Modified United States Public Health Research Articles

A Screwless and Cementless Technique for the Restoration of Single‐tooth Implants: A Retrospective Cohort Study

The Integrated Abutment Crown (IAC) is a technique for the fabrication of single-tooth implant-supported crowns where the abutment and the crown are one unit. The abutment-crown complex is connected to the implant with a locking taper. This technique does not use cement to retain the crown or screws to retain the abutment. The purpose of this study was to evaluate the clinical outcome of screwless, cementless single implant-supported crowns (IACs) placed in a general dental practice. A retrospective cohort study was conducted between July 2001 and August 2003. Patients were recalled between January and March 2004. The restorations were evaluated following the modified United States Public Health Service (USPHS) criteria. Several other variables, such as anatomic form, occlusion, soft tissue health, and reconstructive procedures, were also recorded. Descriptive statistics, univariate and multivariate marginal Cox Proportional Hazards Regression models, adjusted for multiple implants in the same patient, were used. During the chart review, 108 patients were identified. A cohort of 59 patients with a total of 151 IACs met the inclusion criteria. The Kaplan-Meier survival rate for IACs was 98.7%. Two IACs were removed, one due to implant failure; the other became loose several times and was replaced with a splinted restoration. Excellent marginal adaptation was observed with no clinically discernible interface between the veneer material and the abutment. Nine maxillary anterior IACs loosened on five patients; eight of them were reinserted and continued in function without further problems for the remainder of the study. An IAC located between a tooth and an implant was 2.65 times more likely to have postinsertion complications (p= 0.05). An IAC with incorrect anatomic form (overcontoured) was 3.26 times more likely to have postinsertion complications (p= 0.01). Maxillary anterior IACs adjacent to one tooth and one implant were 3.9 times more likely to come loose (p= 0.05). The clinical outcome of this screwless and cementless system for single implant restorations compares favorably with the experience of screw- and cement-retained single implant restorations within the observation period.

Two‐year follow‐up of fractured anterior teeth restored with direct composite resin: report of three cases

Thirty-five (case 1), 15 (case 2) and 22 (case 3)-year-old female patients presented to Yeditepe University Dental Faculty Clinic because of esthetic reasons. Fractures of maxillar central incisors including enamel and dentin were diagnosed. Beveling with diamond bur was performed in all four cases. Dentin was cleaned with tungsten carbid bur. The teeth were etched with 37% phosphoric acid, restored with an adhesive system and microhybrid composite. Finishing and polishing procedures were performed by discs (Sof-Lex) and burs. Restorations were found successful according to modified United States Public Health Service (USPHS) criteria after 2 years in terms of retention, color match, marginal discoloration, secondary caries, marginal adaptation, and surface texture.

One Year Clinical Evaluation of Two Different Types of Composite Resins in Posterior Teeth

The aim of this study was to assess the clinical performance of two adhesive restorative systems (Single Bond/Filtek P-60 and Single Bond/Filtek Z-250) in posterior teeth using a modified United States Public Health Service (USPHS) system. A total of 70 restorations were placed in molars and premolars in 30 patients (14 females and 16 males; 18-40 years) by one operator. All restorations were directly evaluated by two examiners at baseline, six months, and 12 months using the following modified USPHS rating criteria: marginal integrity, marginal discoloration, surface texture, contour, postoperative sensitivity, and recurrent caries. At six and 12 months all restorations were available for evaluation of marginal discoloration, surface texture, contour, postoperative sensitivity, and recurrent caries that remained with 100% Alpha-ratings at recalls for both restorative systems. Marginal integrity for P-60 was scored as 94.3% and 91.4% Alpha at six and 12 months, respectively, and rates for Z-250 were 100% and 97.1% Alpha at six and 12 months, respectively. Statistical analysis was completed with Fisher's exact and McNemar Chi-square tests at a significance level of 5% (P<0.05). All restorations were clinically satisfactory and no significant differences were found among them. Posterior resin composite restorations placed under appropriate conditions provide a satisfactory clinical performance.

