These prostheses have a better passive fit and are easy to adjust in the presence of tensions, thus allowing better passivity [34,35]. In some cases, it is difficult to justify using screws to retain prostheses, except for limited abutment height where there is a diminished surface area for cementation, or in abutments with a subgingival margin where removal of abutments could be complicated when trying to check extravasated cementing material. ...
... In some cases, it is difficult to justify using screws to retain prostheses, except for limited abutment height where there is a diminished surface area for cementation, or in abutments with a subgingival margin where removal of abutments could be complicated when trying to check extravasated cementing material. The cemented system can facilitate the insertion of prostheses in areas with insufficient mouth opening [34,35]. ...
Citation: Vozzo, L.M.; Azevedo, L.; Fernandes, J.C.H.; Fonseca, P.; Araújo, F.; Teixeira, W.; Fernandes, G.V.O.; Correia, A. The Success and Complications of Complete-Arch Implant-Supported Fixed Monolithic Zirconia Restorations: A Systematic Review. Prosthesis 2023, 5, 425-436. Abstract: In full-arch rehabilitation with implant-supported fixed prostheses, using monolithic zirconia seems to have several advantages regarding function and esthetics. However, the current scientific evidence is still limited. Thus, the aim of this investigation was to systematically review the literature on monolithic zirconia restorations for full-arch rehabilitation, particularly pursuing the survival rate and mechanical and biological complications. This study's protocol was registered in PROSPERO (CRD42022301799). The primary literature search was performed in PubMed/MedLine and Web of Science, and a manual search was performed (checking cross-references). The focused question was, "In an adult population with one or both edentulous arches (P), the oral rehabilitation with implant-supported fixed-monolithic zirconia (full arch) (I), compared with oral rehabilitation using fixed-metal-ceramic prosthesis on implants (C), did show superior clinical results (O) in a minimum follow-up of 1 year (T)?" Inclusion and exclusion criteria were defined. Joana Briggs Institute tools were used to evaluate the quality of the studies. Meta-analysis was performed for the variable survival rate (%), applying the specific continuous moderator (follow-up). Data heterogeneity (I 2) was assessed. From the initial search, 327 references were obtained. After eliminating duplicates and applying the inclusion/exclusion criteria by reading the titles, abstracts, and full text, seven articles were included. All included articles were observational longitudinal retrospective studies, with a number of prostheses between 7 and 2039. The mean age was 60 years, and the mean follow-up was 49.7 months. They had mandibular, maxillary, or bimaxillary rehabilitations, always with screw-retained retention, with an average survival rate of 97.23%. The number of implants ranged between four and eight. The quality of the articles was over 70%, and the heterogeneity was considered low (I 2 = 28.64%). Within a mean follow-up of around four years, full-arch implant-supported monolithic zirconia rehabilitations had a high survival rate and minimal complications.
... Clinicians are currently focusing on factors that influence the success rate of classical and implant-prosthetic prosthetic treatments: biomaterials, design and surface bioactivity of dental implants, biomechanical factors, quality and volume of bone tissue, surgical technique. Decisions regarding the selection of techniques and materials used in prosthetic and implant therapy imply uncertainties regarding the prognosis of therapy, in relation to the experience and preferences of the practitioner, the preferences and values of patients, and the costs involved (14). The long-term success of the mucosal support reconstruction techniques is highly related to the individualized analysis of the specific systemic, loco-regional, local parameters and the focus on therapeutic algorithms adapted to each individual case. ...
... As bone quality in the upper jaw is inferior to that in the lower jaw, the success rate of upper jaw implants has tended to be low, and lateral force from the IOD is associated with an increased risk of implant removal [24]. When International Team for Implantology (ITI)'s Straightforward, Advanced, Complex (SAC) classification tool (Basel, Switzerland) is used, just because it is the maxillary IOD, it is classified as Comprehensive in the SAC classification of ITI [25]. Furthermore, in the distal part of the upper jaw, there are cases where implant placement is difficult due to the maxillary sinus [26]. ...
The recent literature on maxillary implant overdenture (IOD) was reviewed in order to clarify its predictability and establish treatment guidelines. Electronic searches were performed using PubMed, and articles about maxillary IOD written after 1990 were reviewed, focusing on the following items: I. implant survival rate, II. maxillary IOD survival rate, III. number of implants, IV. attachment type, V. follow-up period, VI. implant system, and VII. opposing dentition. The review revealed an implant survival rate of 61-100% and an overdenture survival rate of 72.4-100%. The attachments used included bars, balls, locators, and telescope crowns. The minimum and maximum observation periods were 12 months and 120 months, respectively, and the number of implants used for supporting IOD ranged from 2 to 8. At present, there is no strong evidence to indicate that maxillary IOD is clearly superior for all the items examined. However, the existing data indicate that maxillary IOD has almost the same therapeutic effect as fixed implant superstructures, and is a treatment option that can be actively adopted for patients in whom fixed superstructures cannot be applied for various reasons.
... It seems that the evidence of overloadingdental implantsleading to hard and/or soft tissue defects is very scarce [50,51].There is evidence from observational studies that patients exhibiting poor plaque control and not attending regular periodontal maintenance visits are at higher risk of developing peri-implantitis, but overload alone, as the etiologyof bone loss in humans, remains nuclear [52]. Nevertheless, another study suggested that even when implant-prosthetic characteristics play a protective role; e.g. the use of screw-retained instead of a cement-retained prosthesis, there is a higher marginal bone loss observed under inappropriate occlusal patterns, such as inadequate anterior and canine guidances or inadequate occlusal contacts [53]. ...
n this literature review relevant published studies were searched for in PubMed, from 2015 to 2020. It was concluded that DTM and NCCLs are multifactorial diseases, of which occlusion is not a causative factor; in addition to the biological failures of dental implants. However, regarding the mechanical failures of dental implants, occlusion can be considered a causative factor.
... To take the most strategic therapeutic decision, some authors [14] have determined the criteria to be measured: reduction of morbidity and the number of procedures, Znancial considerations, predictability of healing, and healing time. ...
Introduction
The aim of this study is to assess a pioneering technique for atrophic premaxilla restoration. The objective is to reposition an implant reconstruction zone into a position both anatomically and physiologically suitable for occlusal function. Indeed, unlike the other few articles published on the correctional osteotomy of the implant in an inadequate situation, we have planned here an initially « unsuitable » insertion in order to benefit of the available bone mass.
Material and method
3 patients aged 14 to 20 years old (1 woman and 2 men) were operated on at the maxillo-facial department of Lille 2 University Hospital for partial implant-prosthetic rehabilitation on atrophic maxillary and/or mandibular sector.
13 implants were seated (85% in the maxilla) in the native bone then moved subsequently by segmental osteotomy.
Results
The patients were assessed both clinically and radiologically according to the functional and aesthetic criteria of implant-prosthetic restoration.
