The aim of this study was to compare the survival of implants placed in mature bone with the survival of implants placed in fresh extraction sockets in the same patients.
A retrospective study of patients treated simultaneously with at least one immediate and one nonimmediate implant was carried out for the period 2005 to 2008. Data were recorded for patient age and sex; implant length, diameter, and position; and, for postextraction implants, distance between the implant and the alveolar bone.
One thousand twenty-two implants were placed in 150 patients; 480 were placed immediately and 542 were placed in mature bone. The mean implant survival rate was 93.4%; survival rates were 93.8% for immediate implants and 93.2% for nonimmediate implants. The failure rate in the maxilla was 5.2% and in the mandible it was 2.8%. The failure rate for immediate implants in the posterior maxilla was 8.5%, which was statistically significantly higher than for implants placed elsewhere. Of the failed implants, 72% were early failures.
The survival rate of implants placed in fresh extraction sockets was similar to that of implants placed in mature bone. A statistically significantly higher failure rate was seen with immediate implants placed in the posterior maxilla.
The aim of this multicenter study was to evaluate cumulative success and survival rates of ITI implants after 7 years. A complete medical report was obtained for all 440 patients enrolled in this investigation, which involved 10 different private practices. The 1,022 consecutively placed implants were distributed between completely edentulous, partially edentulous, and single-tooth replacement cases. During the annual follow-up visit, each implant was examined both clinically and radiographically using predefined success criteria. The cumulative survival and success rates were calculated for all implants. Implant subgroups were defined according to the medical history of the patients or pooled according to various indications, locations, implant designs, or implant lengths. In each subgroup, the related cumulative success rate was statistically compared to the global cumulative success rate. Fifteen implants (1.4%) were regarded as early failures, and at the end of the follow-up, the global failure rate reached 6.6%; 30 implants (3%) were lost to follow-up. At 5 years, the cumulative survival rate was 95.4%; this declined to 92.2% at 7 years. The weakest success rates were observed for implants placed in older patients, periodontally treated patients, and completely edentulous arches. Conversely, cumulative success rates that were significantly above average were observed for patients between 40 and 60 years old without pathology, implants placed after bone regeneration, solid-screw implants, implants placed in edentulous spaces, and implants placed as single-tooth replacements. This investigation has demonstrated that in these 10 private practice settings, the success rate for ITI implants remained high for up to 5 years and declined slightly between 5 and 7 years. It should be noted that in later year intervals, a relatively small number of implants remained for the analysis of cumulative success rates.
To evaluate the retention of bone around implants placed immediately following tooth extraction and used to support dental prostheses.
Materials and methods:
Patients from a previous study of implants placed immediately following tooth extraction were recalled to the original practice to obtain dental radiographs, which were then used to compare bone levels after 1 to 22 years of clinical function supporting dental prostheses. All radiographs were evaluated by measuring the bone within the implant threads. Implant bone maintenance was correlated with smoking history, type of implant surface, antibiotics used in conjunction with surgery, bisphosphonate use, presence of splinted restorations, anatomical location (mandible or maxilla and anterior or posterior), sex, and past periodontal disease status. Statistical analysis was performed using the Mann-Whitney test for statistical significance of differences in mean bone loss.
A total of 1,187 implants were identified, with mean bone loss of 0.52 ± 0.79 mm. Overall bone loss was less than 1.5 mm in 90% of the implants studied. Bone loss was greater in women (0.61 ± 0.91 mm vs 0.44 ± 0.69 mm in men; P = .002). There was a correlation between bone loss and patient age at the time of tooth loss, with patients below the age of 50 experiencing significantly more loss (mean loss, 0.76 ± 1.07 mm at age < 50 and 0.46 ± 0.71 mm at age > 50; P = .008). Other significant differences were seen with implant surface (machined surface, 0.57 ± 0.77 mm; roughened surface, 0.44 ± 0.84 mm; P = .0049), maxilla vs mandible in molar areas (maxilla, 0.68 ± 0.83 mm; mandible, 0.43 ± 0.80 mm; P = .0001), and platform width (regular, 0.46 ± 0.77; wide, 0.83 ± 0.94 mm; P ≤ .0001). None of the other factors demonstrated significant differences.
Bone loss of 1.5 mm or less was observed in 90% of the patients followed. Bone loss was correlated with age, sex, implant surface, anatomical location, and platform width. There was no statistical correlation between bone loss and any other factors evaluated.
The purpose of this study was to identify retrospectively the predictors of implant survival when the flapless protocol was used in two private dental practices.
Materials and methods:
The collected data were initially computer searched to identify the patients; later, a hand search of patient records was carried out to identify all flapless implants consecutively inserted over the last 10 years. The demographic information gathered on statistical predictors included age, sex, periodontal and peri-implantitis status, smoking, details of implants inserted, implant locations, placement time after extraction, use of simultaneous guided hard and soft tissue regeneration procedures, loading protocols, type of prosthesis, and treatment outcomes (implant survival and complications). Excluded were any implants that required flaps or simultaneous guided hard and soft tissue regeneration procedures, and implants narrower than 3.25 mm.
A total of 1,241 implants had been placed in 472 patients. Life table analysis indicated cumulative 5-year and 10-year implant survival rates of 97.9% and 96.5%, respectively. Most of the failed implants occurred in the posterior maxilla (54%) in type 4 bone (74.0%), and 55.0% of failed implants had been placed in smokers.
Flapless dental implant surgery can yield an implant survival rate comparable to that reported in other studies using traditional flap techniques.
The purpose of this prospective multicenter study was to evaluate the efficacy of 3i threaded implants for the treatment of edentulous patients in a 1- to 5-year period. This article reports the total data and global results of 3 threaded designs of 3i implants: self-tapping, ICE, and Osseotite.
A total of 1,583 implants (619 ICE, 545 Osseotite, and 419 self-tapping) were placed between 1995 and 1999 in 528 patients at 13 European clinical centers. The average age of the patients was 53.6 years. Clinical and radiographic evaluations were performed annually for up to 5 years.
Of the total implants, 707 were placed in the maxilla and 876 in the mandible. A total of 1,162 implants were placed in posterior segments. Forty-eight implants were lost to follow-up and 55 were failures. The most frequent prosthetic indication was the short-span fixed prosthesis (440 cases), followed by 172 single-tooth replacements, 56 long-span prostheses, and 4 overdentures. Radiographic evaluation after 6, 12, and 24 months of implant loading showed, respectively, mean crestal bone loss of 0.04 +/- 1.3 mm, 0.12 +/- 1.6 mm, and 0.2 +/- 1.7 mm. A cumulative survival rate of 96.5% was observed 5 years after implant placement, with 97.2% survival in the maxilla and 95.8% in the mandible. The survival rate was similar in anterior (96.7%) and posterior (96.5%) segments.
A total of 55 failures were reported in this study with 47 early failures and 8 late failures. The rate of late failures is of utmost importance for the restorative dentist.
