The International Journal of Prosthodontics, 03/2012

Purpose: The aim of this study was to quantify and compare the clinical performance of cast conical double crown-retained removable partial dentures (C-RPDs) and electroplated double crown-retained removable partial dentures (EP-RPDs). Materials and Methods: A total of 60 RPDs were placed in 54 patients. Participants were randomly assigned to two study groups (C-RPD and EP-RPD). Altogether, 217 abutment teeth were provided with double crowns. Patients were reexamined after 6, 12, 24, and 36 months. The main endpoints were the survival times of RPDs and abutment teeth; secondary endpoints included failure of the facing, loss of cementation of primary crowns, and postprosthetic endodontic treatment. Chi-square tests were used to evaluate group differences regarding characteristics of patients and RPDs. Survival differences were investigated using the log-rank test and Cox regression; secondary endpoints were assessed using logistic regression. Results: After 36 months, survival was 100% for C-RPDs and 93.3% for EP-RPDs. Cumulative survival for abutment teeth was 97.3% (C-RPDs) and 96.2% (EP-RPDs). Survival differences between the two study groups did not reach statistical significance. The survival of abutments depended on tooth vitality and position; for example, the hazard of tooth loss was 676% higher for nonvital teeth. No differences were found between study groups regarding facing failure, decementation of primary crowns, or postprosthetic endodontic treatment. Conclusions: Vitality and position are important to the survival of teeth supporting partial dentures. Longer follow-up and larger patient collectives are needed to evaluate possible differences between cast conical and electroplated telescopic double crown-retained partial dentures.

Clinical outcomes for frictional telescopic crowns supporting removable prostheses in patients with severely reduced dentitions with one to three remaining teeth per arch have been inadequately documented. Seventy-four patients with severely reduced dentitions received 82 telescopic removable partial dentures that were supported by 173 frictional telescopic crowns. The recorded individual telescopic abutment survival rate over a 60-month period was 80.6%. This observation was significantly influenced by sex and tooth vitality and mobility (Kaplan-Meier). The risk of loss of telescopic crowns was significantly influenced by sex, arch, vitality, and abutment tooth distribution (Cox regression). Telescopic removable partial dentures were proven to be a favorable treatment concept for severely reduced dentitions in the selected group of patients.

Purpose: The aim of this randomized controlled clinical trial was to compare the outcomes of zirconia crowns and fixed partial dentures (FPDs) supported by teeth or implants. Materials and Methods: Patients were recruited based on inclusion/exclusion criteria, and 59 eligible subjects were assigned randomly to treatment by one of four zirconia systems (Cercon, ZirkonZahn, Lava, and Katana). One hundred seven single-tooth and 160 three- to six-unit FPDs were fabricated on teeth and implants and cemented using composite resin cement. Californian Dental Association (CDA) quality evaluation, Plaque Index, and Gingival Index scores were recorded, and radiographic assessment of the restorations was performed using periapical and panoramic radiographs at baseline and annually up to 4 years. Results: Five failures (1.9%) were recorded. The 4-year Kaplan-Meier survival probabilities of FPDs were higher than those of single-tooth restorations (P = .046). The highest survival probability for crowns was observed for Katana and the lowest for Cercon (P .05). For FPDs, the survival probabilities of Lava restorations were similar to those of Cercon but lower than those of ZirkonZahn and Katana (P .05). The 4-year survival probabilities of implant- and tooth-supported crowns were comparable (P = .182). Regarding CDA ratings, the slight marginal discrepancy scores for the Cercon restorations were higher than for the other systems at 1 year (P .05). In FPDs, 94.5% of Katana FPDs had slight or gross color mismatch scores, and the difference between color and surface ratings among zirconia systems was significant (P .05). FPDs had better periodontal scores than crowns over the 4-year observation period (P .05). Conclusion: The 4-year interim results of this study suggest that zirconia systems used to fabricate FPDs have predictably high survival rates on teeth and implants and may exhibit differences, particularly in terms of mechanical failures, marginal adaptation, and color matching.

Purpose: The aim of this randomized clinical trial was to compare the effectiveness of microwave denture disinfection and nystatin in the treatment of well-controlled type 2 diabetic patients with denture stomatitis in terms of microbiologic and clinical outcomes. Materials and Methods: Diabetic patients wearing maxillary complete dentures with denture stomatitis (n = 40) were divided into two groups: NYS (patients treated with topical nystatin 4 times/day for 14 days) and MW (patients who had their dentures microwaved [650 W for 3 minutes] 3 times/week for 14 days). Mycologic samples were taken from the palates and dentures of the patients for quantification and identification of Candida, and standardized photographs of the palates were taken for clinical analysis. Evaluations were repeated at baseline, the end of treatment (day 14), and throughout follow-up (days 30, 60, and 90). Microbiologic data were evaluated by analysis of variance using a random effects statistical model, Tukey post hoc test, and chi-square test (α = .05). Clinical resuts were analyzed using Mann-Whitney and Fisher exact tests (α = .05). Results: Both treatments were considered successful in reducing the clinical signs of denture stomatitis and significantly reduced the values of colony-forming units/mL from the palates and dentures at days 14 and 30. In addition, 40% of treated patients were cured by the end of treatment. No significant differences in the microbiologic and clinical outcomes were revealed between the two groups (P > .05). C albicans was the most predominant species isolated (P .01), followed by C tropicalis and C glabrata. Conclusion: Denture microwave disinfection was as effective as nystatin for the treatment of diabetic patients with denture stomatitis.