Functionally, a biomechanically favourable implant/number of teeth ratio (80%) was achieved, with consistent occlusal relationships (centric positioning of the midline point and absence of crossbite) in 100% of cases. Aesthetically, the screw access hole is systematically non-apparent (100%) but has a prosthetically substituted reduced gingivo-alveolar architecture.
Discussion
These observations suggest that implant repositioning with segmental osteotomy allows for atrophic premaxilla restoration in implanted bone volume whatever the initial angulation.
Peri-implant aesthetic difficulties are not specific to the technique suggested here but are quite common to all premaxilla reconstruction techniques.
Lastly, this group of three patients is not enough to be conclusive, and a larger group would be necessary to validate this type of management.
... In addition to selected reports, a sizable number of excellent reviews, systematic reviews, and clinical descriptive materials were also published on topics of prosthodontic interest. Although commenting in detail on this additional material is impossible, it is listed here for those interested in practice guidelines, [1][2][3][4] anatomy and physiology, [5][6][7] bruxism, 8,9 conventional removable complete prosthodontics, [10][11][12][13] conventional fixed prosthodontics, [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] conventional removable partial prosthodontics, 32 diagnostics, 33,34 digital dentistry, [35][36][37] esthetics, [38][39][40][41][42][43][44][45] evidence-based dentistry, [46][47][48] general topics in implant dentistry, [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66] general topics in prosthodontics, [67][68][69][70] geriatric dentistry, [71][72][73][74][75][76][77][78] implant-fixed prosthodontics, [79][80][81][82][83][84][85][86] implant-removable prosthodontics, [87][88][89][90] implant site development, [91][92][93][94][95] implant surgery, [96][97][98][99][100][101][102][103][104] implant treatment planning considerations, [105][106][107][108][109][110][111][112][113][114][115][116] maintenance, [117][118][119][120][121] material science, [122][123][124][125][126][127] maxillofacial prosthetics, [128][129][130] occlusion, [131][132][133][134][135][136] pathology and disease, [137][138][139][140][141][142][143][144][145] pharmacology, [146][147][148][149][150][151][152][153][154][155][156][157][158][159][160][161] radiology, [162][163][164] restorative successsurvival, [165][166][167][168][169][170][171] tooth structure loss and restoration, [172][173][174][175][176][177][178][179][180][181][182] and xerostomia. 183 General prosthodontic considerations Accurate transfer of condylar guidance controls from the patient to an articulator is important prior to laboratory fabrication of indirect occlusal restorations. ...
This review was conducted to assist the busy dentist in keeping abreast of the latest scientific information regarding the clinical practice of dentistry. Each of the authors, who are considered experts in their disciplines, was asked to peruse the scientific literature in their discipline published in 2016 and review the articles for important information that may affect treatment decisions. Comments on experimental methodology, statistical evaluation, and the overall validity of conclusions are included with many of the reviews. The reviews are not meant to stand alone but are intended to inform the interested reader about what has been discovered in the past year. The readers are then invited to go to the source, if they want more detail.
Understanding patient desires during prosthodontic management in the general practice setting may be challenging. Careful recognition of the clues from the patient in the initial few appointments will ease the subsequent treatment for both the dentist and the patient. This article discusses treatment choices in dentistry and how to tailor them to individual patients.
CPD/Clinical Relevance: Potential difficult clinical situations can be managed effectively if identified at the earlier stages of meeting with a patient. Therefore, initial consultation appointments are important as a prognostic tool in prosthodontics/restorative treatment planning.
The placement of dental implants in the anterior maxilla is a challenge for clinicians because of patients' exacting esthetic demands and difficult pre-existing anatomy. This article presents anatomic and surgical considerations for these demanding indications for implant therapy. First, potential causes of esthetic implant failures are reviewed, discussing anatomic factors such as horizontal or vertical bone deficiencies and iatrogenic factors such as improper implant selection or the malpositioning of dental implants for an esthetic implant restoration. Furthermore, aspects of preoperative analysis are described in various clinical situations, followed by recommendations for the surgical procedures in single-tooth gaps and in extended edentulous spaces with multiple missing teeth. An ideal implant position in all 3 dimensions is required. These mesiodistal, apicocoronal, and orofacial dimensions are well described, defining "comfort" and "danger" zones for proper implant position in the anterior maxilla. During surgery, the emphasis is on proper implant selection to avoid oversized implants, careful and low-trauma soft tissue handling, and implant placement in a proper position using either a periodontal probe or a prefabricated surgical guide. If missing, the facial bone wall is augmented using a proper surgical technique, such as guided bone regeneration with barrier membranes and appropriate bone grafts and/or bone substitutes. Finally, precise wound closure using a submerged or a semi-submerged healing modality is recommended. Following a healing period of between 6 and 12 weeks, a reopening procedure is recommended with a punch technique to initiate the restorative phase of therapy.
A significant cause of mistakes in healthcare and which are potentially harmful or fatal to patients can result from both individual clinicians and their employing organisations. The understanding and recognition of the role of human error within the healthcare setting is improving, but we still have much to learn when compared with other high‐risk organisations such as aviation where such errors can be devastating at a much larger scale.
The importance of both organisational issues and human factor issues at a more personal level including tiredness, the effect of emotions and the role of situational awareness, needs to be understood by all those involved in healthcare. Potential mistakes can be reduced with simple measures which need to be recognised by, emphasised and embedded in both teams and individuals.
In this review, we address the need for greater awareness of human factors, assessing the path to error and how this can be reduced to minimum levels in clinical practice.
To systematically review changes in mucosal soft tissue thickness and keratinised mucosa width after soft tissue grafting around dental implants.
An electronic literature search was conducted of the MEDLINE database published between 2009 and 2014. Sequential screenings at the title, abstract, and full-text levels were performed. Clinical human studies in the English language that had reported changes in soft tissue thickness or keratinised mucosa width after soft tissue grafting at implant placement or around a present implant at 6-month follow-up or longer were included.
The search resulted in fourteen articles meeting the inclusion criteria: Six of them reported connective tissue grafting around present dental implants, compared to eight at the time of implant placement. Better long-term soft tissue thickness outcomes were reported for soft tissue augmentation around dental implants (0.8-1.4 mm), compared with augmentation at implant placement (-0.25-1.43 mm). Both techniques were effective in increasing keratinised tissue width: at implant placement (2.5 mm) or around present dental implants (2.33-2.57 mm).
The present systematic review discovered that connective tissue grafts enhanced keratinised mucosa width and soft tissue thickness for an observation period of up to 48 months. However, some shrinkage may occur, resulting in decreases in soft tissue, mostly for the first three months. Further investigations using accurate evaluation methods need to be done to evaluate the appropriate time for grafting.
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Purpose:
This systematic review aimed to identify different prosthodontic outcomes between screw- and cement-retained implant prostheses.