Long-term clinical results of chairside Cerec CAD/CAM inlays and onlays: a case series.

The objective of this follow-up study was to examine the performance of Cerec inlays and onlays, all of which were placed by the same clinician, in terms of clinical quality over a functional period of 15 years. Of 200 Cerec inlays and onlays placed consecutively in a private practice by one of the authors (TO) between 1989 and early 1991, 187 were closely monitored over a period of 15 years. All ceramic inlays and onlays had been placed chairside using the Cerec 1 method and had been luted with a bonding composite. Up to 17 years after their placement, a follow-up assessment was conducted, and the restorations were classified using modified United States Public Health Service criteria. According to Kaplan-Meier analysis, the success rate of Cerec inlays and onlays was 88.7% after 17 years. A total of 21 failures (11%) were found in 17 patients. Of these failures, 76% were attributed to ceramic fractures (62%) or tooth fractures (14%). The reasons for the remaining failures were caries (19%) and endodontic problems (5%). Restorations of premolars presented a lower failure risk than those of molars. The survival rate probability of 88.7% after up to 17 years of clinical service for Cerec computer-aided design/computer-assisted machining restorations made of Vita Mk I feldspathic ceramic is regarded as a very respectable clinical outcome.

Clinical evaluation of two packable posterior composites: 2-year follow-up

The clinical performance of two packable posterior composites, Alert (A)-Jeneric/Pentron and SureFil (S)-Dentsply, was evaluated in 33 patients. Each patient received one A and one S restoration, resulting in a total of 66 restorations. The restorations were placed by one operator according to the manufacturer's specifications and were finished and polished after 1 week. Photographs were taken at baseline and after 2 years. Two independent evaluators conducted the clinical evaluation by using modified United States Public Health Service criteria. After 2 years, 60 restorations (30 A and 30 S), 27 class I (16 A and 11 S) and 33 class II (14 A and 19 S) were evaluated in 30 patients. Criterion A for recurrent caries, vitality, and retention was applicable to all 60 restorations. Criterion B was distributed among 40 restorations as follows: surface texture (15 A; 2 S), color (5 A; 6 S), postoperative sensitivity (1 S), marginal discoloration (8 A), marginal adaptation (3 A), and wear resistance (2 A). Data were analyzed using the Exact Fisher and McNemar tests. After 2 years, S showed a significantly better performance than A with respect to surface texture and marginal discoloration. The clinical performance of both materials was considered acceptable over the 2-year period. Further evaluations are necessary for a more in-depth analysis.

Marginal Adaptation of Cerec 3 CAD/CAM Composite Crowns Using Two Different Finish Line Preparation Designs

The purpose of this study was to compare marginal discrepancies of Cerec 3 CAD/CAM composite crowns, fabricated on human prepared teeth with two different finish line designs, chamfer and shoulder. Sixteen human molar teeth were used to prepare full crowns. Eight teeth were prepared with a 1-mm-wide chamfer finish line and the other eight with a 1.2- to 1.5-mm circumferential shoulder. Cerec 3 crowns were fabricated from optical impressions using Paradigm MZ100 composite polymer. Marginal adaptation was evaluated in two ways: (1) using modified United States Public Health Service (USPHS) criteria to evaluate eight preselected sites on each crown margin, and (2) using scanning electron microscopy (SEM) to measure marginal gaps on all four axial walls with 15 measurements on each wall (60 measurements per crown). An evaluation of the number of acceptable crowns, determined by having all measured sites per tooth with margin gap size less than 100 microm, as a function of finish line design was also conducted. In both chamfer and shoulder groups, there were only two crowns (out of eight) with clinically acceptable ratings for all eight measurement sites according to USPHS criteria. Fisher's chi-square analysis showed that there was no statistically significant difference in marginal adaptability as a function of finish line design ( p>0.05). With SEM imaging, overall mean marginal gaps for the chamfer group were 65.9+/-38.7 microm (range 35.0 to 130.0 microm), and for the shoulder group were 46.0+/-9.2 microm (range 26.3 to 55.6 microm); this difference was not found to be statistically significant ( p>0.05). While crown assessment based on mean marginal discrepancy measurements indicated that both the chamfer and shoulder groups were considered clinically acceptable (<100 microm); crown acceptability based on all measurement sites being less than 100 mum indicated that in the chamfer and shoulder groups there were four and three acceptable crowns out of eight, respectively. The Fisher's chi-square test indicated no statistically significant difference between the groups ( p>0.05). An agreement rate of 81.2% was calculated between the two evaluation methods, modified USPHS criteria and SEM measurements. Based on mean marginal discrepancy measurements, the typical marginal assessment technique, Cerec 3 Paradigm MZ100 crown restorations appear to have acceptable marginal adaptability (mean discrepancies <100 microm). Thus, the evidence from this investigation would suggest that the finish line preparation design had no effect on marginal adaptation for Cerec 3 composite crowns.

