Clinical reports of feldspathic porcelain veneered-zirconia crowns placed on teeth with knife-edge marginal finish lines have recently been presented but with data available for only a limited number of crowns in the anterior maxilla.
This retrospective study evaluated the clinical success and survival of feldspathic porcelain veneered-zirconia crowns fabricated with knife-edge margins in a private practice.
One hundred and two teeth (51 anterior, 51 posterior) were prepared with knife-edge margins and restored with feldspathic porcelain veneered-zirconia crowns. The modified California Dental Association (CDA) criteria were used to clinically evaluate subjects recalled between May and December 2010. Data were analyzed with descriptive statistics.
The mean follow-up time was 20.9 months (SD, 13.6; range, 10-72). One tooth had to be extracted because of an endodontic problem not related with the restoration, 2 crowns had minor chipping of the veneering porcelain, while no crowns exhibited fracture of the zirconia core.
In this retrospective evaluation, feldspathic porcelain veneered-zirconia crowns with knife-edge margins provided clinical performance similar to that reported with other margin designs.
Treatment of tooth loss in the anterior maxilla can involve difficult functional, esthetic, and psychologic problems, especially in young patients with otherwise good dentition.
The purpose of this study was to provide a preliminary comparative evaluation of two implants (ITI and Astra) in single-tooth restorations.
This prospective study of 102 single-tooth replacements with 56 ITI and 46 Astra dental implants was performed in 82 patients at the Finnish Student Health Service Foundation. One Astra implant was lost before loading. The overall survival rate of the implants was 97.8% for Astra implants and 100% for the ITI system. After the initial healing period of at least 6 months, the remaining 101 implants (56 ITI, 45 Astra) were free of periimplant infection and revealed no detectable mobility. Radiographs did not reveal signs of periimplant radiolucencies. All 101 implants received single-tooth crowns.
Periimplant parameters and acceptable implant function were examined and demonstrated satisfactory results with preestablished clinical parameters and radiographs at 1 year. During the observation time the mean marginal bone loss was 0.13 mm with Astra implants and 0.11 mm with ITI implants. Subjectively all patients were satisfied with their single-tooth restorations supported by either ITI or Astra dental implants.
The favorable results of this short-term study support the application of the two implant systems for single-tooth restorations, especially in the anterior region of the maxilla.
Plaque on dentures may foster the occurrence of denture stomatitis and periodontal diseases in gingival tissues adjacent to partial dentures. Thus, it is beneficial for dental materials to have a low susceptibility to plaque adhesion.
The purpose of this study was to evaluate the susceptibility of commonly used artificial teeth to adhesion of the oral bacterium Streptococcus mutans.
Fifteen specimens each of 12 different artificial teeth were prepared by cutting standardized slabs from the buccal tooth surfaces. After normalizing size (round specimens, diameter of 5 mm, 2 mm thick), polishing (grinding paper, grain 1000 and 4000; universal polishing paste), and assessing surface roughness with a profilometric contact surface measurement device, specimens were incubated with Streptococcus mutans NCTC 10449 suspension for 2.5 hours at 37 degrees C. A veneering composite resin (Sinfony) was used as a control. Adherent bacteria were quantified using a fluorometric assay (Resazurin reduction); relative fluorescence intensity correlates linearly with the number of adherent bacteria. Medians and 25%/75% percentiles were calculated, and statistical analysis was performed using the Kruskal-Wallis test and the Bonferroni-adjusted Mann-Whitney U test.
The highest values, indicating high adhesion of streptococci, were observed for filler-supplemented teeth with median relative fluorescence values ranging from 6356 to 18,770. Similar values were recorded for a double cross-linked resin tooth (6444). Significantly lowest values, ranging from 1173 to 3974, were found for unfilled PMMA acrylic resin teeth and acrylic resin teeth with an interpenetrating network (1436).
Within the limitations of this study, it can be concluded that the adhesion of Streptococcus mutans to unfilled PMMA teeth and teeth with an interpenetrating network is lower than adhesion to artificial teeth supplemented with fillers or double cross-linked acrylic resin teeth.