Materials and methods:
The relevant articles were retrieved from the following electronic databases: MEDLINE, EMBASE, PubMed (using medical subject headings), and the Cochrane Central Register of Controlled Trials (CENTRAL). The search was performed up to December 31, 2013, and was restricted to studies on human subjects reported in English. A further search was conducted through the reference lists of the articles found as well as from early online articles. Reviewed studies were those on fixed implant prostheses using different retention mechanisms such as screws or cement. Information on types of screws and mechanisms of preloading, as well as different luting cements, was collected in correlation with prosthodontic maintenance/complication issues seen in the clinical studies.
Results:
Sixty-two papers met the review criteria. There were only six randomized controlled trials and none of them included an equivalent number of screw- and cement-retained single implant crowns for comparison. Studies used different types of screws and only a few reported the preloading procedure for the prosthetic screws. Other studies involving cement-retained implant prostheses used a range of dental cements; however, some did not specify the type used. Studies reported various prosthodontic maintenance/complication issues such as screw loosening, porcelain fracture, loss of retention, and esthetic concerns. Five studies did not report any prosthodontic maintenance issues during their observation periods. More recent studies also did not report any incidence of screw loosening. Only two studies stated the standardized criteria for reporting their prosthodontic maintenance/ complication issues.
Conclusions:
With inadequate information and various study designs, it was difficult to compare the prosthodontic outcomes between screw and cement-retained fixed implant prostheses. Both retention mechanisms showed prosthodontic maintenance/complication issues that must be considered and this review showed that the introduction of newer implant components may assist in minimizing these issues. It is also recommended that standardized criteria be used when reporting prosthodontic maintenance/complication issues to allow better comparison of data.
This report was prepared for WHO Patient Safety’s Methods and Measures for Patient Safety Working Group.
It provides a basic description of major topic areas relating to human factors relevant to patient safety, with some indication of possible tools that can be used in a healthcare workplace for measurement or training of these topics.
First an explanation of the human factors approach is provided. An organizing framework is presented to provide a structure for the discussion of the topics, by categorizing them as follows:
i) Organizational/ Managerial, ii) Team, iii) Individual, iv) Work
environment.
Wider social factors and the central role of the patient are also acknowledged but these aspects of the healthcare system are not explicitly covered.
Ten topic areas within these four categories are described: organizational culture, managerial leadership, communication, teamwork, team leadership, situation awareness, decision making, stress, fatigue, work environment.
A selection of tools for education, measurement or training these human factors topics is described. Some of these may be suitable for application in developing, as well as developed, countries.
Purpose:
To compare the accuracy of digital and conventional impression techniques for partially and completely edentulous patients and to determine the effect of different variables on the accuracy outcomes.
Materials and methods:
An electronic and manual search was conducted to identify studies reporting on the accuracy of implant impressions. Pooled data were descriptively analyzed. Factors affecting the accuracy were identified, and their impact on accuracy outcomes was assessed.
Results:
The 76 studies that fulfilled the inclusion criteria featured 4 clinical studies and 72 in vitro studies. Studies were grouped according to edentulism; 41 reported on completely edentulous and 35 on partially edentulous patients. For completely edentulous patients, most in vitro studies and all three clinical studies demonstrated better accuracy with the splinted vs the nonsplinted technique (15 studies, splint; 1, nonsplint; 9, no difference). One clinical study and half of the in vitro studies reported better accuracy with the open-tray vs the closed-tray technique (10 studies, open-tray; 1, closed-tray; 10, no difference). For partially edentulous patients, one clinical study and most in vitro studies showed better accuracy with the splinted vs the nonsplinted technique (8 studies, splint; 2, nonsplint; 3, no difference). The majority of in vitro studies showed better accuracy with the open-tray vs the closed-tray technique (10 studies, open-tray; 1, closed-tray; 7, no difference), but the only clinical study reported no difference.
Conclusion:
The splinted impression technique is more accurate for both partially and completely edentulous patients. The open-tray technique is more accurate than the closed-tray for completely edentulous patients, but for partially edentulous patients there seems to be no difference. The impression material (polyether or polyvinylsiloxane) has no effect on the accuracy. The implant angulation affects the accuracy of implant impressions, while there are insufficient studies for the effect of implant connection type. Further accuracy studies are needed regarding digital implant impressions.
Purpose:
To assess the survival outcomes and reported complications of screw- and cement-retained fixed reconstructions supported on dental implants.
Materials and methods:
A Medline (PubMed), Embase, and Cochrane electronic database search from 2000 to September 2012 using MeSH and free-text terms was conducted. Selected inclusion and exclusion criteria guided the search. All studies were first reviewed by abstract and subsequently by full-text reading by two examiners independently. Data were extracted by two examiners and statistically analyzed using a random effects Poisson regression.
Results:
From 4,324 abstracts, 321 full-text articles were reviewed. Seventy-three articles were found to qualify for inclusion. Five-year survival rates of 96.03% (95% confidence interval [CI]: 93.85% to 97.43%) and 95.55% (95% CI: 92.96% to 97.19%) were calculated for cemented and screw-retained reconstructions, respectively (P = .69). Comparison of cement and screw retention showed no difference when grouped as single crowns (I-SC) (P = .10) or fixed partial dentures (I-FDP) (P = .49). The 5-year survival rate for screw-retained full-arch reconstructions was 96.71% (95% CI: 93.66% to 98.31). All-ceramic reconstruction material exhibited a significantly higher failure rate than porcelain-fused-to-metal (PFM) in cemented reconstructions (P = .01) but not when comparing screw-retained reconstructions (P = .66). Technical and biologic complications demonstrating a statistically significant difference included loss of retention (P ≤ .01), abutment loosening (P ≤ .01), porcelain fracture and/or chipping (P = .02), presence of fistula/suppuration (P ≤ .001), total technical events (P = .03), and total biologic events (P = .02).
Conclusions:
Although no statistical difference was found between cement- and screw-retained reconstructions for survival or failure rates, screw-retained reconstructions exhibited fewer technical and biologic complications overall. There were no statistically significant differences between the failure rates of the different reconstruction types (I-SCs, I-FDPs, full-arch I-FDPs) or abutment materials (titanium, gold, ceramic). The failure rate of cemented reconstructions was not influenced by the choice of a specific cement, though cement type did influence loss of retention.
Background
Interest in human factors has increased across healthcare communities and institutions as the value of human centred design in healthcare becomes increasingly clear. However, as human factors is becoming more prominent, there is growing evidence of confusion about human factors science, both anecdotally and in scientific literature. Some of the misconceptions about human factors may inadvertently create missed opportunities for healthcare improvement.
Methods
The objective of this article is to describe the scientific discipline of human factors and provide common ground for partnerships between healthcare and human factors communities.