Two-year clinical performance of cast gold vs ceramic partial crowns

Cast gold partial crowns (CGPC) are an accepted means of restoring posterior teeth with extended lesions. However, for esthetic reasons, CGPC are being increasingly substituted with partial ceramic crowns (PCC). The aim of the present prospective split-mouth study was to compare the clinical performance of PCC and CGPC. There were 29 patients (male 12, female 17) who participated in the investigation for a total of 58 restorations. In each patient, one CGPC (Degulor C) and one PCC (Vita MarkII/Cerec III) were placed. CGPC were inserted using conventional zinc-phosphate cement (Harvard); PCC were adhesively luted to the cavities (Variolink II/Excite). The restorations were clinically rated using modified United States Public Health Service (USPHS) criteria at baseline and 1 and 2 years after placement. The median patient age was 38 years (range 25-54). There were 29 of the CGPC and 14 PCC placed in molars, while 15 PCC were placed in premolars. All patients were available for the 1- and the 2-year recall. One PCC (1.7%) failed and had to be replaced after 2 years in situ. The rest of the restorations were functional without need of replacement. The evaluation using USPHS criteria revealed no statistically significant differences between CGPC and PCC with the exception of anatomic form: PCC showed occlusal chipping in two cases without need of replacement. From these data, it can be concluded that PCC may provide an esthetic and tissue-conservative alternative to CGPC. However, long-term studies comparing the clinical performance and longevity of cast gold and ceramic partial crowns for posterior teeth are desirable.

Clinical Evaluation of Posterior Composite Restorations in Endodontically Treated Teeth

The purpose of this study was to evaluate the two year clinical performance of posterior composite restorations in endodontically treated premolars and molars using a hybrid composite (Filtek Z-250, 3M ESPE) and a total etch bonding system (Single Bond, 3M ESPE). Thirty-nine class II restorations in endodontically treated premolars (n=11) and molars (n=28) of 27 patients (14 female, 13 male, mean age 36.51) in 16 maxillar and 23 mandibular teeth were placed by one operator. Restorations were evaluated by two experienced investigators at baseline, 12 months, and 24 months according to the modified United States Public Health Service (USPHS) criteria that included retention, color match, marginal discoloration, secondary caries, anatomic form, marginal adaptation, and surface texture. All restorations were able to be evaluated at baseline, 12 months, and 24 months. Paired samples t-test showed only marginal discoloration showed a statistically significant difference (p<0.05) at the end of 24 months, and no other significant differences were observed for the other variables examined over the duration of the study. None of the restored teeth showed periapical pathology at the end of 24 months. At two years, limited deterioration in marginal discoloration was detected. The clinical performance of posterior composite restorations in endodontically treated teeth using Filtek Z250 was found clinically acceptable after two years.