Ti-10Ta-10Nb alloy is a promising alloy for metal ceramic crowns because of its good corrosion resistance and low cytotoxicity. However, more information is needed on the bond strength between this alloy and porcelain.
The purpose of this study was to compare the surface morphology, surface roughness, and bond strength of a Ti-10Ta-10Nb alloy, pure Ti, and a Ti-6Al-4V alloy.
Ti-10Ta-10Nb, pure Ti, and Ti-6Al-4V specimens (25 × 3 × 0.55 mm plate) were prepared and then divided into 6 groups (n=8) according to surface treatment. Group P (control group) was polished with SiC paper. Groups S50 and S250 were airborne-particle abraded with 50 μm and 250 μm aluminum oxide powder. Group HCl was immersed in 10% HCl aqueous solution, and Group HF was immersed in 17% HNO(3)/HF solution. Group TiN was coated with TiN. Atomic force microscopy was used to observe the surface roughness of the metal surface. Scanning electron microscopy was used to analyze the surface profile. A 3-point bending test was performed to evaluate the bond strength. Two-way analysis of variance (ANOVA) was performed to compare the roughness and bond strength and statistical differences were revealed by the Bonferroni post hoc test (α=.05).
There were significant differences in the surface roughness, surface profile, and bond strength of the Ti alloys according to the surface treatments. The groups with the higher mean surface roughness showed higher bond strength, but surface profile had a larger effect on the bond strength than surface roughness. Moreover, the bond strength of the Ti-10Ta-10Nb alloy was high.
Ti-10Ta-10Nb would be more suitable for a metal ceramic crown than pure Ti or Ti-6Al-4V, which have limited use because of their low bond strength to porcelain.
Soft denture liners are an important treatment option for patients who have chronic soreness associated with their prostheses. The objective of this study is to determine the tensile strength, elongation, hardness, tear strength, and tear energy of eight plasticized polymers or copolymers, two silicones, and one polyphosphazene fluoroelastomer. Tests were made on samples that were stored in a humidor for 24 hours before testing. The range of data is as follows: tensile strength, 8 to 85 kg/cm2; percent elongation, 150% to 542%; hardness, 25 to 95 Shore-A units; tear energy, 1.43 x 10(6) to 40.4 x 10(6) ergs/cm2; tear resistance, 2.6 to 26.3 kg/cm. It can be concluded that (1) the data obtained can be useful in characterizing the performance of soft denture liners, (2) there is considerable variability in the physical/mechanical properties of soft denture liners, and (3) the required essential properties for soft denture liners are as yet not known.
Soft denture-lining materials are an important treatment option for patients who have chronic soreness associated with dental prostheses. Three distinctly different types of materials are generally used. These are plasticized polymers or copolymers, silicones, or polyphosphazene fluoroelastomer. The acceptance of these materials by patients and dentists is variable. The objective of this study is to compare the tensile strength, percent elongation, hardness, tear strength, and tear energy of eight plasticized polymers or copolymers, two silicones, and one polyphosphazene fluoroelastomer. Tests were run at 24 hours after specimen preparation and repeated after 900 hours of accelerated aging in a Weather-Ometer device. The data indicated a wide range of physical properties for soft denture-lining materials and showed that accelerated aging dramatically affected the physical and mechanical properties of many of the elastomers. No soft denture liner proved to be superior to all others. The data obtained should provide clinicians with useful information for selecting soft denture lining materials for patients.
Implant-supported restorations in the partially edentulous jaw have been performed at the Mayo Clinic for more than 10 years. Clinical performance of the implants and the prostheses should be reported to ensure effectiveness of this procedure.
This retrospective study described results for implant survival, implant fracture rate, prosthetic complications, and design changes that may impact these results.
A retrospective chart review was conducted of all registered implant patients in a large multispecialty medical center. Patients with a partially edentulous jaw who had received endosseous implants to support and retain dental prostheses were included in this review. Implant survival and fracture, prosthetic complications, and demographic data were recorded and analyzed through Kaplan-Meier methods.