This clinical study gives evidence of very high success rates using 3 threaded designs of 3i implants.
A total of 1,920 IMZ implants, placed between March 1984 and December 1993, were evaluated retrospectively. The Kaplan-Meier cumulative survival rate of the implants was 89.9% after 60 months and 83.2% after 100 months. Life table analysis revealed a statistically significantly lower cumulative survival rate for maxillary implants (71.6% at 60 months and 37.9% at 100 months) than for mandibular implants (90.4% at 100 months). Implants placed in the anterior region of the maxilla failed significantly more often than those placed in the posterior region. This was not observed in the mandible. The age and sex of the patients, the status of the jaw (edentulous, partially edentulous), the time of implant placement in relation to tooth extraction, and the length and diameter of the implants had no statistically significant influence on the cumulative survival rate.
In a retrospective study, Kaplan-Meier implant survival analyses were conducted on 883 patients with 1,964 implants of various systems placed, followed up, documented, and statistically evaluated at an oral surgery and dentistry practice between January 1981 and January 1997. The goal of this study was to evaluate the success of osseointegrated implants of the Brånemark, Frialit-1 (Tübinger Implant), Frialit-2, and IMZ systems and Linkow blade implants. For all systems, mandibular implants were generally more successful than maxillary implants. The preprosthetic loss rate was 1.9%, and 4.3% of implants were lost after prosthetic treatment. The lowest loss rates were seen with implants in intermediate and distal extension spaces and with single-tooth replacements using IMZ, Frialit-2, and Brånemark implants. In edentulous arches, implants of the IMZ and Brånemark systems had the lowest failure rates.
Closure of a 1.5-cm oral antral fistula was done in combination with sinus floor and extraction socket grafting using recombinant human bone morphogenetic protein-2 within a collagen sponge matrix. The approach to the sinus was transalveolar, with elevation of the sinus membrane done through a molar extraction socket. Following graft placement, soft tissue repair was done with a buccal advancement flap. A dental implant was subsequently placed and restored. Peri-implant bone and implant stability were well maintained at the 1-year follow up examination.
The aim of this study was to analyze the survival rate of endosseous implants placed in the partially dentate maxilla treated with sinus inlay block bone grafts.
Seventeen patients were subjected to bone augmentation procedures prior to or in conjunction with implant placement. Bone volumes were regarded as insufficient for implant treatment unless a bone grafting procedure was performed. The patients were treated with sinus inlay block bone grafts and endosseous implants in a 1- or 2-stage procedure. A total of 69 implants were placed in the patients who were followed for 29 to 101 months (mean, 53.1 months). The retrospective patient group was also prospectively followed using a standardized clinical and radiographic study design.
The implant survival rate was 91.3% (63/69). All implants were lost during the period from abutment connection to connection of the definitive prosthesis. All bone grafts were stable. Bone grafts supported 48 implants, of which 5 failed (10.4%). In the residual bone, 21 implants were placed, of which 1 failed (4.8%). All patients received a fixed partial prosthesis, which was stable during the follow-up period.
The results of this investigation revealed a satisfactory clinical outcome of implant placement in grafted partially dentate maxillae after a mean follow-up of 53.1 months.
The purpose of this study was to evaluate indications, surgical problems, complications, and treatment outcomes related to the placement of zygomatic implants. A second aim was to determine any prosthetic difficulties and complications.
Twenty-five zygomatic implants were placed in 13 patients between April 1999 and December 2001. The patient age range was between 49 and 73 years, with a mean age of 59 years. All patients showed severe resorption of alveolar bone in the maxilla. All but 2 patients were smokers. Two patients had a history of cleft palate surgery, and 2 patients were known to be bruxers. Standard recommended surgical protocol was followed, and treatment was performed under general anesthesia. After abutment surgery, 9 patients received bar-retained overdentures, and 4 patients received fixed prostheses.
No implants were lost, and few surgical complications were experienced. The follow-up period was 11 to 49 months.
Although surgical problems precipitated by difficult anatomy in cleft patients and a patient with reduced interarch access were experienced, the results were favorable. Fabricating a functional and esthetic prosthesis can be a challenge.
Zygomatic implants provide a treatment option for patients with severe maxillary resorption, defects, or situations where previous implant treatment has failed. In this experience, treatment with zygomatic implants was a predictable method with few complications, even in a group of patients that would not be considered ideal for implant treatment.
This clinical study using a specific technique was carried out to determine the clinical effectiveness of zygomatic implants under an immediate loading protocol.
All patients treated between May 2000 and October 2006 who received zygomatic implants were included in this retrospective analysis. All patients were treated using the same surgical and restorative protocol. The following data were recorded: gender, age, type of implant, number of implants placed, dimensions of implants, and implant and prosthesis survival.
Fifty-six consecutive patients (29 women, 27 men; mean age of 60.58 years [range, 38.78 to 84.01]) were treated. All were in need of oral reconstruction and had maxillary atrophy that warranted zygomatic implant placement. One hundred ten zygomatic implants were placed in these 56 patients. Four of the 110 zygomatic implants failed, resulting in a cumulative survival rate of 96.37% with follow-up data no less than 9 months and in excess of 5 years. All four failures were turned-surface zygomatic implants. There have been no failures to date with the titanium anodized-surface zygomatic implants. The prosthesis survival rate was 100.0%.
In this retrospective analysis of 56 patients receiving 110 zygomatic implants, the survival rate of zygomatic implants was in excess of 96% over a period of 9 months to 5 years. This technique resulted in a stable and predictable prosthetic reconstruction.
A technique is presented which utilizes a trephine with a 3.0-mm external diameter followed by an osteotome to implode a core of maxillary posterior alveolar bone prior to immediate implant placement.
The technique and its indications and contraindications are described in detail.
One hundred sixteen implants were placed and uncovered utilizing this technique. Two implants were mobile at the time of uncovering.
One hundred fourteen implants were restored and have been functioning successfully for up to 4 years according to the Albrektsson criteria, yielding a success rate of 98.3%.
No implants have been lost or are failing in function.
Controversy over the long-term clinical effectiveness of hydroxyapatite (HA)-coated dental implants still persists, despite numerous clinical studies documenting high survival rates. The Ohio State University College of Dentistry undertook a 5-year prospective study of 429 HA-coated cylindric implants placed into 121 patients to determine the long-term clinical performance of the implants.
All study subjects were patients screened and evaluated in the university's dental clinic by one of the principal investigators and one member of the surgical team. A total of 429 HA-coated implants were placed in 121 patients. The Ohio State University Human Subjects Committee approved and reviewed this study.
At the time of this report, 375 implants had completed 5 years of clinical follow-up. Beyond the 5-year limit of the study, 282 implants had completed 6 years and 114 implants had completed 7 years of clinical monitoring. The cumulative survival rate was 96% at 5 years and 95% at 7 years of follow-up. Mean combined mesial/distal bone loss was 1.2 mm in the mandible and 1.4 mm in the maxilla after 5 years of functional loading. Implant failures were most commonly associated with short implants or angled abutments.