Inlay‐fixed partial dentures adhesively retained and reinforced by glass fibers: clinical and scanning electron microscopy analysis after five years

Fifty-three posterior glass fibre-reinforced composite inlay-fixed partial dentures (IFPDs) in 36 patients were followed for 5 yr. For statistical analysis, one IFPD per patient was randomly selected. The survival rate and influence of discrete predictors (gender, location) and continuous variables (age, abutment surfaces) were determined. Clinical observations were recorded by using modified United States Public Health System (USPHS) criteria. Replicas of 17 randomly selected abutments were analysed by scanning electron microscopy (SEM) for marginal adaptation and the results were compared by using a repeated-measures analysis of variance (anova). The main reason for failure was veneering material delamination from the framework. The cumulative survival rate after 5 yr was 73% (95% confidence interval: 57-89%) for not delaminating and 96% (95% confidence interval: 88-100%) for not debonding. No significant influence of the tested predictors was found. Significant changes between baseline USPHS criteria and counterparts recorded at recall were fractures of the veneering material (chipping), wear, surface texture, and staining. Significant margin changes were only found between baseline and 1 yr. Thereafter, marginal adaptation remained stable. After 5 yr, 90% of the margins were termed as perfect. It was concluded that hard-tissue saving IFPDs with the current design maintained acceptable retention and marginal integrity. Future studies should aim at reducing delaminations by searching for improved framework designs and materials.

122 Safe dental amalgam removal in patients with immunotoxic reactions to mercury

Ultrathin bonded posterior occlusal veneers represent a conservative alternative to traditional onlays and complete coverage crowns for the treatment of erosive dental wear. Data regarding the clinical performance of ceramic and composite resin ultrathin occlusal veneers are lacking.The purpose of this prospective randomized clinical trial was to evaluate the influence of computer-aided design and computer-aided manufacturing (CAD-CAM) restorative material (ceramic versus composite resin) on the clinical performance of ultrathin occlusal veneers bonded to worn posterior teeth.Eleven participants (mean age, 30.4 years) had their posterior teeth restored with 24 ceramic (e.max CAD) and 36 composite resin (Lava Ultimate) ultrathin occlusal veneers. The material type was assigned randomly. The tooth preparations were trial restoration driven and included immediate dentin sealing (OptiBond FL). The intaglio surfaces of the ceramic restorations were etched with hydrofluoric acid and silanated, and the composite resins were airborne-particle abraded and silanated. The tooth preparations were airborne-particle abraded and etched with phosphoric acid before restoration insertion. All restorations were adhesively luted with preheated composite resin (Filtek Z100). The participants were evaluated according to the modified United States Public Health Service (USPHS) criteria at baseline and then each year for up to 3 years. Survival rates were estimated with time to failure (primary outcome of interest) as the endpoint (scores 4 or 5).No restorations were lost. Five partial failures, in the form of chipping (all scored 4), were observed in the composite resin group (Lava Ultimate). The Kaplan-Meier survival rates were 100% for ceramic and 84.7% (SE 0.065%) for composite resin. Differences between the 2 groups were not statistically significant (P=.124). In the surviving restorations, significant difference (P=.003) was found for surface roughness as restorations in the composite resin group experienced some surface degradation.The findings of this medium-term clinical trial suggest that ceramic (e.max CAD) and composite resin (Lava Ultimate) CAD-CAM ultrathin occlusal veneers presented statistically comparable performance regardless of the minor partial failures (restorable chipping) observed in the composite resin group. Higher surface degradation was observed in the composite resin group.

The survival and clinical performance of resin-based composite restorations used to treat localised anterior tooth wear.