A total of 1170 implants were placed in four anatomic locations: anterior maxilla, posterior maxilla, anterior mandible, or posterior mandible. Location of implants was shown to have no effect on implant survival (p = 0.7398), implant fracture rates (p = 0.2385), screw loosening (p = 0.8253), or screw fracture (p = 0.2737). Development of new restorative components has resulted in significantly better rates of implant survival without fracture (p = 0.0054), screw function without loosening (p < 0.0001) and screw function without fracture (p = 0.0013). Implant survival seems to have been improved with the new components (p = 0.0513).
Implant survival in this study was independent of anatomic location of implants. Virtually all clinical performance factors were improved by design changes in implant restorative components that were brought to market in early 1991.
This article describes the clinical, radiographic, and histologic evaluation of 2 immediately loaded Vitallium blade-form implants retrieved from the posterior maxilla of 2 patients after 21 and 13 years of function. Neither implant demonstrated mobility or signs of pathosis, and both appeared to have integrated well with surrounding bone. The hydroxyapatite coating of the second implant, which was retrieved after 13 years of function, showed no dissolution. These observations suggest that immediately loaded dental implants have the potential to achieve and maintain osseointegration and that hydroxyapatite coatings can resist degradation over long-term service.
Noncarious cervical lesions are described as having a multifactorial cause, with occlusal trauma and toothbrush abrasion frequently mentioned as major factors. Finite element modeling studies have demonstrated a relocalization of occlusal stresses to the cervical area due to flexure of the crown. This may cause microcracking, especially under tensile stresses, that will lead to a loss of enamel and dentin in the cervical region. Clinical confirmation of an occlusal cause for noncarious cervical lesions has been difficult to obtain.
This study investigated whether occlusal wear was correlated with an increase in the size of noncarious cervical lesions.
Loss of contour at occlusal and cervical sites on 3 teeth of a single individual was measured using digital and visualization techniques at 3 time intervals over a 14-year time span. The 1983 baseline casts and 1991, 1994, and 1997 clinical impressions of a single adult patient with existing noncarious cervical lesions were replicated in epoxy. Surfaces of all replicas were digitized with a contact digitizing system. Sequential digitized surfaces were fit together and analyzed using AnSur-NT surface analysis software. Clinical losses of surface contour by volume and depth of the left mandibular first molar and first and second premolars were recorded.
Nine measurements of cervical volume loss (range 0.9 to 11.5 mm(3)) and 9 corresponding measurements of occlusal volume loss (range 0.39 to 7.79 mm(3)) were made. The correlation between occlusal and cervical volume loss was strong (r(2)=0.98) and significant (P<.0001).
For the single adult patient in this study, there was a direct correlation between occlusal wear and the growth of noncarious cervical lesions.
Since 1973 Alberta's dental plan for the elderly has made government-sponsored, premium-free, comprehensive dental care available from both dentists and denturists in private practice to all residents older than 64 years. This article is based on an analysis that covered 260,000 patients from 1978 to 1992. It presents the frequency, nature, and cost of denture replacements to patients and pays particular attention to replacements administered within the allowable 5-year time limit stated by the plan for complete and removable partial dentures. During the 14-year period, about 55,000 dentures were replaced; 47% of these were replaced in the year after the individual's 5-year time limit had expired. Within the 5-year limit 1974 dentures were replaced at a nominal cost of +1.09 million, with nearly one half of these costs being attributed to denturists. Relative to the total number of dentures provided during the 14-year period, the denture replacement rate for dentists was 7% to 8%, and for denturists it was nearly three times greater at 21% to 22%. The replacement process included many crossovers by patients between dentists and denturists; for example, nearly one quarter of the 190 complete dentures initially provided by dentists were replaced by denturists within 5 years.
The influence of different restorative design features on the long-term survival of Dicor glass-ceramic restorations is not well understood.