Prospective clinical data are extremely valuable for clinicians evaluating the reliability of dental implant systems. In the present study, the implants achieved 100% osseointegration with minimal marginal bone loss, and 96% of the implants remained in function at 5 years.
The HA-coated cylindric implants in this study provided a predictable means of oral rehabilitation.
In anterior maxillary extraction sockets, immediate implants are usually positioned along the palatal slope of the extraction socket. However, this positioning frequently causes unintentional slipping of dental implant toward thin labial plate, leading to its fracture or perforation. To prevent this, the present authors have created a simple apico-palatal guiding slot in the extraction socket following atraumatic extraction. Guided by this slot, sequential drilling up to implant placement can be easily accomplished while maintaining ideal axial orientation of the dental implant.
The purpose of this study was to compare marginal bone loss and success rates 1 year after implants had been placed in maxillary molar sites, either immediately postextraction or after the extraction sites had healed (delayed).
A retrospective case study was made of subjects treated with immediate or delayed dental implants in the maxillary molar region between January 2006 and December 2008. A protocol was prepared in which patient age, sex, implant length and diameter, type of prosthesis, buccal plate width, and use of bone grafting were recorded. After 12 months, data relating to the clinical and radiologic conditions of the implants and the success rate according to the criteria of Buser et al were recorded. The variables were analyzed statistically (Student t test, Pearson correlation, Games-Howell test).
The study included 123 implants placed in 70 patients; 35 implants were immediate and 88 were delayed. Two immediate and six delayed implants failed, resulting in success rates of 94.3% and 93.2%, respectively. Average marginal bone loss was 0.56 mm for immediate implants and 0.67 mm for delayed implants.
The placement of immediate implants in maxillary molar sites achieved similar results to implants placed in healed sites in the same region after 12 months. No statistically significant differences were found between implant survival rates or average marginal bone loss.
The purpose of this study was to analyze retrospectively the survival rate of implants used in pairs to support a single molar crown over a long-term follow-up period and to compare the efficacy of this technique to other existing methods of treatment.
The charts and radiographs of 105 patients who each received two implants to support a screw-retained single molar were examined according to the following criteria: age, gender, location of implant, time of loading (delayed versus immediate), opposing dentition, and the existence of adjacent implants.
Patients with follow-up between 3 and 12 years were selected to illustrate the long-term outcomes of the two-implant replacement procedure. Two hundred fifty implants were placed in 125 molar sites in 105 patients. Five of the 250 implants failed, resulting in a cumulative survival rate of 98.0%. Seven of 125 restorations experienced porcelain fracture (5.6%), seven prosthetic screws loosened (5.6%), and one abutment screw loosened (< 1.0%). Discussion: The placement of two implants to support a screw-retained single molar successfully reduces rotational forces that create stress on the implant. A single regular-diameter or even a wide-diameter implant is susceptible to these forces, which may lead to fatigue over the long term.
Two implants for the replacement of a single molar represent an effective method that provides a high survival rate over a long-term follow-up period. This approach produced a cumulative survival rate higher than that usually seen in studies of single implants used for molar replacement. The two implant-supported molar crown showed fewer complications than single implant-supported molar crowns.
This prospective clinical study evaluated the performance of 290 tapered, anodic oxidized (TiUnite) titanium implants placed in compromised bone in a consecutive series of 126 patients.
Inclusion criteria were: (1) a need for dental implants in either a single-tooth or partially edentulous segment, (2) sufficient medical fitness to undergo the procedure, (3) enough bone to enable placement of a 10-mm or longer implant, and (4) compromised bone, as judged by computerized tomography and confirmed by clinical findings, in at least one implant site. Implants were placed and left unloaded for at least 6 months (mean 9.9 +/- 3.9 months) before placement of the first provisional prosthesis and followed for at least 3 years after loading. Marginal bone was measured by an independent radiologist.
A second-stage uncovering was required for approximately half the implants. Failure of osseointegration was observed for only two implants; all other implants provided the intended prosthetic support during the entire observation period. The overall implant survival rate after 3 years of loading was 99.3%. The average mean changes in the marginal bone level showed stability (-2.70 mm, -2.67 mm, and -2.74 mm at 1, 2, and 3 years postloading, respectively).
Using a modified surgical technique that minimized the osteotomy dimensions, tapered implants with an oxidized surface proved to be a predictable support for fixed prostheses in both grafted and ungrafted compromised bone. Marginal bone levels were stable throughout at least 3 years of follow-up.
Ninety-six partially edentulous maxillae and mandibles were consecutively treated with 127 freestanding fixed prostheses supported by 354 implants. The patients were followed for 1 year and the overall success rate was 98.6% for the examined implants. None of the inserted prostheses was lost during the observation period. The most commonly reported problems during the first year of function were related to loose gold screws and esthetic complaints, complications that were easily resolved. Furthermore, the total number of complications was low and was less than has been reported for routine full-arch fixed prostheses.
The aim of the present retrospective clinical study was to compare the efficacy of two piezoelectric cutting inserts for the incidence, size, and types of sinus membrane perforations, and to evaluate their various advantages for lateral window osteotomy.
The study consisted of 127 maxillary sinus augmentation procedures performed at two centers. A bony window was made on the lateral wall of the maxillary sinus with either the piezoelectric saw or the round diamond insert and repositioned over the bone graft as a homologous bony barrier. The rate of membrane perforation during sinus augmentation between the two groups was compared and analyzed statistically by the chi-square test and the two-sample t test.
Seven perforations were seen in the 127 maxillary sinus procedures in this study (5.51%). Six perforations in 84 cases (7.14%) occurred with the piezoelectric saw and one perforation in 43 sites (2.32%) occurred while using the round insert. No statistically significant difference was found between the rates of membrane perforation between the two inserts.
The lateral bony window was created effectively with either of the two kinds of piezoelectric inserts. The membrane perforation rate was not significantly affected by the type of piezoelectric insert. The piezoelectric saw insert was more advantageous than the round diamond due to its greater precision and easier repositioning of the lateral bony window as a barrier.
The aim of this retrospective study was to evaluate the long-term survival rates and the frequency of complications associated with single implants and their associated restorations.
Materials and methods:
A retrospective cohort study was performed in patients who received dental implants between 1997 and 2007. The cohort included patients who had a single implant restored with a cemented or screwed restoration that had been in function for more than 2 years. The cumulative implant survival rates and peri-implant conditions (marginal bone loss, pocket depth, and plaque, gingival, and bleeding indices), as well as prosthodontic maintenance requirements, were evaluated. Descriptive statistics, the chi-square test, and regression models were used.