To examine the clinical performance of resin-based composite restorations placed at an increased vertical dimension when used to manage localised anterior tooth wear. A retrospective analysis of cases treated at a single centre. UK Hospital setting in the year 2000. Two hundred and twenty five restorations placed in 31 subjects were included. Assessment was made following examination of study casts and projected slides. Modified United States Public Health Services criteria were used and data analysed using the software Statistical Programme for Social Sciences (SPSS). Survival analysis was carried out at two levels, major failure only and all types of failure. Kaplan-Meier survival plots were produced against different variables and modes of failure were also noted. Major failure requiring replacement of the restoration was uncommon within the first five years. Minor failure requiring repair or refinishing presented mainly as wear, marginal discolouration or marginal fracture. Median survival was 4 years 9 months when all types of failure were considered. The restorations have good appearance and are well tolerated. Placement of resin-based composite restorations at an increased vertical dimension to treat localised anterior tooth wear, has good short to medium term survival. The technique is conservative and relatively easy to maintain.

Performance of resin-based composite restorations to manage anterior tooth wear

Objectives To examine the clinical performance of resin-based composite restorations placed at an increased vertical dimension when used to manage localised anterior tooth wear. Design A retrospective analysis of cases treated at a single centre. Setting UK Hospital setting in year 2000. Subjects and Methods Two hundred and twenty five restorations placed in 31 subjects were included. Assessment was made following examination of study casts and projected slides. Modified United States Public Health Services criteria were used and data analysed using the software Statistical Programme for Social Sciences (SPSS). Survival analysis was carried out at two levels, major failure only and all types of failure. Kaplan-Meier survival plots were produced against different variables and modes of failure were also noted. Results Major failure requiring replacement of the restoration was uncommon within the first five years. Minor failure requiring repair or refinishing presented mainly as wear, marginal discolouration or marginal fracture. Median survival was 4 years 9 months when all types of failure were considered. The restorations have good appearance and are well tolerated. Conclusion Placement of resin-based composite restorations at an increased vertical dimension to treat localised anterior tooth wear, has good short to medium term survival. The technique is conservative and relatively easy to maintain.

Clinical evaluation of an urethane tetramethacrylate‐based composite material as a prosthetic veneering agent

The purpose of the current study was to evaluate the clinical performance of a hybrid composite material used as a prosthetic veneering agent after servicing for more than 4 years. A photo‐curable composite material (Cesead®) was selected as the veneering agent. Composite resin veneered restorations made with the composite and a noble metal alloy were inserted into 110 teeth of 40 patients. Modified United States Public Health Service (USPHS) criteria were used for direct evaluation of colour matching ability, veneer–metal interfacial staining, veneer surface texture, staining of the metal casting, and wear of the veneer–metal interface. After an average observation period of 5 years and 3 months, the rate of restorations considered to be clinically ideal (Alfa) was 75·5% for colour match, 93·6% for veneer–metal interfacial staining, 82·7% for veneer surface texture, 97·3% for staining of the metal casting, and 95·5% for wear. The restorations judged as clinically unacceptable (Charlie) consisted of only one case for colour match and three cases for veneer surface texture. Although the Alfa rate decreased with increasing length of service, the Cesead® composite is considered to be a clinically reliable material as a prosthetic veneering agent.

Compomer versus glass ionomer restorations: which material performs better in primary molars?

Objectives To undertake a clinical trial comparing the efficiency of a compomer restoration with a glass ionomer restoration in the management of caries in primary molar teeth. Design Subjects were admitted to the trial if they required at least one pair of restorations in primary molar teeth. Setting Department of Child Dental Health, Newcastle Dental Hospital and School. Subject Twenty nine children, aged 4–9 years, had 56 pairs of restorations placed between January 1995 and November 1997. Method The durability of the restorations was assessed during a 42-month follow-up period using modified United States Public Health Service criteria. Survival analysis and the McNemar paired test were used to compare the performance of the two restorative materials. Results The compomer restorations had a higher mean survival time (42 months, SE 1.40) compared with 37 months (SE 1.90) for the glass ionomer restorations and this was significant at the 5% level. The compomer also performed significantly better in terms of anatomical form, marginal integrity, cavo surface discoloration and maintenance of interproximal contact. Conclusions The present trial demonstrated that Dyract compomer performed significantly better than Chemfil Superior a glass ionomer cement for all modified United States Public Health Service criteria over a period of 42 months.