This study examined the relationship of different types of restorations and methods of preparation with the survival of Dicor glass-ceramic restorations functioning in vivo.
A total of 1444 Dicor glass-ceramic restorations were placed on the teeth of 417 adults. Failure was defined as a restoration that required remake because of material fracture. Survival of restorations of different types and with different methods of preparation was described by using Kaplan Meier survivor functions. Statistical significance between restoration type and preparation method was determined with the log rank test.
Probability of survival of a typical partial coverage restoration was 92% at 11.3 years. There was no statistically significant difference between the survival of inlay or onlay restorations. For the 91 cores used for pulpless teeth, none failed over a total cumulative monitoring period of 419 years. There was no significant difference in survival of acid-etched Dicor restorations that were placed on shoulder or chamfer preparations. Thickness measured at the midpoint of the labial, lingual, mesial, distal, and midocclusal surfaces did not relate to risk of failure.
The majority of Dicor glass-ceramic partial coverage inlay and onlay restorations and cores survived over time. Survival of restorations with either chamfer or shoulder preparations did not differ whether the restoration was acid-etched. Thickness of the restoration measured at the midaxial point of each surface did not relate to survival.
There are no long-term data on Dicor glass-ceramic restoration survival in the human oral cavity and the effect that different technical and clinical variables have on survival.
This prospective study examined the relationship of different clinical parameters on the survival of Dicor glass-ceramic restorations in the human oral cavity.
A total of 417 subjects (from 17 to 91 years of age) participated. All subjects required single unit fixed prosthodontics in any area of the mouth and/or 3-unit fixed partial dentures or cantilevered anterior restorations. They were offered the option of a gold or conventional metal-ceramic restoration, or a Dicor restoration with potentially improved esthetic results, better wear characteristics, and diminished oral plaque accumulation. Overall survival of the restorations was determined and the effect of various clinical parameters evaluated with Kaplan-Meier survival curves. Log rank tests were used to determine statistically significant differences among parameters.
For the 1444 units placed, 188 failures were recorded. Total time at risk for the units was 7319 years providing an estimated risk of 2.45% per year. Probabilities of survival of "typical" acid-etched Dicor and nonacid-etched Dicor restorations were 76% and 50%, respectively, at 14.1 years (P <.001). Probabilities of survival of typical acid-etched and nonacid-etched Dicor complete coverage restorations were virtually identical to those observed in the full data set. There was a 2.2 times greater risk of failure associated with the use of nonacid-etched Dicor complete coverage than acid-etched restorations (P <.01). Complete coverage restoration survival was highest in the incisor region and decreased to the molars in both arches. Second molars showed the highest failure rate. No complete coverage restorations failed on lateral incisors during the entire study. Probability of survival of a typical acid-etched Dicor complete coverage restoration in male subjects was 71%, and 75% for female subjects at 14.1 years (P <.01). The major difference appeared to be due to a greater failure rate in the maxillary arch of the male. Survivor functions of acid-etched Dicor complete coverage restorations for subjects in <33 years, 33 to 52 years, and 52 years age groups were 88% at 9 years, 62% at 14 years, and 82% at 14 years, respectively.
Dicor restorations can survive successfully over time with certain reservations. Long-term survival improved significantly when restorations were acid-etched before luting. Complete coverage restoration failures per year decreased from molars to incisors in both arches, suggesting that complete coverage restorations on molars represented a serious risk. No Dicor complete coverage restoration on lateral incisors failed during the study. Restorations failed less often in female than male subjects.
This report includes 14 patients with rhinocerebral mucormycosis treated at the UCLA Medical Center since 1970. This disease has an extremely high mortality and morbidity. It is of interest to dentists because of the common presenting symptoms of periorbital cellulitis and sinusitis and the occasional presenting symptoms of dental pain or subperiosteal swelling. It is of further interest because of the intraoral and extraoral midfacial defects that result from disease extension and the necessary surgical débridement. The resultant facial and oral defects are far more difficult to restore than similar defects secondary to resection of head and neck neoplasms.