Seventy-three implants were placed in 44 patients (32 women, 12 men; mean age, 48 years). All implants were available for follow-up after 2 to 13 years (mean follow-up, 60 months). The overall cumulative 5-year survival rates for implants were 95.9%, and most of the prostheses (98.6%) remained functional throughout the observation period. The overall frequency of complications was 29.6% (4.3% inflammatory, 22.5% prosthetic, 2.8% operative). The average peri-implant marginal bone loss was 1.8 mm. Peri-implant soft tissue conditions such as plaque and bleeding indices and pocket depths were also satisfactory. However, the presence of inflammation was significantly associated with pocket depth and gingival keratinized mucosa. The need to retighten loose abutment screws (21%) was the most frequent prosthodontic maintenance performed. However, all loose abutment screws occurred in prostheses retained with titanium screws, and 92.9% of the prostheses had a UCLA-type abutment.
The implants and the associated prosthetic constructions used in this study showed excellent survival rates. However, there was a high frequency of prosthetic complications associated with titanium screws and UCLA cast abutments. Other prosthetic components may have yielded different results.
This human study sought to compare, from an immunohistochemical point of view, matrix metalloproteinases (MMPs) 2, 3, 8, 9, and 13 in the soft tissues around titanium and zirconium oxide healing caps.
Materials and methods:
Five patients participated in this study. All patients received 3.8 × 11-mm dental implants, which were left to heal in a nonsubmerged (single-stage) mode. Healing caps (3.8 mm in diameter and 3.0 mm in height) were inserted in all implants. Half of the implants were randomly supplied with standard, prefabricated caps of commercially pure titanium (control), while the other half were randomly provided with zirconium oxide caps (test). After a 6-month healing period, gingival biopsy specimens were obtained with a circular scalpel around the healing caps of both groups, without unscrewing or removing the healing caps, and the samples underwent immunohistochemical processing for MMPs 2, 3, 8, 9, and 13.
Statistically significant differences were found in the values of MMP-8 in the cells of the inflammatory infiltrate, with higher values for the titanium samples. Statistically significantly higher values were found, also in the titanium samples, for MMP-9 in the endothelial cells of the blood vessels. No statistically significant differences were found for any other MMPs.
The present results showed that the soft tissues around titanium healing caps underwent a higher rate of restorative processes, most probably correlated to the MMP levels observed in the tissues.
Thirteen commercially available oral implant systems were investigated with respect to design and surface topography. The implants were divided into four groups, depending on their different surface materials and treatments. Surface topography was measured with a measurement system for noncontact surface profilometry using confocal scanning microscopy. Results indicated that design, as well as surface topography, varied considerably between the different implant systems.
Between February 1995 and May 1996, 71 patients received treatment that involved 1 or more wide Screw-Vent implants. A total of 131 wide implants were placed. All patients were recalled 1 year after loading. Seven patients (14 implants) were lost to follow-up. Six implants were removed before completion of prosthetic treatment. One hundred eleven implants were evaluated at the recall examination. Almost all implants (109) supported a fixed prosthesis; in the majority of patients (93 implants), it was a fixed partial prosthesis. The mean loading time was 17 months (range, 11 to 21 months). No implants were lost during the loading period. The overall survival rate was 95%. The survival rate for mandibular implants was 94%; for maxillary implants, it was 96%. These percentages were not statistically different. Crestal bone remodeling was examined using periapical radiographs. After 17 months in function, only 3 implants (2.5%) presented bone loss beyond the first thread.
The aim of this study was to assess the long-term reliability of Locator-retained mandibular or maxillary overdentures and to examine clinical and radiographic parameters of the supporting implants.
Materials and methods:
The authors performed a retrospective analysis of a case series. After implant placement and a submerged healing phase of about 3 months, all implants were restored with Locator-retained overdentures. The follow-up examinations included the assessment of the Plaque Index (PI) and sulcus Bleeding Index (SBI) as well as peri-implant soft tissue parameters, such as bleeding on probing (BOP) and pocket probing depth (PPD). The mean marginal bone loss was measured on panoramic radiographs. The clinical performance of Locator components and the prosthetic restoration were evaluated. Descriptive statistics were computed. For statistical analysis, non-parametric and parametric tests with respect to the variable scale were used. The significance level was set as P ≤ .05.
The sample was composed of 33 patients (18 men, 15 women) with a mean age of 66.8 years who received 132 implants (84 in the anterior maxilla, 48 in the anterior mandible). After 32.9 months of follow-up, one maxillary implant was lost. All prosthetic restorations were still functionally in place at the last follow-up appointment with moderate prosthodontic maintenance effort. Clinical parameters and radiographs revealed healthy tissues around most implants.
Within the limitations of this study, it can be concluded that Locators are a predictable alternative for anchorage of mandibular and maxillary overdentures with good clinical performance of both the prosthetic restorations and the supporting implants.
Guided bone regenerative therapy has become a significant component of clinical implant practice. Initial reports have demonstrated success rates of implants in regenerated bone under function comparable to the success rates of implants placed in native nonregenerated host bone. This report documents the success and failure rates of osseointegrated implants placed in regenerated bone for up to 133 months in function.
A retrospective analysis of a group of 607 titanium plasma-sprayed cylindric implants placed in regenerated bone, the success and failure rates of which were previously reported at 6 to 51 months in function, were assessed.
The implants demonstrated cumulative success rates of 97.2% for the maxilla and 97.4% for the mandible, yielding an overall cumulative success rate of 97.4% for up to 133 months in function.
Titanium plasma-sprayed osseointegrated implants of various diameters, lengths, and designs, utilized in a variety of clinical scenarios, demonstrated functional cumulative success rates comparable to those of implants placed in nonregenerated host bone for extended periods of time in this patient population.
Numerous problems have been reported following various therapies used to attach natural teeth to implants beneath a fixed prosthesis. This study documents the results of 843 consecutive patients treated with 1,206 natural tooth/implant-supported prostheses utilizing 3,096 screw-fixed attachments. After 3 to 14 years in function, only 9 intrusion problems were noted. All problems were associated with fractured or lost screws. This report demonstrates the efficacy of such a treatment approach when a natural tooth/implant-supported fixed prosthesis is contemplated.
The purpose of this in vitro study was to investigate the effect of impression technique and implant angulation on the impression accuracy of external- and internal-connection implants using a novel experimental device.
Materials and methods:
An experimental device was designed and fabricated to make in vitro impressions by means of open- and closed-tray techniques. Impressions of eight implants with two different connections (four external-hex and four internal-hex) at three angulations (0, 15, and 25 degrees) were made using a medium-consistency polyether material. Evaluation of implant impression accuracy was carried out by directly measuring the difference in coordinate values between the implant body/impression coping positioned on the base and the impression coping/laboratory analog positioned in the impression using a touch-probe coordinate measuring machine. Experimental data were analyzed by two-way analysis of variance. The significance level of all hypothesis testing procedures was set at P<.05.
The results showed that: (1) for implants with external connections, impression accuracy is not significantly affected by the impression technique, implant angulation, or their interaction; and (2) for implants with internal connections, impression accuracy is significantly affected only by implant angulation: Impression inaccuracy was greater at the 25-degree implant angulation.