Long-term survival estimates of cast gold inlays and onlays with their analysis of failures.

The aim of the present study was to assess the clinical behaviour of cast gold restorations with respect to define a gold control against current and future ceramic and composite restorations. The study sample included 50 patients with 303 cast gold restorations. All restorations were cemented with a non-adhesive technique. A total of 303 restorations were evaluated clinically and radiographically using modified United States Public Health Service criteria. Restorations recorded as having an A- or a B-rating were defined as successful. Of the 303 restorations, 42 were judged as failures, which resulted in a failure rate of 13.8% for a mean observation time (+/- s.d.) of 18.7 ( +/- 9.5) years. The estimated Kaplan-Meier survival rates (s.e.) were 96.1% (+/- 1.1%) at 10 years, 87.0% (+/- 2.2%) at 20 years and 73.5% (+/- 5.4%) at 30 years. In total, biological reasons were counted 25 times in comparison to 17 technical reasons for those 42 failed cast gold restorations, with 17 secondary caries (40%) as the most common biological reason and with 13 retention losses (31%) as the most common technical reason. The endodontically treated tooth was exclusively identified as a risk factor. The restoration type (inlay versus onlay) did not influence the survival rate.

Follow-up evaluation of a series of dentin-bonded ceramic restorations.

The results of a retrospective evaluation of 60 dentin-bonded full-coverage restorations with an average time in service of 2.4 years previously have been reported. The purpose of this study was to evaluate the crowns after a further 2 years in service. The 23 patients in the initial study whose restorations were found to be intact in June 1996 were contacted by mail and invited to present for review in October 1998. The restorations of 20 respondents were assessed by two examiners using modified United States Public Health Service criteria. The patients had received a total of 53 restorations (mean age of restorations, 4.4 years; range, 5.5-3 yr). At the time of examination, 48 restorations were found to be intact. No secondary caries was detected in these restorations, and optimal scores for gingival health, anatomic form, and marginal discoloration were recorded for 39, 47, and 33 crowns, respectively. Color match was assessed as being very good in 43 of the 48 restorations assessed. The reasons for replacement of the failed restorations were gingival recession (n = 1), restoration fracture (n = 1), core fracture (n = 1), and unknown (n = 2). Each patient's perception of his or her restorations was recorded by means of a questionnaire, with the responses indicating that all but two patients were satisfied. Only one patient had experienced any discomfort.

Seventeen‐Year Clinical Study of Ultraviolet‐Cured Posterior Composite Class I and II Restorations

To compare the clinical performance of four commercial ultraviolet light-cured composite materials, and to evaluate curing-system effects on long-term wear resistance of Class I and II restorations. Approximately 32 samples of each of four different ultraviolet light-cured composites (n = 130) were inserted into conventional Class I and II cavity preparations by two clinicians. Cavosurface margins of the preparations were not beveled. Enamel walls of the preparation were etched, and the respective bonding agent was applied. Each restoration was evaluated by two clinicians at 5, 10, and 17 years. Direct evaluations were performed using modified United States Public Health Service (USPHS) criteria. Indirect evaluations were performed using the Leinfelder cast evaluation method. After 17 years, 65% of the restorations were recalled and pooled direct evaluations were conducted for color matching (94% alfa), marginal discoloration (100% alfa), marginal integrity (100% alfa), secondary caries (92% alfa), surface texture (72% alfa), and anatomic form (22% alfa). Mean occlusal wear from indirect evaluations at 5, 10, and 17 years was 197 +/- 85 microns, 235 +/- 72 microns, and 264 +/- 80 microns, respectively. For direct and indirect evaluations there were significant differences (p < or = .05) between the baseline and 5-year recall evaluations. This study demonstrated that the mean pooled occlusal wear of four ultraviolet light-cured posterior composites at 17 years was 264 microns (approximately 0.25 mm), and that most wear (75%) occurred in the first 5 years. Of all recalled restorations, 76% were judged clinically acceptable at 17 years, and 22% of those exhibited no clinically detectable wear.