In a 10-year, multicenter, double-blind clinical trial, comparisons of the clinical behavior of crown and fixed partial denture restorations were made between a gold alloy and four less costly alternative alloys. The endpoints of interest were (1) the development of unacceptable ratings on any of 11 individual prosthodontic criteria and an overall rating, (2) the removal of the restoration, and (3) an event combining unacceptable overall rating and restoration removal. Each of 630 patients had two restorations completed, one from gold-palladium alloy and the other from one of four alternative alloys. The patients were enrolled during a period of 3 1/2 years, with some patients followed up as long as 10 years after restoration. Analysis of the endpoints showed that one of the alternative alloys was significantly poorer than the other materials for certain criteria.
Comparison of mechanical properties of seven metal ceramic alloys in as-cast and heat-treated conditions resulted in significant differences. Tested alloys included one Au-Pd (control), three palladium-based, and three nickel-based alloys. Mechanical properties included strength, elongation, modulus, and microhardness. Twenty-four tensile bars were cast for each alloy. Twelve of the 24 bars for each alloy were randomly selected for heat treatment by the Ceramco technique. After heat treatment the Au-Pd alloy became stronger and harder and showed an increased elongation. The effects of heat treatment on the strength of the palladium-based alloys were variable, showing a decrease in hardness and an increase in elongation. The nickel-based alloys were weakened by the heat treatment and showed a decrease in hardness and an increase in elongation. Heat treatment did not significantly affect the modulus of any of the tested alloys.
We examined patients to find out whether they noticed the prevalence of metallic taste and set out to determine the association of metallic taste with demographic, medical, and dental factors. Data were collected as part of a Veterans Administration Cooperative Study investigating the suitability of alternative metal ceramic alloys as substitutes for alloys that contain gold. Crowns and fixed partial dentures were made from control and alternative alloys for accepted volunteer patients. A month after placement of the restorations and at regularly scheduled recall appointments, the patients were asked if they tasted a metallic flavor. Of the 2023 times the question was asked, 101 positive responses were given by 68 patients (46 reported metallic flavor once, and 22 reported it more than once). Results indicated that youth, sensitivity to heat and cold, bruxism, grinding, and an increasing number of restorative units were significantly related to metallic taste. For any given visit, about 5% of the patients reported tasting a metallic flavor regardless of the type of alloy that was used in the restoration. Metallic taste does not appear to be a problem with alternative alloys.
This analysis compared the precementation quality of metal ceramic restorations made from different alternative alloys after they had been returned from the central dental research laboratory. Ticon, Micro-Bond N/P2, Ceramalloy II, and W-1 materials were evaluated by use of 11 well-defined criteria and for overall performance. The evaluations were compared with those of Olympia, a gold-containing alloy, which served as the control. The results showed statistically significant differences between Olympia alloy and some of the alternative alloys for six of the 11 criteria. These differences, however, were not sufficient to be considered clinically significant (clinically detectable). In the comparison of their overall performances no statistically significant differences were found.
The primary objective of Veterans Administration Cooperative Studies Program No. 242 was to evaluate, in vitro and in vivo, the suitability of new dental materials and techniques used in making crowns and fixed partial dentures. Because inaccurate margins can lead to changes in the periodontal tissues and/or to recurrent caries, it is important to assess the accuracy of margins resulting from the use of new, improved materials or techniques. This segment of the project compared the marginal fit associated with the use of Dicor Crowns, Cerestore crowns, and porcelain-shoulder metal ceramic full coverage restorations using both quantitative and qualitative methods. Statistically significant differences were found among these materials following analysis of the quantitative data. The ranking in mean marginal opening from smallest to largest was: metal margins (27.5 microns), Dicor crowns (63.5 microns), porcelain shoulder restorations (66 microns), and Cerestore crowns (75 microns). The rank order based on the qualitative evaluation method was the same.