Results
The primary goal of human factors science is to promote efficiency, safety and effectiveness by improving the design of technologies, processes and work systems. As described in this article, human factors also provides insight on when training is likely (or unlikely) to be effective for improving patient safety. Finally, we outline human factors specialty areas that may be particularly relevant for improving healthcare delivery and provide examples to demonstrate their value.
Conclusions
The human factors concepts presented in this article may foster interdisciplinary collaborations to yield new, sustainable solutions for healthcare quality and patient safety.
To systematically appraise the impact of mechanical/technical risk factors on implant-supported reconstructions.
A MEDLINE (PubMed) database search from 1966 to April 2008 was conducted. The search strategy was a combination of MeSH terms and the key words: design, dental implant(s), risk, prosthodontics, fixed prosthodontics, fixed partial denture(s), fixed dental prosthesis (FDP), fixed reconstruction(s), oral rehabilitation, bridge(s), removable partial denture(s), overdenture(s). Randomized controlled trials, controlled trials, and prospective and retrospective cohort studies with a mean follow-up of at least 4 years were included. The material evaluated in each study had to include cases with/without exposure to the risk factor.
From 3,568 articles, 111 were selected for full text analysis. Of the 111 articles, 33 were included for data extraction after grouping the outcomes into 10 risk factors: type of retentive elements supporting overdentures, presence of cantilever extension(s), cemented versus screw-retained FDPs, angled/angulated abutments, bruxism, crown/implant ratio, length of the suprastructure, prosthetic materials, number of implants supporting an FDP, and history of mechanical/technical complications.
The absence of a metal framework in overdentures, the presence of cantilever extension(s) > 15 mm and of bruxism, the length of the reconstruction, and a history of repeated complications were associated with increased mechanical/technical complications. The type of retention, the presence of angled abutments, the crown-implant ratio, and the number of implants supporting an FDP were not associated with increased mechanical/technical complications. None of the mechanical/technical risk factors had an impact on implant survival and success rates.
The aim of this review was to determine the effect of several potential local risk factors on implant survival and success (primary outcomes) as well as on mucosal recession, bleeding on probing, and proximal marginal bone loss (secondary outcomes).
A comprehensive review of the literature was conducted. The selection of publications reporting on human clinical studies was based on predetermined inclusion criteria and was agreed upon by three reviewers. After title and abstract screening of 2,681 publications obtained from the search, 19 articles were deemed to be relevant to the topic and the search criteria.
Limited data show that when an implant is placed within 3 mm of the neighboring tooth, proximal bone is at risk. The data regarding the placement of implants into infected sites are still insufficient, but studies have shown that this may be possible. Soft tissue thickness has not been shown to be a risk factor in implant survival. There is also no evidence to support a relationship between the width of keratinized tissue and implant survival. No studies were found that directly related bone density to implant survival. Implant stability was also difficult to examine due to the lack of validated stability measures.
One critical factor that faced the group during the review of the literature and interpretation of the data was the multifactorial nature of implant therapy. This makes isolation of specific risk factors difficult. Conclusions are limited by the current lack of quality clinical trials in this area.
Implant-supported restorations can be secured to implants with screws (screw-retained), or they can be cemented to abutments which are attached to implants with screws (cement-retained). This literature review discusses the advantages and disadvantages of each method of retention from different aspects. These aspects include: ease of fabrication and cost, esthetics, access, occlusion, retention, incidence of loss of retention, retrievability, clinical prosthesis fit, restriction of implant position, effect on peri-implant tissue health, provisionalization, immediate loading, impression procedures, porcelain fracture, and clinical performance. Peer-reviewed literature published in the English language between 1955 and 2010 was reviewed using PubMed and hand searches. Since the choice of using either method of retention is still controversial, this review article offers some clinical situations that prefer one method of retention over the other. The review demonstrated that each method of retention has certain advantages and disadvantages; however, there are some clinical situations in which it is better to select one method of retention rather than the other.
Proposing to place endosseous implants is an integral facet of dental treatment plans. Their insertion is usually associated with a low incidence of untoward events. However, despite careful planning, surgical complications can arise: infection, intraoral hemorrhage, wound dehiscence, postoperative pain, lack of primary implant stability, inadvertent penetration into the maxillary sinus or nasal fossa, sinus lift sequelae, neurosensory disturbances, injuries to adjacent teeth, tissue emphysema, and aspiration, or ingestion of surgical instruments. This article addresses some surgical complications associated with dental implant placement and discusses how to avoid and manage them when they occur.
This study evaluated the soft tissue stability around 10 single-tooth implants. All cases were treated following the same protocol, which included guided bone regeneration and connective tissue grafting. One year after prosthesis insertion the soft tissue shrinkage on the buccal side of the implant crown was 0.6 mm on average. The soft tissue volume in the papilla area increased on average by 0.375 mm, and none of the papillae lost volume.
This study aimed to evaluate the impact of buccal bone defects and immediate placement on the aesthetic outcome of maxillary anterior single-tooth implants. The archives of the Department of Dental Implants & Tissue Regeneration, at «HYGEIA» Hospital, during a 5 years period (2010-2014), were retrospectively analyzed, in search of patients treated with a single-tooth implant after extraction of a maxillary incisor. The status of the buccal bone plate and the time of implant placement were recorded. The Pink Esthetic Score (PES) of each case was evaluated, with a maximum score of 14. In total, 91 patients were included in the study. The mean PES was 10.5. The outcome was considered satisfactory (PES ≥ 8) in 89% and (almost) perfect (PES ≥ 12) in 35% of the cases. Immediate implant placement had no impact on PES (p>0.05), even though it demonstrated slightly greater variability. On the other hand, buccal bone defects had a negative effect on PES (p<0.0001). As a conclusion, satisfactory aesthetic outcome can be achieved in single-tooth implants in the anterior maxilla. The presence of buccal bone defects is considered a negative prognostic factor, whereas immediate implant placement does not affect the aesthetic outcome.
Written by the foremost authority in the field, Dental Implants Prosthetics, 2nd Edition helps you advance your skills and understanding of implant prosthetics. Comprehensive coverage includes both simple and complicated clinical cases, with practical guidance on how to apply the latest research, diagnostic tools, treatment planning, implant designs, materials, and techniques to provide superior patient outcomes. © 2015 Mosby, Inc., an affiliate of Elsevier Inc. All rights reserved.
Since the introduction of the ad modum Branemark prototype prosthesis for the mandibular edentulous patient more than 30 years ago, design permutations have met clinician and patient considerations. Dental student training and specialist continuing education often rely on anecdotal reports of success to determine the recommended design for patients. Decision-making algorithms for treatment are optimally predicated on the best available evidence. The purpose of this article is to elucidate the benefit/risk calculus of various implant modalities for the mandibular edentulous patient.
Aim
To investigate whether the height and volume of the soft tissues and peri-implant bone levels around dental implants are stable, when soft tissue augmentation has been performed.