Purpose: Insight into the bone volume and position of natural teeth is essential when placing implants to retain nasal prostheses. This paper describes a series of three cases in which a new method was applied for implant placement in the nasal floor of dentate patients using digital planning techniques. Materials and Methods: With the aid of computer software, digital planning of implants in the nasal floor based on cone beam computed tomography was performed. Next, surgical guides for implant placement were digitally designed and fabricated using rapid prototyping. Results: In all three patients, implants could be placed and nasal prostheses could be manufactured as planned. All anterior teeth remained vital. Analysis of planning and post-implant placement cone beam computed tomography scans revealed high accuracy of implant placement. Conclusion: The applied method allows for reliable implant placement in close proximity to the preoperatively planned implant position.

Purpose: The aim of this research was to assess survival and complication rates of tooth- and implant-supported fixed dental prostheses (FDPs) and single crowns (SCs) after 5 years of function in a specific patient population group who underwent comprehensive prosthetic treatment. Materials and Methods: This retrospective study included a convenience sample of 52 patients who met specific inclusion and exclusion criteria and were treated during two specific courses as part of the undergraduate curriculum. The patients' prosthodontic treatment comprised 296 tooth-supported and 37 implant-supported SCs together with 76 tooth-supported and 15 implant-supported FDPs. Pre- and posttreatment clinical examinations included screening for biologic and technical complications, probing pocket depth, bleeding on probing (BoP), and plaque control record (PCR) as well as intraoral radiographs. Information was obtained from the patients about dental hygiene and dental visits, treated complications, and patient satisfaction during the observation period. Descriptive statistics were employed. Results: Forty-five patients were followed for a mean observation period of 5.26 ± 0.47 years. The survival rates were 99.0% for tooth-supported SCs, 98.7% for tooth-supported FDPs, and 100% for implant-supported FDPs and SCs. Loss of vitality was observed in 2.9% of all abutment teeth deemed to be vital initially. Endodontic complications occurred in 5% and root fracture in 2.5% of nonvital abutment teeth. Caries was found in 0.4% of abutments. No framework or implant fractures were observed, but fracture of the veneering ceramic affected 3.8% of FDPs. The mean BoP was 21.5% ± 9.9%, and the mean PCR was 22.8% ± 16.5%. A high satisfaction rating was provided by 82.2% of patients. Conclusions: High survival and relatively few complication rates were observed for all prescribed FDPs over the observation period.

The aim of this research was to evaluate internal and marginal adaptation of lithium disilicate partial crowns fabricated using IPS e.max Press and IPS e.max CAD systems. Forty maxillary first molars were divided into two groups. The margins were located above the cementoenamel junction mesially and below it distally. The adaptation of the restoration was evaluated by means of the silicone replica technique. The lowest marginal discrepancy was measured between the preparation margin on the enamel and the IPS e.max Press specimens; the highest discrepancy was observed on the occlusal surface of the IPS e.max CAD specimens. Both systems tested demonstrated acceptable marginal discrepancies in vitro.

Purpose: This study investigated the clinical performance of resin-bonded fixed partial dentures (RBFPDs) using minimally invasive, nonretentive abutment tooth preparation. Materials and Methods: Forty-four patients received 56 porcelain-fused-to-metal RBFPDs (52 three-unit RBFPDs, 4 four-unit RBFPDs). All RBFPDs were inserted between 1995 and 2010 according to a standardized protocol. Thirty-eight RBFPDs replaced anterior teeth in the maxilla, 18 RBFPDs replaced anterior teeth in the mandible, and 3 RBFPDs replaced premolars (1 maxillary, 2 mandibular). At annual recall appointments, RBFPDs were carefully inspected for technical and biologic failures or complications (eg, debonding, abutment tooth caries). Results: The mean observation period was 76 months, with a minimum of 4 months and a maximum of 198 months. Five RBFPDs debonded. Further complications comprised one instance of porcelain chipping and one caries lesion underneath a loose retainer. One patient was dissatisfied with the esthetic appearance of her RBFPD. The cumulative survival rate with the event "debonding" dropped to 90% after 23 months and then remained constant. Survival rate with the event "any restoration complication" dropped to 84% after 77 months and then remained constant. Conclusions: With regard to the high patient satisfaction and relatively low incidence of failures and complications, the clinical performance of nonretentive RBFPDs can be considered satisfactory. Hence, within the limitations of this study, the data justify nonretentive RBFPDs as long-term provisional restorations.