In 1980, the Veterans Administration Cooperative Studies Program No. 147 initiated a multicentered, multidisciplinary clinical study to evaluate the use of alternative alloys for porcelain-fused-to-metal restorations. This segment of the study compares the accumulation of dental plaque, over time, on restorations made from either Olympia or one of several alternative alloys, including W-1, Ceramalloy II, Micro-Bond N/P2, or Ticon in comparison to: (1) an unrestored tooth, which served as the periodontal control, (2) Olympia, the alloy control, and (3) among the alternative alloys. The restoration of approximately 800 teeth with fixed partial dentures/crowns was not found to contribute to plaque accumulation when measured by using the Löe and Silness plaque index. Statistically, more plaque was exhibited by the unrestored periodontal control tooth than by any of the restored teeth. No differences in plaque accumulation were observed between Olympia and the alternative alloys or among the alternative alloys themselves after 36 months of clinical use.
The rating system developed for this study combined ordinal and numerical scoring. The method involved the following: defining the critical criteria, defining the ordinal rating criteria for the assignment, assigning numerical scores for each individual criterion and totalling the scores for each restoration, adding an adjustment number, and scaling the results to the 0-to-10 range and rounding off to the nearest tenth. When tested on sample data gathered at the 12-month followup appointment, the new system elicited a finer discrimination of differences in the quality of the restorations. Although the system fully meets the needs of the specific project, it should not be considered an answer to the needs of all clinical investigations. It should be viewed as a different approach in the development of an acceptable clinical rating system.
The factors necessary for a comprehensive multidisciplinary, multicenter clinical study have been incorporated into CSP No. 147. The experimental design provides the potential for multiple laboratory and clinical data comparisons of alternative alloys. The study incorporates clinical performance observations with dental and medical histories that permit many unique correlations. This potential demonstrates the comprehensiveness of the CSP No. 147 study design and its contributions to clinical dental research in the evaluation of restorative materials.
Data were collected from 150 men and women complete-denture patients. Their jaw records were evaluated with a specially designed instruments. The extent of deviation of the maxillary and the mandibular ridges in the horizontal plane was calculated at various interridge distances, at a constant interalveolar crest-line angle of 80 degrees. It was found that: 1. Most patients of both sexes revealed a normal horizontal ridge relationship. 2. Next to the normal ridge relationship, there was a tendency for a unilateral cross-bite ridge relationship on the left sides of those patients who had recent extractions (up to 6 months previously). 3. True bilateral cross-bite ridge relationships were found only in those patients who gave a history of prolonged edentulousness. 4. The decision to arrange the posterior teeth in normal or cross-bite ridge relationship should take into consideration the deviations in the ridge relationship as well as the interridge distance. A method of evaluating interridge deviations in the horizontal plane in the posterior region of articulated jaw records of edentulous patients was developed.
There is sparse posttreatment evaluation of craniomandibular dysfunction (CMD). This study describes the use of an orthopedic interocclusal appliance with passive eruption for the treatment of CMD. The clinical results of 151 patients treated using the passive eruption procedures were assessed at a follow-up time averaging 1.75 years after treatment with a highly structured telephone interview questionnaire. The treated patient population was chronic, averaging 2.58 years in pain and 2.25 previously ineffective treatments for their CMD. Although this was a subjective inquiry, the treated patients confirmed significant reductions in symptoms, a decrease in pain and interference ratings, and reduced health care utilization. A subgroup of 38 patients who previously had no relief with flat-plane therapy exhibited similar positive results. Treatment failures were also assessed but were low. The results are discussed in terms of the patients' support of the efficacy of the passive eruption procedure, including the need for future research.
Porcelain fracture associated with an implant-supported, metal ceramic crown or fixed partial denture occurs at a higher rate than in tooth-supported restorations, according to the literature. Implant-specific and patient-specific causes of ceramic failure have not been fully evaluated.
The purpose of this retrospective study was to evaluate the potential statistical predictors for porcelain fracture of implant-supported, metal ceramic restorations.