One-year clinical evaluation of composite and ceramic inlays in posterior teeth

Statement of problem. There are only a few studies available that deal with the clinical behavior of composite and ceramic inlay systems as potential substitutes for amalgam restorations. Purpose. This prospective clinical trial evaluated composite and ceramic inlay systems for clinical acceptability as restorative materials in single or multisurface cavities of posterior teeth and provided 1-year results. Material and methods. Forty-seven composite inlays (Tetric, Blend-a-lux, Pertac) and 24 heat-pressed ceramic inlays (IPS Empress) were placed in 45 patients by 7 student operators under the supervision of an experienced dentist. The first clinical evaluation was performed 11 to 13 months after placement of the restorations and used modified United States Public Health Services criteria. Results. Satisfactory results over this period were found, as 100% of ceramic inlays and 94% of composite inlays were assessed to be clinically excellent and acceptable. Only 3 composite inlay restorations were scored delta (unacceptable). Two inlays exhibited secondary caries and 1 demonstrated loss of pulp vitality. For the criteria “anatomic form of the surface” and “marginal integrity,” ceramic inlays were significantly better than composite inlays. Conclusion. Posterior tooth-colored inlays provided acceptable and excellent clinical service, even if they are placed by relatively inexperienced student operators. (J Prosthet Dent 1998;80:410-6.)

Short‐Term Results of IPS‐Empress Inlays and Onlays

A leucite-reinforced, glass-ceramic material was recently introduced for clinical use. In this clinical trial, IPS-Empress inlays and onlays were evaluated using the modified United States Public Health Service (USPHS) criteria. The teeth of 36 patients were restored with 105 posterior inlays and 25 onlays, fabricated by an indirect technique. After etching the restorations with hydrofluoric acid, they were silanized and luted using composite cements. The restorations were evaluated visually, clinically with a mirror and probe, and by bitewing radiographs and clinical photographs, using modified USPHS criteria. Restorations having neither charlie nor delta criteria were defined as successful, and their survival rate was calculated according to Kaplan-Meier analysis. The mean observation period for the 130 restorations was 23.4 +/- 6.1 months. After 2 years, 127 restorations were successful with an estimated survival rate of 97.5%. Three restorations failed because of fractures. The esthetic results were excellent. The initial clinical results of this esthetic restorative material are encouraging. However, because of fatigue phenomena for all ceramic materials, a longer observation period is needed to provide a definitive prognosis of the long-term clinical behavior.

A 3-year clinical evaluation of a porcelain inlay system

Objectives: The porcelain inlay technique was described over a century ago, and, although not yet used as a routine restorative procedure, may prove to provide restorations of unsurpassed functional and aesthetic qualities in certain situations. The aim of this study was to investigate the handling properties and clinicalcharacteristics of a porcelain inlay system, to highlight any advantages and disadvantages of the restorations under investigation, and to indicate further studies as considered appropriate. Methods: Fifty moderate to large-sized Class 1 and Class II restorations of a porcelain inlay system were investigated in premolar and permanent molar teeth of 27 adult patients over a 3-year period using modified United States Public Health codes and criteria. Selected restorations were evaluated indirectly by scanning electron microscopic analysis. Results: There was a high early rate of bulk fracture. By 6 months post-placement there had been a limited deterioration in marginal integrity associated with 20% of the remaining restorations, but this trend was not seen to continue. Patient acceptance was very favourable. Conclusions: It was concluded that the system under investigation afforded a technique-sensitive method of producing tooth-coloured restorations. Proposals for further work include investigations of the fitting accuracy of indirect tooth-coloured restorations, cavity design modifications and the use of alternative bases and luting agents.