Within the limitations of this in vitro study, the open- and closed-tray techniques had no effect on the accuracy of multiple implant impressions. The interaction between impression technique and implant angulation was also not significant. However, implant angulation significantly affected the impression accuracy when implants with internal connections were used.
This study was intended to provide a report of experience and results with Frialit-2 implants used for single-tooth replacement.
Over a 7-year period (1994-2000), 146 single-tooth implants (84 maxilla, 62 mandible) were placed in 112 patients (67 females, 45 males; 31.2 +/- 16.4 years). The sites included maxillary anterior teeth (n = 38) as well as the mandibular premolars and molars (n = 57). Ninety-three crowns were cemented and 53 crowns were screw mounted (22 with vertical, 31 with horizontal screws) on standard abutments. The follow-up time varied between 3 and 80 months (35.8 +/- 16.5 months).
Two implants (1.4%) were lost, 1 during early loading and the other after 6 years. The most frequent prosthetic complication was isolated crown loosening of cemented crowns requiring recementation of 9 crowns (9.9%). Crowns with vertical screws showed no crown and/or screw loosening. Four crowns (2.8%) were replaced because of ceramic fracture.
Peri-implant soft tissue condition, bone resorption, and Periotest values indicated satisfactory results. The cumulative implant survival rate during the follow-up period was 97.3%, and that of the crowns 96.4% (total cumulative survival rate 93.7%).
With the low number of abutment screw loosenings (3.5%), the deep internal hexagonal retention compared favorably to external retention methods. The predominant use of long implants (98.4% > or = 13 mm) allowed a favorable implant/crown ratio with the potential for problem-free, long-term results.
Resonance frequency analysis (RFA) is a quantitative method for the measurement of implant stability. Information about the significance of RFA measurements and the relationship between RFA values and implant osseointegration, success, or failure is important from a clinical point of view. In a previous study the authors observed a strong correlation between RFA values and mineralized bone-implant contact percentage in implants retrieved after 6 months. The aim of the present histologic and histomorphometric study was to determine whether the same correlation existed at earlier time points, specifically in implants retrieved after 4 or 8 weeks.
Sixteen implants, all with a sandblasted and acid-etched surface, were evaluated in the present study. The implants were retrieved for different reasons after 4 or 8 weeks of healing with a 5-mm trephine bur and immersed in 10% buffered formalin to be processed for histology.
A statistically insignificant correlation was detected between RFA values and mineralized bone-implant contact percentage (P = or < .5502) using the Friedman and Spearman tests.
RFA should reflect the bone anchorage of the implant; however, the relationship between bone structure and RFA is not fully understood.
Two polymorphisms in the promoter region of human MMP-1 gene, an insertion of a guanine at position -1607 and A-519G substitution, have been shown to increase the transcriptional activity of these matrix metalloproteinases (MMPs). The objective of this study was to investigate the possible relationship between these polymorphisms and early implant failure.
A sample of 104 nonsmokers was divided into 2 groups: a test group comprising 44 patients with 1 or more early failed implants and a control group consisting of 60 individuals with 1 or more healthy implants. Genomic DNA from oral mucosa was amplified by polymerase chain reaction and analyzed by restriction endonucleases. The significance of the differences in observed frequencies of polymorphisms were assessed by chi2 tests.
The G-1607GG polymorphism with the genotype G/G was observed at a frequency of 62% in the control group, while in the test group this genotype was noted in 34% of the individuals (P = .011). The allele G was found at a frequency of 75% in control group and 61.66% in the test group (P = .05). No significant differences were seen in the genotypes and allele frequencies in the A-519G polymorphism among the groups (P = .064 and P = .124, respectively). The distribution of the haplotypes arranged as alleles and genotypes showed a significant difference between control and test groups (P = .031 and P = .002, respectively).
On the basis of this study of 60 patients who experienced no implant failure and 44 patients who experienced implant failure, the results suggest that G-1607GG polymorphism in MMP-1 gene is associated with early implant failure, while A-519G polymorphism in MMP-1 gene does not show a significant relationship with implant loss. This study also suggests that haplotypes G-1607GG and A-519G of MMP-1 may be associated with the osseointegration process.
The purpose of the article was to evaluate the survival rates of TiUnite implants and then compare them to a previous similar study of machined-surface implants.
This report presents the results of 82 consecutive patients treated since the introduction of Nobel Biocare's TiUnite surface. The patients were treated with complete-arch restorations using bilateral pterygomaxillary implants in edentulous maxillae. A total of 840 implants were placed in immediate extraction or healed sites, with a mean of 10 implants placed per patient.
In all, 826 of the 840 implants osseointegrated, for a cumulative survival rate (CSR) of 98.3%. One hundred fifty-eight of 164 pterygomaxillary implants successfully osseointegrated, yielding a 96.3% survival rate.
The results of this complete-arch maxillary prospective study suggest that Brånemark System TiUnite implants are more predicable than implants with a machined surface. Compared to a similar 1999 study in which the survival rate for machined-surface implants was 92.1%, the present study had a significantly higher survival rate of 98.6% with the TiUnite surface (P < .001). In the pterygomaxillary region, there was an increase of 8% with the TiUnite surface as opposed to the machined surface (P < .001). In addition, 62% of the implants in the present study were immediately loaded, compared to 0% in the machined-surface implant study. The titanium oxide surface appears to assist the healing response of the bone-implant interface.
To analyze and characterize the predominant bacterial flora associated with peri-implantitis by using culture techniques under obligate anaerobic conditions and 16S rDNA gene sequences.
Materials and methods:
Subgingival bacterial specimens were taken from 30 patients: control (n = 15), consisting of patients with only healthy implants; and test (n = 15), consisting of patients with peri-implantitis. In both groups, subgingival bacterial specimens were taken from the deepest sites. An anaerobic glove box system was used to cultivate bacterial strains. The bacterial strains were identified by 16S rDNA genebased polymerase chain reaction and comparison of the gene sequences.
Peri-implantitis sites had approximately 10-fold higher mean colony forming units (per milliliter) than healthy implant sites. A total of 69 different bacterial species were identified in the peri-implantitis sites and 53 in the healthy implant sites. The predominant bacterial species in the peri-implantitis sites were Eubacterium nodatum, E. brachy, E. saphenum, Filifactor alocis, Slackia exigua, Parascardovia denticolens, Prevotella intermedia, Fusobacterium nucleatum, Porphyromonas gingivalis, Centipeda periodontii, and Parvimonas micra. The predominant bacteria in healthy implant sites apart from Streptococcus were Pseudoramibacter alactolyticus, Veillonella species, Actinomyces israelii, Actinomyces species, Propionibacterium acnes, and Parvimonas micra.