Over a 6-month period, a consecutive series of patients having previously received implant-supported, metal ceramic fixed restorations were examined during periodic recall appointments. The number of supporting implants, number of dental units, type of restoration, date of prosthesis insertion, location in the dental arch, opposing dentition, type of occlusion, presence of parafunctional habits, use of an occlusal protective device, presence or absence of ceramic fractures, gender, and age were recorded for each patient. The generalized estimating equation (GEE) approach was used for the intrasubject correlated measurements analysis of categorical outcomes (presence or absence of ceramic fractures) to determine which patient- and implant-specific factors would predict porcelain fracture (alpha=.05).
Data were collected from 152 patients representing 998 dental units (390 single crowns and 94 fixed partial dentures) supported by 729 implants. Porcelain fractures of 94 dental units occurred in 35 patients. The fractures were significantly (P<.05) associated with opposing implant-supported metal ceramic restorations, bruxism, and not wearing a protective occlusal device. Metal ceramic prostheses (single crown or fixed partial dentures) had approximately 7 times higher odds of porcelain fracture (odds ratio (OR)=7.06; 95% confidence interval (CI): 2.57 to 19.37) and 13 times greater odds of a fracture requiring either repair or replacement (OR=13.95; 95% CI: 2.25 to 86.41) when in occlusion with another implant-supported restoration, as compared to opposing a natural tooth. In addition, patients exhibiting bruxism or not wearing an occlusal device had approximately 7 times higher odds (OR=7.23; 95% CI: 3.86 to 13.54), and 2 times higher odds (OR=1.92; 95% CI: 1.01 to 3.67) of porcelain fracture when compared to patients without bruxism and patients not wearing an occlusal device.
Implant-supported metal ceramic single crowns and fixed partial dentures were found to have a significantly higher risk of porcelain fracture in patients with bruxism habits, when a protective occlusal device was not used, and when the restoration opposed another implant-supported metal ceramic restoration.
A total of 19 hyperostoses underlying mandibular posterior fixed partial dentures were observed in 16 patients. In three patients the lesions were bilateral. Histologic examination of hyperostoses from eight patients showed that they were composed essentially of hyperplastic lamellar bone. Radiographic and clinical evidence suggested that subpontic hyperostoses are chronic, slow growing lesions with an exclusive predilection for the mandibular molar-premolar site. They appear to have variable growth rates and attain widely variable maximum size. The etiology of subpontic hyperostoses is unknown, but it is possible that inflammation, trauma, mandibular and occlusal function, and genetic factors, either individually or in combination, play a role in the initiation and development of these lesions. Subpontic hyperostoses have potential periodontal and restorative implications that may require their surgical removal.
The influence of different types of restorative design features on the long-term survival of Dicor glass-ceramic restorations is only partially understood.
This study examined the effect of different types of luting agents and preparation core structures on the survival of Dicor glass-ceramic restorations functioning in vivo.
A total of 1444 Dicor glass-ceramic restorations were placed on the teeth of 417 adults. Failure was defined as a restoration that required remake because of material fracture. The survival of restorations of different types, with different luting agents and preparation core structures, was described with Kaplan-Meier survival functions. The significance of differences in survival between different tooth or tooth-substitute preparation core structures and different luting agents was determined with the log-rank test.
The probability of survival of a typical acid-etched Dicor restoration luted to gold preparation core structures was 91% at 16 years compared with 75% for dentin preparation core structures (P<.01). The survival of acid-etched Dicor restorations luted to dentin preparations was significantly better than nonacid-etched restorations luted to dentin. Acid-etched Dicor restorations luted with resin composite exhibited a more favorable survival function than those luted with glass ionomer (P<.01) and zinc phosphate (P<.05). Differences between restorations luted with glass ionomer or zinc phosphate agents were not significant.
Acid-etched Dicor restorations luted to gold preparation core structures exhibited significantly better intraoral survival than restorations luted to dentin. Acid-etched Dicor restorations survived better than nonacid-etched restorations when luted to dentin preparations. Acid-etched Dicor restorations luted with resin composite exhibited more favorable survivor functions than restorations luted with glass ionomer or zinc phosphate agents.