Materials and Methods
Three operators conducted a search on electronic databases (MEDLINE, COCHRANE, EMBASE) and a hand searching on the main journals dealing with periodontology and implantology until 30 October 2014. Only articles that considered peri-implant soft tissue augmentation performed in a group of at least 10 patients and with a follow-up of at least 1 year were selected. The outcome variables were peri-implant attached/keratinized tissue width (KTW) changes, peri-implant marginal soft tissue level (PSL) changes, and peri-implant marginal bone level (PBL) changes. The review was performed according to the PRISMA statements.
Results
Ten articles were selected for the qualitative synthesis, but only one meta-analysis was accomplished, indicating that 1 year after implant recession coverage procedures, a mean gain of 1.65 ± 0.01 mm (90% CrI [1.44; 1.85]) was observed.
Conclusions
There is no long-term evidence whether augmented soft tissues can be maintained over time and able to influence the peri-implant bone levels.
The purpose of this meta-analysis was to compare implant survival, marginal bone loss, and complications between immediate and conventional loading of single implants installed in the posterior mandible. An extensive electronic search was performed of PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials to identify relevant articles published up to January 2015. After the selection process, five studies met the eligibility criteria and were included. The results of the meta-analysis were expressed in terms of the odds ratio (OR) or standardized mean difference (SMD), with a confidence interval (CI) of 95%. Results were pooled according to heterogeneity using the fixed- or random-effects model. There was no statistically significant difference between the two techniques (immediate loading vs. conventional loading) with regard to implant survival (OR 1.71, 95% CI 0.40 to 7.36; P=0.47). There was no statistically significant difference in marginal bone loss (SMD -0.58, 95% CI -1.55 to 0.38; P=0.24). The reported mechanical and biological complications were common to both types of intervention, with the exception of probing depth, which was greater following the immediate loading technique (SMD 0.13, 95% CI -0.19 to 0.44), although this was not statistically significant (P=0.43).
Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
This work is intended for dentists/dental technicians who wish to achieve predictable results in fabricating implant-supported prostheses. Based on dental technology research followed by extensive clinical use, the book explains the methods and materials required for correctly-fitting frameworks.
Since the introduction of the endosseous concept to North America in 1982, there have been new permutations of the original ad modum Branemark design to meet the unique demands of treating the edentulous maxilla with an implant restoration. While there is a growing body of clinical evidence to assist the student, faculty, and private practitioner in the algorithms for design selection, confusion persists because of difficulty in assessing the external and internal validity of the relevant studies. The purpose of this article is to review clinician- and patient-mediated factors for implant restoration of the edentulous maxilla in light of the hierarchical level of available evidence, with the aim of elucidating the benefit/risk calculus of various treatment modalities.
Proper implant occlusion is essential for adequate oral function and the prevention of adverse consequences, such as implant overloading. Dental implants are thought to be more prone to occlusal overloading than natural teeth because of the loss of the periodontal ligament, which provides shock absorption and periodontal mechanoreceptors, which provide tactile sensitivity and proprioceptive motion feedback. Although many guidelines and theories on implant occlusion have been proposed, few have provided strong supportive evidence. Thus, we performed a narrative literature review to ascertain the influence of implant occlusion on the occurrence of complications of implant treatment and discuss the clinical considerations focused on the overloading factors at present. The search terms were ‘dental implant’, ‘dental implantation’, ‘dental occlusion’ and ‘dental prosthesis’. The inclusion criteria were literature published in English up to September 2013. Randomised controlled trials (RCTs), prospective cohort studies and case–control studies with at least 20 cases and 12 months follow-up interval were included. Based on the selected literature, this review explores factors related to the implant prosthesis (cantilever, crown/implant ratio, premature contact, occlusal scheme, implant–abutment connection, splinting implants and tooth–implant connection) and other considerations, such as the number, diameter, length and angulation of implants. Over 700 abstracts were reviewed, from which more than 30 manuscripts were included. We found insufficient evidence to establish firm clinical guidelines for implant occlusion. To discuss the ideal occlusion for implants, further well-designed RCTs are required in the future.
Approximately 2,700 patients are harmed by wrong-site surgery each year. The World Health Organization created the surgical safety checklist to reduce the incidence of wrong-site surgery. A project team conducted a narrative review of the literature to determine the effectiveness of the surgical safety checklist in correcting and preventing errors in the OR. Team members used Swiss cheese model of error by Reason to analyze the findings. Analysis of results indicated the effectiveness of the surgical checklist in reducing the incidence of wrong-site surgeries and other medical errors; however, checklists alone will not prevent all errors. Successful implementation requires perioperative stakeholders to understand the nature of errors, recognize the complex dynamic between systems and individuals, and create a just culture that encourages a shared vision of patient safety.
Purpose: The purpose of this retrospective analysis of expert opinions was to optimize the level of patient information prior to implant-prosthetic treatment. Materials and Methods: Twenty-eight expert opinion reports on implant treatment cases compiled between 1996 and August 2001 were analyzed. Results: Seventy-five percent of all cases subjected to expert opinion reports revealed generally inadequate patient information. Significant associations were found between diagnostic mistakes and a lack of or inadequate information about complications that occurred (P = .04). Inadequate prosthetic or periodontal pretreatment of the patient prior to implant treatment was associated with a lack of information concerning implant and periodontal maintenance (P = .023) as well as insufficient oral hygiene status (P = .001). Discussion: In addition to a general lack of patient information, a lack of information about possible complications and inadequate information about treatment risks, treatment costs, and treatment alternatives were also found. Conclusion: Optimization of pretreatment information for patients, as well as improvement of communication with patients throughout the whole treatment and maintenance period, seem to be necessary.
Despite the recent economic downturn, the dental implant market continues to grow year on year. Many more dentists are involved in the placement restoration of dental implants and dental implants are being placed in an extended range of clinical scenarios. Dental implant therapy remains a high risk area for the inexperienced in terms of civil negligence claims and General Dental Council hearings. Risk can be mitigated by:
• Ensuring appropriate indemnity
• Complying with the published requirements for training
• Maintaining detailed and extensive clinical records
• Completing the initial phases of history, examination and investigations robustly
• Recording a diagnosis
• Providing a bespoke written treatment plan that includes details of the need for treatment, the treatment options (the risks and benefits), the phases of treatment, the costs of treatment, the expected normal sequelae of surgery, the risks and complications of implant therapy and the requirement for future maintenance. The provision of treatment that is different in nature or extent to that agreed can result in a breach of contract as well as a claim for negligence
• Engaging sufficiently with the patient to obtain consent
• Providing written postoperative instructions detailing emergency arrangements, patients who are anxious or in pain may not retain oral information
• Making a frank disclosure of complication or collateral damage
• Considering referral at an early stage particularly if reparative surgery is required
The stress of complications or failure may impair a dentist's normally sound judgement; there may be financial pressure, or concerns regarding reputation. In some cases, dentists avoid making a frank disclosure, feel obliged to undertake complicated reparative surgery, fail to make a timely referral, fail to respond appropriately to patient's concerns and in some cases attempt to alter the clinical records.