Purpose: The aims of this research were to describe the process leading to desire for implant treatment, describe how patients missing teeth gained information about implant treatment, identify gatekeeping factors for implant treatment, and note experiences in changes in oral health-related quality of life. Materials and Methods: The constant comparative method for a grounded theory was used in collecting and analyzing data. Ten informants participated in the study, all of whom were treated with implant-supported fixed dentures during the past year. Results: The emerging core category was that participants experienced a journey from social stigma to exhilaration. This process ended in the perspective that the participants' new lives with dental implants were very good and meant an end to their social stigma, but gatekeeping factors before treatment, such as cost and dental anxiety, were noted. The dentist's opinion and suggestions were the most decisive part of the decision-making process, and trust in the dentist and dental team was crucial in the decision to undergo treatment and in the overall treatment experience. Great improvement in oral health-related quality of life was noted. Conclusion: This qualitative study gives as the core category and main finding the importance of patients' trust and confidence in the dentist and his/her staff in the process of transforming desire for dental implant treatment into demand and also in making it more likely for patients to be satisfied with treatment regardless of complications.

Purpose: The aim of this study was to prospectively evaluate clinical and radiographic outcomes of ultrashort implants (4-mm diameter, 6-mm length) supporting fixed partial dentures in severely atrophic posterior mandibles. Materials and Methods: Twenty-five patients with posterior edentulous mandibular spans and 7- to 8-mm residual bone heights above the mandibular canal were enrolled. In total, 61 submerged implants were placed and loaded 5 to 6 months later. Patients were followed for 2 years after prosthesis connection with clinical, radiographic, and resonance frequency analysis (RFA) examinations. Results: Two implants failed in one patient before loading; all other implants showed favorable clinical and radiographic findings throughout the observation period (2-year survival and success rate: 96.8%). Postoperative pain and swelling were negligible. Mean changes in marginal bone levels were stable (0.40 ± 0.23, 0.51 ± 0.38, and 0.60 ± 0.13 mm after 6 months and 1 and 2 years, respectively) and were unaffected by measured crown-to-implant ratios (range: 1.31 to 3.12). Mean RFA values increased significantly from implant placement (67.35 ± 6.67) to 2 years (72.91 ± 5.07, P .0001). Prosthetic complications included two prosthesis decementations, three ceramic veneer chippings, and one prosthesis screw loosening. Conclusion: Within the limitations of the short follow-up period, the use of 6-mm-long implants was a predictable treatment method for patients with atrophic posterior mandibles and increased crown-to-implant ratios.

Permanent facial paralysis can be devastating for a patient. Modern society's emphasis on appearance and physical beauty contributes to this problem and often leads to isolation of patients embarrassed by their appearance. Lagophthalmos with ocular exposure, loss of oral competence with resultant drooling, alar collapse with nasal airway obstruction, and difficulties with mastication and speech production are all potential consequences of facial paralysis. Affected patients are confronted with both a cosmetic defect and the functional deficits associated with loss of facial nerve function. In this case history report, a modified maxillary complete denture permitted a patient with Bell palsy to carry on daily activities with minimal facial distortion, pain, speech difficulty, and associated emotional trauma.

Purpose: Clinical studies have revealed a high rate of fracture for porcelain-veneered zirconia-based restorations that varies between 6% and 15% over a 3- to 5-year period. These are high values compared to the 4% fracture rate shown by conventional metal-ceramic restorations over 10 years. To date, little in vitro research has been carried out on the fracture resistance of the new generation of ceramic crowns. The aims of this study were to develop preliminary research on the mechanical failure behavior of three types of porcelain-veneered crowns with zirconia cores when subjected to static compressive loading and to analyze fracture characteristics using scanning electron microscopy (SEM). Materials and Methods: Eighty individual full-coverage crowns were studied: 60 crowns with a zirconia core and 20 with a metal core (control). Results: Values obtained in compressive testing were as follows: ZirPress: 1,818.01 N, ZirCAD: 1,773.92 N, Lava: 2,210.95 N, and metal-ceramic (control): 2,310.49 N. SEM analysis revealed that 71.66% of zirconia-based restoration mechanical failures were cohesive, while 100% of mechanical failures for metal-ceramic restorations were adhesive. Conclusions: The mechanical behavior of the porcelain veneering on a zirconia core is more fragile than that on metal-ceramic crowns, and when load forces exerted on these restorations lead to mechanical failure, this will occur in the interior of the porcelain veneering.