These results suggest that the environment in the depths of the sulcus showing peri-implantitis is well suited for growth of obligate anaerobic bacteria. The present study demonstrated that the sulcus around oral implants with peri-implantitis harbors high levels of asaccharolytic anaerobic gram-positive rods (AAGPRs) such as E. nodatum, E. brachy, E. saphenum, Filifactor alocis, Slackia exigua, and gram-negative anaerobic rods, suggesting that conventional periodontopathic bacteria are not the only periodontal pathogens active in peri-implantitis, and that AAGPRs may also play an important role.
Piezoelectric osteotomy is based on ultrasonic vibration of an osteotomic device that permits precise cutting of bone structures without cutting adjacent soft tissues. To date, however, there have been no studies of the outcome and complications of alveolar distraction for piezoelectric osteotomy versus conventional osteotomy. The present study evaluated piezoelectric versus conventional osteotomy in alveolar distraction.
A retrospective study was performed on all patients of the authors who requested dental implants and who after preliminary evaluation were judged to require alveolar distraction osteogenesis for rehabilitation of edentulous mandibular regions. The distraction was performed using the same distraction system in all cases, but with the osteotomy performed either by conventional techniques using rotary instruments and chisels (conventional osteotomy group, n = 11), or by piezoelectric osteotomy using the Piezosurgery system (Mectron Medical Technology; Carasco, Genoa, Italy; n = 6). The 17 distractions were compared with respect to patient age, patient sex, intra- and postoperative complications, degree of surgical difficulty, postdistraction morphology of the alveolar ridge, and rehabilitation success rate.
Both surgical difficulty (as measured by the number of surgical instruments required) and the incidence of intraoperative complications were significantly lower in the piezoelectric osteotomy group than in the conventional osteotomy group. However, postdistraction morphology of the alveolar ridge (as determined at implant placement) was worse in the piezoelectric osteotomy group than in the conventional osteotomy group (P = .072). The overall rehabilitation success rate was 100% in the conventional osteotomy group versus only 66.7% (4 of 6 cases) in the piezoelectric osteotomy group.
The use of piezoelectric osteotomy in alveolar distraction appears to simplify surgery and reduce the incidence of intraoperative complications. However, results also suggest that piezoelectric osteotomy increases the risk of postoperative and postdistraction complications and reduces the overall rehabilitation success rate.
Severe bone atrophy in the mandible may result in weakening of the jaw, unstable dentures, and dysfunction of the inferior alveolar nerve. These conditions were diagnosed in a 65-year-old woman who presented with a severely resorbed mandible. The interforaminal region of the mandible was augmented with an onlay graft harvested from the iliac crest. Four dental implants stabilized the graft by anchoring it inferiorly to the residual mandibular basal bone. Implants later served as abutments for a fixed 12-unit implant-supported prosthesis. The patient was followed for 17 years, during which the mandibular prosthesis was replaced twice. Despite the initial questionable prognosis, oral rehabilitation was successful, with no detectable clinical signs of bone loss over the 17-year follow-up period.
As part of an ongoing prospective study, the treatment of peri-implantitis defects using autogenous bone grafts was evaluated. This present report is based on data from 25 ITI screw implants in 17 patients with progressive peri-implant tissue destruction during the maintenance phase. Treatment of these lesions included raising flaps, removal of the surrounding granulation tissue, and air-polishing of the implant surface. Subsequently, corticocancellous bone grafts or particulate bone were placed into the peri-implant osseous defects, and the flaps were sutured around the cervical segment of the implants, allowing for transmucosal healing. Two of the 25 cases resulted in a negative outcome of the procedure. One of the transplants had to be removed 40 days after augmentation because of flap dehiscence and graft mobility. In another patient, the healing period was uneventful until the re-entry surgery, but when the site was reopened, the total graft volume was resorbed. The primary therapeutic success at re-entry surgery evaluated by intraoperative measurements resulted in a median defect depth reduction of 6.9 to 0.7 mm (P = .001), corresponding to a bone repair of 90%. The change in defect width was 1.9 mm (P = .002, repair 100%). A positive result of the reconstructive therapy has been observed during a re-evaluation time of up to 3 years. Median marginal bone loss was reduced from 6.2 to 2.3 mm after 2 and 3 years, respectively. The median vertical bone resorption of 4.5 mm was completely repaired. The crevicular fluid volume, a parameter of the level of marginal inflammation, along with probing depths and attachment levels, were reduced to a physiologic rate. The implant observation period until the first appearance of the lesion seems to be crucial to the effectiveness of the therapy. Early failures appearing within the first 2 years after implant placement showed a more stable therapeutic result over time.
This retrospective study sought to demonstrate the outcome of maxillary sinus elevation surgery in a series of 177 procedures performed over 12 years and to determine the existence of variables that could independently predict implant survival.
A retrospective descriptive and analytic study of a series of maxillary sinus elevation procedures performed between 1996 and 2007 was undertaken. The sample was composed of patients with severe atrophy of the posterior maxilla who had been rehabilitated with osseointegrated implants placed in grafted maxillary sinuses. Several features of the patients (smoking habit, presence of comorbidities, and previous oral carcinoma) and of the surgical procedure (grafting material, associated procedures, associated materials, simultaneous/delayed implant placement, and complications) related to implant survival or failure were monitored during the follow-up period. Implant survival and the existence of variables that could predict implant survival independently were analyzed statistically.
One hundred seventy-seven sinus augmentation procedures were performed in 119 consecutive patients (mean age 50.02 years; SD 11.5). Of the 272 implants placed in sinus-augmented regions, 19 were lost. The mean follow-up period was 60.7 months (SD 36.5). The overall cumulative implant survival rate was 93% after 5 years. The multivariate analysis showed that the presence of complications related to the sinus augmentation procedure (membrane perforation and sinusitis) and peri-implantitis were factors in predicting implant failure.
On the basis of this retrospective analysis, it might be concluded that sinus augmentation is a very versatile procedure. Its efficacy and predictability in terms of implant survival rate is extremely high and independent of the graft material, surgical technique, associated comorbidities, smoking habits, and timing of implant placement. Complications such as membrane perforation, sinusitis, and peri-implantitis appeared to influence implant failure.
This article provides preliminary clinical results on the Osseotite NT implant, which was developed to simplify surgical procedure and cover an extended range of indications. Placement characteristics of NT and standard Osseotite implants were also compared in an in vitro study.
The in vitro placement characteristics of NT and standard Osseotite implants of 4.0 mm diameter and 8.5 to 15 mm in length were compared. In addition, a total of 182 NT implants (96 maxillary and 86 mandibular) were placed in 92 patients; of these, 87.9% were placed using a 1-stage technique. The implants were placed in healed sites (43.9%), fresh extraction sockets (37.4%), or recent extraction sites (2 months postextraction) (18.7%). Before restoration, healing times of 3 to 4 months in the mandible and 5 to 6 months in the maxilla were allowed. The entered implant length in the osteotomy site before contacting the bony walls (EILOS) was compared, as well as the number of turns and the time required to seat the implants. Cumulative survival rates (CSRs) were calculated for up to 18 months of follow-up after surgery.