A retrospective 17-year, longitudinal study monitoring 66 patients with fixed partial denture and removable partial denture restorations revealed that perceptive splinting was beneficial and enhanced the longevity of the restoration. The study discussed the advantages and disadvantages of splinting, the survival rate of splints and splinted teeth, and the importance of oral hygiene and a periodic maintenance program.
The survival percentage for the transosteal implant is 80.9% +/- 0.04 and predictably satisfactory host site responses may be anticipated at the 100% level after the second successful year in situ. The benefits of the transosteal implant are its unsophisticated design with a straight uncomplicated cervix, a simple surgical technique, economy, immediate fixation and readiness for use, modesty of size, versatility (it may be used singly or in diverse multiples in association with teeth or other implants), ease of removal when indicated, and universality of application to a broad variety of anatomic and prosthetic situations.
Seventeen porcelain-fused-to-metal alloys, which represented a cross section of the various alloy types available, were evaluated for castability, opaque masking, and porcelain bond strength. The base metal alloys generally cast more completely than the noble alloys, with the presence of beryllium as an important factor for greater castability among the base metal alloys. Statistically significant differences were observed in the ability of an opaque porcelain to mask the different alloy substrates but no systematic effect of alloy type was observed. Porcelain bond testing revealed that nickel-chromium-beryllium alloys produced significantly better porcelain-metal bonds than nickel-chromium alloys without beryllium. In addition, it was found that palladium-copper alloys produced significantly better bonds with porcelain than palladium-cobalt alloys.
SEM studies indicate that the control alloy, Minigold, WLW, and Litecast metals presented similar results in relation to marginal fit when proper techniques are followed. Clinical evaluation based on the criteria of gingival irritation, patient sensitivity, and abrasion demonstrated no statistically significant differences between the casting alloys tested and the control. The control alloy had significantly fewer restorations with tarnish and corrosion than either WLW or Litecast. There was no significant difference between the control alloy and Minigold in terms of tarnish and corrosion.
Histologic evaluation of a single immediately loaded titanium provisional implant that was in function for 18 months revealed 81.3% bone-to-implant contact of the surface evaluated, whereas 9.6% of the implant surface evaluated was opposed by marrow and 9.1% by connective tissue. The bone appeared to be in active remodeling stage and in close contact with the implant surface.
Fabricating dentures for the patient with severe mandibular atrophy can be a challenge for both the dentist and patient. Subperiosteal implants with a mandibular overdenture may be a solution for the atrophic mandible.
The purpose of this retrospective study was to review the survival of mandibular subperiosteal implants placed at the University of Missouri Kansas City (UMKC) School of Dentistry Graduate Prosthodontics program between 1982 and 2000.
Forty subperiosteal implants were placed in atrophic mandibles of 40 patients (33 women, 7 men) between 1982 and 2000. The age range of the patients was 47 to 80 years of age at time of placement (mean=62 years). Each patient was reviewed clinically by an author (DJM). Manual depression and lifting of the framework were used to evaluate the stability of the implant. Additionally, the implants were observed for any movement. Each patient was questioned for pain or discomfort. Each patient was examined for observable inflammation and intraoral exposure of the framework and questioned as to whether the implant had satisfied the patient and met the patient's expectations.
Thirty-nine of the 40 original patients were recalled in 2000. One patient had died. Fourteen patients had implants for over 10 years, 12 patients had implants between 5 and 10 years, and 12 patients had implants for less than 5 years (mean time of implant service=8 years). Thirty-eight patients had the implant in place with no sign of inflammation or mobility, 1 patient with diabetes had inflammation around one of the struts. All patients were wearing their prostheses, and there was no sign of exposed implant framework for any patient. All patients reported a high level of satisfaction with the implant.
Within the limitations of this study, the mandibular implants placed at UMKC were still functioning, and all patients denied any discomfort or pain from the prostheses. Patients reported they were comfortable and able to function with the implant-supported prosthesis.