However, in the best of hands and without negligence complications can and do occur. Complications that occur in the presence of good planning and communication and are managed appropriately do not amount to negligence, and are unlikely to lead to a successful claim.
PurposeThe aim of this study was to assess distortion inherent in casting, soldering, and simulated porcelain firings of screw-retained, implant-supported three-unit fixed partial dentures (FPDs).Materials and Methods
Ten wax patterns were fabricated on a die-stone cast containing two implants, 20 mm apart from center to center. Five specimens were cast in a high-palladium alloy, exposed to simulated porcelain firings, sectioned, and then soldered with low-fusing solder. Five specimens were cast, sectioned, soldered with high-fusing solder, and then exposed to simulated porcelain firings. For each specimen, two horizontal and six vertical distances between appropriately scribed reference points were measured with a traveling microscope. Comparisons were made among the various measurements taken after wax-pattern fabrication, casting, high- and low-fusing soldering, and each porcelain firing. Data were analyzed using a repeated-measures factorial ANOVA (α= 0.05).ResultsSignificant difference was detected in the amount of horizontal distortion during casting (53 ± 24 μm) and high-fusing soldering (−49 ± 50 μm), as well as in the amount of horizontal distortion during high-fusing soldering (−49 ± 50 μm) and low-fusing soldering (17 ± 26 μm). However, no clinically significant difference was found in the amount of horizontal distortion during casting, low-fusing, and high-fusing soldering. The greatest amount of distortion during the simulated porcelain firings took place during the oxidizing cycle.Conclusions
Soldering did not improve the casting misfit of a three-unit implant-retained FPD model. Metal-ceramic implant frameworks should be oxidized before intraoral fit evaluation.
Abstract The Nd:YAG and CO2 lasers have been shown to be bactericidal at relative low energy densities. However, at energy densities exceeding 120 J/cm2(CO2) and 200 J/cm2 (Nd:YAG). laser irradiation also causes irreparable root surface damage. The purpose of this study was to determine, in vitro, the energy density threshold at which microbial ablation could be achieved while inflicting the least amount of damage to the root surfaces of human teeth. Pairs of Escherkhia coli colonies cultured on broth agar were treated with a CO2 laser using a pulsed waveform at approximate energy densities ranging from 3 to 110 J/cm2. One of each colony-pair was then examined by scanning electron microscopy (SEM) and the other subcultured for viable microbes. Roots of extracted teeth were lightly scaled and treated by CO2 laser, again with pulsed beam using approximate energy densities of 3 to 110 J/cm2: and examined by SEM. Regardless of the level of energy density, residual bacteria could be subcultured from all laser treated microbial colonies. The inability of the laser to completely obliterate microbial colonies was likely due to: depth of energy penetration, difficulty in precisely overlapping beam focal spots, irregular beam profile, and presence of microbes at the periphery of the beam focal spot. The threshold energy density for bacterial obliteration was determined to be 11 J/cm2 and that for root damage was 41 J/cm2. Root damage was evident by charring, crater formation, meltdown and resolidification surface mineral, and increasing surface porosity. The results of this in vitro study indicate that when used at an energy density between 11 and 41 J/cm2: the CO2 laser may destroy microbial colonies without inflicting undue damage to the tooth root surface.
Inadequate dimensional stability caused by polymerization shrinkage has been reported concerning the various applications of acrylic resins. The objective of the study was to evaluate dimensional changes of two self-curing acrylic resins marketed as pattern and index material. Early volumetric changes were measured with a dilatometer and late linear changes were recorded with an inductive transducer. After 24 hours the volumetric shrinkage was 7.9% for Duralay resin and 6.5% for Palavit G resin; 80% of the change appears before 17 minutes at room temperature. Shrinkage was significantly increased when the proportion of powder in the mix was diminished. Results suggest that these resins should be used with some method to compensate for the shrinkage, when used as index material. However, the dimensional change might provide significant advantages for intracoronal castings.
Objectives:
The aim of this pilot study was to evaluate the efficiency, difficulty and operator's preference of a digital impression compared with a conventional impression for single implant restorations.
Materials and methods:
Thirty HSDM second year dental students performed conventional and digital implant impressions on a customized model presenting a single implant. The outcome of the impressions was evaluated under an acceptance criteria and the need for retake/rescan was decided. The efficiency of both impression techniques was evaluated by measuring the preparation, working, and retake/scan time (m/s) and the number of retakes/rescans. Participants' perception on the level of difficulty for the both impressions was assessed with a visual analogue scale (VAS) questionnaire. Multiple questionnaires were obtained to assess the participants' perception on preference, effectiveness and proficiency.
Results:
Mean total treatment time was of 24:42 m/s for conventional and 12:29 m/s for digital impressions (P < 0.001). Mean preparation time was of 4:42 m/s for conventional and 3:35 m/s for digital impressions (P < 0.001). Mean working time including retakes/rescans demanded 20:00 m/s for conventional vs. 8:54 m/s for digital impression (P < 0.001). On a 0-100 VAS scale, the participants scored a mean difficulty level of 43.12 (±18.46) for conventional impression technique and 30.63 (±17.57) for digital impression technique (P = 0.006). Sixty percent of the participants preferred the digital impression, 7% the conventional impression technique and 33% preferred either technique.
Conclusions:
Digital impressions resulted in a more efficient technique than conventional impressions. Longer preparation, working, and retake time were consumed to complete an acceptable conventional impression. Difficulty was lower for the digital impression compared with the conventional ones when performed by inexperienced second year dental students.
There are many similarities betwfeen flying commercial aircraft and surgery, particularly in relation to minimising risk, and managing potentially fatal or catastrophic complications, or both. Since 1979, the development of Crew Resource Management (CRM) has improved air safety significantly by reducing human factors that are responsible for error. Similar developments in the operating theatre have, to a certain extent, lagged behind aviation, and it is well recognised that we can learn much from the industry. An increasing number of publications on aviation factors relate to surgery but to our knowledge there is a lack of research in our own specialty. We discuss how aviation principles related to human factors can be translated to the operating theatre to improve teamwork and safety for patients. Clinical research is clearly needed to develop this fascinating area more fully.
The aim of this study was to review the literature on the restoration of single-tooth implants, and to develop evidence-based conclusions to optimize aesthetic, biologic and patient-related outcomes.
An electronic and hand search was conducted using the search terms 'dental implants, single-tooth; dental restoration, temporary; dental impression materials; dental impression technique; dental prosthesis, implant-supported; dental prosthesis design; dental abutments; dental occlusion; maintenance; survival; and survival analysis'. Resultant titles were screened, and full text was obtained where relevant. The authors selected the most appropriate articles, giving preference to systematic reviews and long-term, patient-based outcome data.