The EILOS was between 47.3% and 57.6% of implant length for the NT implants; for the standard implants, it was between 12.0% and 21.2%. With the NT implants, the number of turns and the placement time were reduced by 61% to 64% and 61% to 65%, respectively. In the clinical study, 4 implants failed during the healing period; none failed after prosthesis placement. The CSR was 97.79% for implants placed into fresh or recent extraction sites; in healed sites, the CSR was 98.75%. The cumulative prosthetic success rate was 100%.
This new implant design is seated with special drills; the drilling sequence requires less time and less torque than that used for standard implants. The low failure rate after prosthetic loading was consistent with that observed for standard Osseotite implants.
These preliminary data suggest that the NT implant can be predictable in healed sites and fresh or relatively recent extraction sockets.
The purpose of this study was to evaluate and compare the long-term performance of fixed partial prostheses supported by 2 or 3 implants.
All patients treated with fixed partial prostheses supported by either 2 or 3 implants during the period 1985 to 1998 were included in this retrospective report. Annual clinical follow-up examinations were performed, with special attention to stability of the prostheses and peri-implant and occlusal conditions. Radiographic examination was performed when the prostheses were delivered (year 0) and subsequently at 1-year, 5-year, and 10-year examinations.
A total of 178 patients had received fixed partial prostheses (FPPs) during this period of whom 123 (77 women and 46 men) were available for follow-up (mean age = 65 years, range 32-91). These 123 patients received a total of 146 implant-supported FPPs (63 two-implant- and 83 three-implant-supported) supported by 375 implants. The mean observation periods for the 2- and 3-implant-supported restorations were 9.6 years and 9.4 years (range, 5 to 18 years), respectively. Survival rates for the 2- and 3-implant-supported prostheses were 96.8% and 97.6%, respectively. The implant survival rate after loading was 98.4% for both groups. The mean bone loss at the 5-year follow-up was 0.3 mm for the 2 groups. No significant differences in bone loss (P > .05), implant failure rate (P > .05), or incidence of mechanical complications (P > .05) were found between the 2 prosthesis designs. The complications differed, significantly, with more loose gold and abutment screws in the 2-implant-supported group (P < .05) and more porcelain fractures in the 3-implant-supported group (P < .05).
The 2-implant-supported partial prostheses exhibited long-term clinical performance comparable to prostheses supported by 3 implants.
This prospective randomized matched-pair controlled trial aimed to evaluate marginal bone levels and soft tissue alterations at implants restored according to the platform-switching concept with a new inward-inclined platform and compare them with external-hexagon implants.
Materials and methods:
Traditional external-hexagon (control group) implants and inward-inclined platform implants (test group), all with the same implant body geometry and 13 mm in length, were inserted in a standardized manner in the posterior maxillae of 40 patients. Radiographic bone levels were measured by two independent examiners after 6, 12, and 18 months of prosthetic loading. Buccal soft tissue height was measured at the time of abutment connection and 18 months later.
After 18 months of loading, all 80 implants were clinically osseointegrated in the 40 participating patients. Radiographic evaluation showed mean bone losses of 0.5 ± 0.1 mm (range, 0.3 to 0.7 mm) and 1.6 ± 0.3 mm (range, 1.1 to 2.2 mm) for test and control implants, respectively. Soft tissue height showed a significant mean decrease of 2.4 mm in the control group, compared to 0.6 mm around the test implants.
After 18 months, significantly greater bone loss was observed at implants restored according to the conventional external-hexagon protocol compared to the platform-switching concept. In addition, decreased soft tissue height was associated with the external-hexagon implants versus the platform-switched implants.
The purpose of this study was to assess the survival rates and interproximal bone levels for Osseotite implants that were restored with fixed provisional crowns without occlusion immediately after implant placement.
Ninety-three implants were placed in 38 partially edentulous patients. All implants were immediately restored with prefabricated abutments and cement-retained provisional crowns without centric or eccentric occlusal contacts. The implants were restored with definitive restorations approximately 8 to 12 weeks after implant placement. All patients included in the study were followed for at least 18 months after implant placement (average 20.3 months).
Seventy-seven of the 93 implants satisfied the inclusion criteria. Seventy-five implants became osseointegrated. The overall survival rate was 97.4%. Radiographic bone loss 18 months after implant placement (the mean of both interproximal surfaces) was 0.76 mm. The exact binomial confidence interval was 0.32% to 9.07%. For the exact binomial test with the null hypothesis proportion = .05, P was .3334 and was not statistically significant.
Immediate nonocclusal loading of single-unit dental implants differs from immediate loading of multiple, splinted implants. Unsplinted, restored implants without occlusal loading may still be subject to lateral and occlusal loads secondary to the proximate location of the food bolus. Immediate restoration of dental implants significantly reduces treatment time and may be beneficial in reducing the morbidity associated with loss of teeth, contraction of the alveolus, and loss of interdental papillae associated with the traditional method of treatment following tooth loss.
The results of this study suggest that immediate restoration of Osseotite implants can be accomplished with results that are similar to the results obtained with the traditional 1- or 2-stage surgical, unloaded healing protocols.
Nitrite is a stable end-product of nitric oxide oxidation. The aim of the present study was to quantitatively analyze peri-implant sulcular fluid (PISF) nitrite levels in a longitudinal study design to evaluate the potential changes in nitric oxide metabolism in relation to the clinical status of the peri-implant site and the loading style of the dental implants.
A total of 34 implants, either early loaded (EL) or delayed loaded (DL), in 17 patients were followed up for a period of 18 months. Clinical parameters were recorded, PISF samples were obtained, and PISF nitrite levels were spectrophotometrically determined. Clinical measurements and nitrite analysis were repeated at 1, 3, 6, 9, 12, and 18 months.
Despite the gradual decrease in clinical parameters, fluctuations in PISF total nitrite levels were observed during follow-up. The pattern of nitric oxide metabolism, as reflected by PISF nitrite levels, also demonstrated differences between EL and DL implants that diminished toward the end of the experimental period.
Although the presence of clinical and subclinical gingival inflammation contributes to the PISF total nitrite levels, nitric oxide metabolism is also associated with healing and bone remodeling, and the pattern of loading seemed to have an impact on nitric oxide production at dental implant sites.
Nitric oxide production at dental implant sites seems to be tightly regulated to enable the maintenance of peri-implant bone.
The purpose of this study was to evaluate a specific protocol using four implants to support immediately loaded fixed prostheses to restore edentulous and partially edentulous mandibles and report on the outcome after 1 year of function with the definitive prostheses.
A retrospective study was conducted of all patients who were treated between June 2008 and December 2010 with fixed prostheses that were loaded immediately after placement of implants. The provisional prostheses were later replaced with computer-aided design/computer-assisted manufacture titanium frames supporting acrylic resin and denture teeth in the definitive prosthesis. All patients were followed for a minimum of 12 months and were assessed for implant survival and prosthetic performance, with descriptive statistics utilized to demonstrate results.