Thirty-nine articles were selected and critiqued by the authors.
There was strong suggestion by several authors that peri-implant soft tissue aesthetics can be sculpted through provisional restoration contour, but there are no clinical outcome studies to define or support this claim. Laboratory studies demonstrate that pick-up type impression copings in conjunction with elastomeric impressions are the most accurate means for transferring implant position to a dental cast. Laboratory and finite-element analysis studies suggest implants with an internal-type connection show improved stress distribution, but supportive clinical data are lacking. The authors of this review favour a screw-retained prosthesis for retrievability. Clinical and histological studies show that gold, titanium and zirconia ceramic abutment materials exhibit excellent biological responses, although there is insufficient data on the clinical service provided by zirconia as an implant-substructure material. The literature does not associate any particular occlusal scheme with superior clinical outcomes. Implant-borne single crowns offer comparable clinical service to tooth-borne fixed dental prostheses. However, single-tooth implant restorations are associated with an increased incidence of biological and technical complications.
The objective of this systematic review was to assess the influence of splinted and unsplinted oral implants in the mandibular and maxillary implant-supported overdenture therapy, concerning the implant survival, the peri-implant parameters, the prosthetic complications and the patient satisfaction. An electronic MEDLINE search complemented by manual searching was conducted to identify randomized clinical trials, prospective and retrospective cohort studies on implant-supported overdentures with a mean follow-up of at least 3 years. Twelve studies from an initial yield of 1022 titles were finally selected and data were extracted. After an observation period of more than 3 years, there was no difference in implant survival rates between splinted and unsplinted design. From most of the investigations included in this study, it was mentioned that the unsplinted design needs more prosthetic maintenance. In more of the studies that were dealing with the satisfaction of the patients wearing implant-supported overdentures, no significant difference in the preference of the patients was reported. No significant difference in the peri-implant outcome between splinted and unsplinted design was found. Within the limits of this systematic review, it is concluded that there was no significant difference between the two different designs of implant-supported overdentures with respect to the soft tissue health status or patient satisfaction, although the bar-supported overdentures have been shown to need less prosthetic maintenance.
Immediate-function implants have become an accepted alternative for fixed restoration protocols in edentulous mandibles on the basis of documented high success rates. The All-on-4 concept (Nobel Biocare, Göteborg, Sweden), a surgical and prosthetic protocol for immediate function involving the use of four implants to support a fixed prosthesis in patients with completely edentulous mandibles, represents one of these protocols. The authors conducted a study to document long-term follow-up of the All-on-4 concept.
This longitudinal study included 245 patients with a total of 980 immediate-function implants (four per patient), all placed in the anterior region, to support fixed full-arch mandibular prostheses. The inclusion criterion was having an edentulous mandible, or a mandible with hopeless teeth, in need of fixed implant restorations.
A total of 21 implants failed in 13 patients, giving cumulative patient-related and implant-related success rates of 94.8 percent and 98.1 percent, respectively, at five years, and 93.8 percent and 94.8 percent, respectively, with up to 10 years of follow-up. The prostheses' survival rate was 99.2 percent with up to 10 years of follow up.
The results support the conclusion that use of the All-on-4 immediate-function implant concept in completely edentulous mandibles is viable in the long term.
High prosthesis survival rates can be achieved by the use of four implants to support a full-arch fixed prosthesis in the mandible.
to evaluate the biological and technical complication rates of fixed dental prostheses (FDP) with end abutments or cantilever extensions on teeth (FDP-tt/cFDP-tt) on implants (FDP-ii/cFDP-ii) and tooth-implant-supported (FDP-ti/cFDP-ti) in patients treated for chronic periodontitis.
from a cohort of 392 patients treated between 1978 and 2002 by graduate students, 199 were re-examined in 2005. Of these, 84 patients had received ceramo-metal FDPs (six groups).
at the re-evaluation, the mean age of the patients was 62 years (36.2-83.4). One hundred and seventy-five FDPs were seated (82 FDP-tt, 9 FDP-ii, 20 FDP-ti, 39 cFDP-tt, 15 cFDP-ii, 10 cFDP-ti). The mean observation time was 11.3 years; 21 FDPs were lost, and 46 technical and 50 biological complications occurred. Chances for the survival of the three groups of FDPs with end abutments were very high (risk for failure 2.8%, 0%, 5.6%). The probability to remain without complications and/or failure was 70.3%, 88.9% and 74.7% in FDPs with end abutments, but 49.8-25% only in FDPs with extensions at 10 years.
in patients treated for chronic periodontitis and provided with ceramo-metal FDPs, high survival rates, especially for FDPs with end abutments, can be expected. The incidence rates of any negative events were increased drastically in the three groups with extension cFDPs (tt, ii, ti). Strategic decisions in the choice of a particular FDP design and the choice of teeth/implants as abutments appear to influence the risks for complications to be expected with fixed reconstruction. If possible, extensions on tooth abutments should be avoided or used only after a cautious clinical evaluation of all options.
The debate between screw- versus cement-retained implant prostheses has long been discussed but the best type of implant prosthesis remains controversial among practitioners. An understanding of their properties will help the clinician in selecting the ideal prosthesis for each clinical case while promoting final esthetic outcomes. With the evolving technology and knowledge, an update of the current trends is necessary. This article provides an overview of the different characteristics of screw- and cement-retained implant restorations, and how they may influence the esthetics, retrievability, retention, passivity, occlusion, accessibility, cost, and provisional restorations. Problems and complications frequently encountered are discussed and treatment solutions are proposed.
The purpose of this study was to evaluate the responses of peri-implant tissue in the presence of keratinized mucosa.
A total of 276 implants were placed in 100 patients. From the time of implant placement, the average follow-up observation period was 13 months. The width of keratinized mucosa was compared and evaluated through the gingival inflammation index (GI), plaque index (PI), the pocket depth, mucosal recession, and marginal bone resorption.
The GI, PI, and pocket depth in the presence or absence of the keratinized gingiva did not show statistically significant differences. However, mucosal recession and marginal bone resorption experienced statistically significant increases in the group of deficient keratinized mucosa. Based on implant surface treatments, the width of keratinized gingiva and crestal bone loss did not show a significant difference.
In cases with insufficient keratinized gingiva in the vicinity of implants, the insufficiency does not necessarily mediate adverse effects on the hygiene management and soft tissue health condition. Nonetheless, the risk of the increase of gingival recession and the crestal bone loss is present. Therefore, it is thought that from the aspect of long-term maintenance and management, as well as for the area requiring esthetics, the presence of an appropriate amount of keratinized gingiva is required.
A survey of the characteristics of an open smile was conducted with 454 full-face photographs of randomly selected dental and dental hygiene students. Findings show that an average smile exhibits approximately the full length of the maxillary anterior teeth, has the incisal curve of the teeth parallel to the inner curvature of the lower lip, has the incisal curve of the maxillary anterior teeth touching slightly or missing slightly the lower lip, and displays the six upper anterior teeth and premolars. Consideration of the characteristics may be useful in improving the esthetics of restorations.
In a previous study on 42 young adult, periodontally healthy subjects without any attrition, abrasion or crown restoration, gingival thickness (GTH) was determined at facial aspects of premolars, canines and incisors by a novel ultrasonic device. GTH strongly depended on periodontal probing depth, width of gingiva (WG), and tooth type. Whereas the ratio of crown width to its length (CW/CL) was not identified as an explanatory variable, a significant influence of the subject was ascertained. The aim of the present study was to extend these analyses in order to identify subjects with different morphological characteristics of gingiva, i.e., gingival phenotypes. When employing cluster analysis on standardized parameters mean GTH, WG and CW/CL of upper canines, lateral and central incisors, 3 clusters were identified. Cluster A comprised 2/3 of subjects, displaying "normal" GTH, WG and CW/CL. Cluster B (n = 9, 21%) had a significantly thicker and wider gingiva, and a more quadratic form of upper front teeth. A 3rd cluster (cluster C, n = 5, 12%) was identified showing "normal" GTH, high CW/CL, but a narrow zone of keratinized tissue. Some characteristics of gingival phenotype of the upper front tooth region were also found at upper premolars (WG, CW/CL) but in general not at mandibular teeth. Present results clearly indicate evidence for the existence of different gingival phenotypes. Clinical relevance of these observations has to be tested in longitudinal studies.
The process of removing excess cement from subgingival margins after cementation of restorations to implant abutments may lead to scratching of the abutments or incomplete cement removal.
The purpose of this study was to investigate and to compare the surfaces of abutments after the removal of three cements (glass ionomer, resin, and zinc phosphate) by use of three instruments (gold coated scaler, rigid plastic scaler, and stainless steel explorer).
Six investigators removed zinc phosphate, glass ionomer, and resin cements with explorers, gold coated scalers, and rigid plastic scalers with a model simulating clinical conditions. The surface of Brånemark abutments with cemented restorations were examined with a microscope at 20x for scratches and cement remnants.
Statistical analysis of the results were inconclusive about which combination of instrument and cement worked most effectively.
A surprising amount of cement remnants and scratching of abutments was observed. Although the six investigators were experienced in prosthodontic and implant procedures, there was variation in the results of their cement removal.
This in vitro study quantified the marginal discrepancy of the implant-to-prosthetic-crown interface on nonsubmerged dental implants restored with either a cemented or a screw-retained approach. Metal-ceramic crowns were fabricated for 20 ITI 4.1 x 10 mm solid-screw titanium implants. Ten implants received octa abutments and screw-retained crowns fabricated on premachined gold cylinders. The remaining 10 implants were restored with 5.5-mm solid abutments and metal-ceramic crowns cemented alternately with a glass-ionomer or a zinc phosphate luting agent. Inspection of the implant-crown interface was conducted using light microscopy under x 50 magnification at selected stages in the process of crown fabrication. Statistical analysis revealed a significant difference (P < .001) in the mean marginal fit between screw-retained (8.5 +/- 5.7 microns) and luted implant-supported crowns. This difference was observed both before (54.4 +/- 18.1 microns) and after cementation with glass-ionomer (57.4 +/- 20.2 microns) or zinc phosphate (67.4 +/- 15.9 microns).
Two approaches to the problem of human fallibility exist: the person and the system approaches. The person approach focuses on the errors of individuals, blaming them for forgetfulness, inattention, or moral weakness. The system approach concentrates on the conditions under which individuals work and tries to build defences to avert errors or mitigate their effects. High reliability organisations - which have less than their fair share of accidents - recognise that human variability is a force to harness in averting errors, but they work hard to focus that variability and are constantly preoccupied with the possibility of failure.
The aim of this study was to assess distortion inherent in casting, soldering, and simulated porcelain firings of screw-retained, implant-supported three-unit fixed partial dentures (FPDs).
Ten wax patterns were fabricated on a die-stone cast containing two implants, 20 mm apart from center to center. Five specimens were cast in a high-palladium alloy, exposed to simulated porcelain firings, sectioned, and then soldered with low-fusing solder. Five specimens were cast, sectioned, soldered with high-fusing solder, and then exposed to simulated porcelain firings. For each specimen, two horizontal and six vertical distances between appropriately scribed reference points were measured with a traveling microscope. Comparisons were made among the various measurements taken after wax-pattern fabrication, casting, high- and low-fusing soldering, and each porcelain firing. Data were analyzed using a repeated-measures factorial ANOVA (alpha = 0.05).
Significant difference was detected in the amount of horizontal distortion during casting (53 +/- 24 microns) and high-fusing soldering (-49 +/- 50 microns), as well as in the amount of horizontal distortion during high-fusing soldering (-49 +/- 50 microns) and low-fusing soldering (17 +/- 26 microns). However, no clinically significant difference was found in the amount of horizontal distortion during casting, low-fusing, and high-fusing soldering. The greatest amount of distortion during the simulated porcelain firings took place during the oxidizing cycle.
Soldering did not improve the casting misfit of a three-unit implant-retained FPD model. Metal-ceramic implant frameworks should be oxidized before intraoral fit evaluation.
The regeneration of gingival papillae after single-implant treatment is an area of current investigation. This study was designed to determine: 1) whether the distance from the base of the contact point to the crest of the bone would correlate with the presence or absence of interproximal papillae adjacent to single-tooth implants, and 2) whether the surgical technique at uncovering influences the outcome.
A clinical and radiographic retrospective evaluation of the papilla level around single dental implants and their adjacent teeth was performed in the anterior maxilla in 26 patients restored with 27 implants. Six months after insertion, 17 implants were uncovered with a standard technique, while 10 implants were uncovered with a technique designed to generate papilla-like formation around dental implants. Fifty-two papillae were available for clinical and radiographic evaluation. The presence or absence of papillae was determined, and the effects of the following variables were analyzed: the influence of the 2 surgical techniques; the vertical relation between the papilla height and the crest of bone between the implant and adjacent teeth; the vertical relation between the papilla level and the contact point between the crowns of the teeth and the implant; and the distance from the contact point to the crest of bone.
When the measurement from the contact point to the crest of bone was 5 mm or less, the papilla was present almost 100% of the time. When the distance was > or = 6 mm, the papilla was present 50% of the time or less. The mean distance between the crest of bone and the most coronal papilla level (interproximal soft tissue height) was 3.85 mm (SD = 1.04). When comparing the conventional and modified surgical technique, the relation shifted from 3.77 mm (SD = 1.01) to 4.01 mm (SD = 1.10), respectively.
These results clearly show the influence of the bone crest on the presence or absence of papillae between implants and adjacent teeth. The data also show a positive influence for the modified surgical technique, aimed at reconstructing papillae at the implant uncovering.