One hundred eighty-three consecutive patients received immediately loaded axial and tilted implants according to the defined protocol. One implant failed, resulting in a 99.86% implant success rate. There were two catastrophic prosthetic failures (fracture of the titanium framework), for a 98.9% prosthetic success rate. Three patients (1.6%) presented with fracture of a prosthetic mandibular incisor tooth. No prosthetic screw loosening or fractures were seen. Radiographic evaluation revealed no major bone loss around dental implants.
Based on this retrospective study, the following conclusions can be drawn: (1) this technique appears to provide a highly predictable implant performance; (2) it is necessary to critically evaluate framework design, especially around the connectors for cantilever extensions around the most distal implants; and (3) minor complications related to acrylic resin tooth fracture may be anticipated during the early phases of prosthetic treatment.
The aim of this review was to evaluate the clinical outcomes for the different time points of implant placement following tooth extraction.
A PubMed search and a hand search of selected journals were performed to identify clinical studies published in English that reported on outcomes of implants in postextraction sites. Only studies that included 10 or more patients were accepted. For implant success/survival outcomes, only studies with a mean follow-up period of at least 12 months from the time of implant placement were included. The following outcomes were identified: (1) change in peri-implant defect dimension, (2) implant survival and success, and (3) esthetic outcomes.
Of 1,107 abstracts and 170 full-text articles considered, 91 studies met the inclusion criteria for this review. Bone augmentation procedures are effective in promoting bone fill and defect resolution at implants in postextraction sites, and are more successful with immediate (type 1) and early placement (type 2 and type 3) than with late placement (type 4). The majority of studies reported survival rates of over 95%. Similar survival rates were observed for immediate (type 1) and early (type 2) placement. Recession of the facial mucosal margin is common with immediate (type 1) placement. Risk indicators included a thin tissue biotype, a facial malposition of the implant, and a thin or damaged facial bone wall. Early implant placement (type 2 and type 3) is associated with a lower frequency of mucosal recession compared to immediate placement (type 1).
A retrospective study was performed to evaluate the feasibility of simultaneous use of immediately loaded zygomatic and mandibular implants for full maxillomandibular restoration.
Materials and methods:
A total of 40 zygomatic and 112 conventional implants were placed in 19 edentulous and partially edentulous patients and restored with full-arch acrylic resin prostheses within 3 hours of surgery. Implant insertion torque values were between 35 and 45 Ncm.
During the 1-year follow-up period, none of the 19 patients experienced implant or prosthesis failures. The patients did not experience any sinus infections or any other surgical complications from the performed procedures.
Zygomatic and conventional implants can be simultaneously placed in the maxilla and mandible and successfully loaded with an acrylic resin prosthesis using the All-on-Four concept.
This prospective case series evaluated the use of a new titanium-reinforced nonresorbable membrane (high-density polytetrafluoroethylene), in combination with a mixture of anorganic bovine bone-derived mineral (ABBM) and autogenous particulated bone, for vertical augmentation of deficient alveolar ridges.
Materials and methods:
A mixture of ABBM and autogenous particulated bone was used for vertical ridge augmentation and covered with a new titanium-reinforced nonresorbable membrane. Ridge measurements were obtained before and after the procedure, complications were recorded, and biopsy specimens were taken for histologic examination.
Twenty vertical ridge augmentation procedures were carried out in 19 patients. All treated defect sites exhibited excellent bone formation, with an average bone gain of 5.45 mm (standard deviation 1.93 mm). The healing period was uneventful, and no complications were observed. Eight specimens were examined histologically; on average, autogenous or regenerated bone represented 36.6% of the specimens, ABBM 16.6%, and marrow space 46.8%. No inflammatory responses or foreign-body reactions were noted in the specimens.
The treatment of vertically deficient alveolar ridges with guided bone regeneration using a mixture of autogenous bone and ABBM and a new titanium-reinforced nonresorbable membrane can be considered successful.
Dental implants generally provide good results as replacements for missing teeth, but a few patients experience implant failure. The aim of this retrospective study was to analyze the characteristics and causes of implant failures in hopes of reducing future failures.
Materials and methods:
Patients who received one or more implants at the Dental Hospital of Yonsei University College of Dentistry between February 1991 and May 2009 were included in this study. Data including age, sex, medical history, habits (eg, smoking and drinking), bone quality, primary stability, implant size, implant surface, additional surgical procedures, prosthetic type, clinical symptoms, implant failure date, and causes of implant failure were obtained through a chart review. Follow-up radiographs were compared to those obtained at baseline. The Pearson chi-square test and Fisher exact test were used to evaluate the correlations between risk factors and implant failure.
In total, 879 patients received 2,796 implants; 150 implants in 91 patients had failed. Early and late implant failures occurred with 86 (57.3%) and 64 (42.7%) implants, respectively. The main causes of early and late implant failures were inflammation (47%) and overloading (53%), respectively. When the cause of early implant failure was inflammation, the failure rate was significantly higher for implants in the anterior maxilla; implants with poor primary stability, a machined surface, or a length exceeding 15 mm; and implants placed with a reconstructive procedure and two-stage surgery. When late implant failure was caused by overloading, the failure rate was significantly higher for implants with a machined surface, placed with a reconstructive procedure and/or two-stage surgery, and supporting telescopic dentures.
Within the limitations of this study, the major causes of implant failure are inflammation and overloading, and they differ between early and late implant failures.
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.
The present study was undertaken to determine the feasibility of using primary stability as a predictor of implant success in patients whose implants were immediately loaded.
The study included 40 patients, in whom a total of 190 implants were placed, 102 in maxillary sites and 88 in mandibular sites. All were loaded within 72 hours of placement. Sixteen patients were completely edentulous in the mandible and/or the maxilla. The remaining 24, who were partially edentulous, received fixed partial dentures or single-implant restorations. All of the definitive implant restorations were screw retained. The criterion for loading was clinical judgment of primary stability, verified by a "screw test." Impressions were made after implant placement to facilitate the fabrication of a laboratory-made heat-processed provisional restoration from acrylic resin. Following a 4-month period for osseointegration and soft tissue healing, definitive fixed prostheses were fabricated.
There were no surgical complications. After 1 to 2 years, all 190 implants had survived and were considered 100% successful, as determined by independent testing of mobility and radiographic evidence of osseointegration. In 4 patients, fracture of the provisional restoration occurred during the healing period.
Clinical research has shown that immediate loading is a viable treatment modality. The favorable success rate reported in this study for rough-surfaced implants suggests that adherence to a protocol, an important parameter of which is primary stability above 32 Ncm, can lead to osseointegration.
The results of this limited investigation suggest that patients who are partially or completely edentulous may be immediately restored with implants and fixed provisional restorations, provided that the dental implants are adequately stable immediately after their surgical placement. This alternative therapeutic approach did not appear to affect the up-to-2-year survival of the implants in this patient population.