The International Journal of Prosthodontics, 04/2008

Purpose: To identify and measure distortions inherent in the casting process of a Class III mandibular cobalt-chromium (Co-Cr) framework to illustrate the problems faced by the laboratory technician and the clinician and to measure the changes that occur during the correction of the fit discrepancy using laser welding. Materials and Methods: Five identical castings of a Co-Cr alloy partial denture casting were made and measured between 3 widely separated points using the x, y, and z adjustments of a Nikon Measurescope. The same measurements were made after each of the following clinical and laboratory procedures: sprue removal, sectioning of the casting into 3 parts through the posterior meshwork, fitting the segments to the master cast, picking up the segments using resin, and laser welding of the 3 segments. Results: Measurements of all 5 castings showed a cross-arch decrease after sprue removal, an increase after fitting the segments to the master cast, and a slight decrease after resin pickup and laser welding. Conclusions: Within the limitations of this study, the findings suggest that precise tooth-frame relations can be established by resin pickup and laser welding of segments of Co-Cr removable partial denture frameworks.

Purpose: The relationship between sleep bruxism (SB) and temporomandibular disorders (TMD) is unclear. This study aimed to estimate SB prevalence in an adolescent population and to investigate the relationship between SB frequency and prevalence of TMD signs/symptoms. Materials and Methods: First-year students at a high school in Okayama, Japan, were recruited in 2005, with 195 subjects responding. The SB detection device was a miniature disposable device (BiteStrip, SLP) that indicated the total SB events per night on a 4-grade score. The subjects were divided into severe and nonsevere SB groups with SB frequency cutoffs. The subjects were examined for temporomandibular joint (TMJ) noise during mouth opening/closing, tenderness of the masticatory/cervical muscles, and range of TMJ condylar movement. The presence/absence of headache and shoulder stiffness was also determined by the interview. The odds ratio (OR) and confidence interval (CI) were calculated to test the relationship between SB frequency, gender difference, and presence of the TMD signs/symptoms by multiple regression analysis. Results: Severe SB (more than 125 events per night) was significantly related to the presence of TMJ clicking (OR: 3.74, CI: 1.22-11.49, P = .02), while gender (male) was not related to the presence of TMJ clicking. Severe SB was not related to headache, though gender (male) was significantly related to headache (OR: 2.52, CI: 1.04-6.11, P = .04) in these subjects. Conclusion: These results suggest that the presence of TMJ clicking was closely related to severe SB in an adolescent population.

This study aimed to analyze the influence of impression technique (pick-up versus reposition) and material on the accuracy of the working cast. Sixty impressions were made with 3 materials from a master cast with 4 XiVE implants. The changes in the implant axis direction, rotation, and 3-dimensional shift were assessed. The pick-up technique showed significantly (P .05, U test) lower values for axis direction and 3D shift but higher values for rotation than the reposition technique. The differences between the materials were not significant (P > .05, H test). It can be concluded that the impression technique-in contrast to the impression material-has a significant influence on transfer accuracy.

Occlusal force analysis was retrospectively evaluated to clarify the proximal contact loss after fixed implant prosthesis placement. Twenty-eight patients (55 prostheses) with fixed implant prostheses in the posterior region were divided into 2 groups: proximal contact loss and unchanged groups. The occlusal force and its distribution were 3-dimensionally measured using the Dental Prescale system. A high proportion of lingual and anterior component forces and high occlusal force distribution in the intercanine region were observed in the contact loss group. The high occlusal force of the adjacent tooth may enhance the mesial migration.

The aim of this study was to evaluate the change in occlusal force at denture dislodgement (OFD) in patients with poorly fitting complete dentures after improvement. In 91 patients, OFD was recorded before treatment, immediately after fitting the renewed denture (direct effect), and 1 week, 1 month, and 6 months later (adaptation). OFD increased significantly (P .01) after optimizing the dentures and was dependent on patients' gender and age. The greatest changes occurred within the first week. It can be concluded that the increase in OFD is not only induced by the optimized denture, but also - and to an even greater extent - by adaptation.

Purpose: The aim of this clinical retrospective study was to evaluate the survival and success of single metal-ceramic crowns after 20 years. The biologic and technical complications as well as patient satisfaction were recorded. Materials and Methods: Fifty patients treated with 100 single metal-ceramic crowns attended the clinical 20-year follow-up examination. The mean follow-up time was 18.8 years (17.5 to 20.5 years). Results: Twenty-one teeth with single crowns were extracted because of root fractures or esthetic or periodontal reasons. Ninety-seven percent of the subjects had no complaints about the esthetics of the crowns. The most common clinical findings were supragingival crown margins caused by gingival recessions, gingival bleeding on probing, and occlusal wear in opposing teeth. The success of the crowns after 20 years was 75%, and the survival was 78%. Conclusion: In the 20-year follow-up of single metal-ceramic crowns, there were few biologic and technical complications, and patients were satisfied with the crowns. Crown removal was in most cases the result of root fractures in single crowns with endodontic posts.

Purpose: The aim of this study was to compare the clinical performance of metal-ceramic crowns made with an experimental alloy prepared by the Nordic Institute of Dental Materials, containing 15% zirconium and 85% titanium (Ti-15% Zr), and a high noble gold-palladium alloy (Mattikraft). Materials and Methods: Twenty patients who satisfied the inclusion criteria were selected sequentially from the departmental waiting list. Each patient received 2 crowns in the premolar or molar region. Which tooth was to receive a crown based on gold-palladium alloy or Ti-15% Zr alloy was randomly decided. A number of aspects indicating the clinical performance of the crowns were recorded at baseline and after 1, 2, and 3 years. Results: No statistically significant differences between the 2 types of crowns were demonstrated regarding overall technical evaluation, occurrence of plaque, bleeding on probing, or patient satisfaction. Periodontal pocket measurements around Ti-15% Zr crowns were significantly higher than those around gold alloy crowns. However, a similar difference also existed at baseline. Periodontal pocket measurements increased and patient satisfaction improved significantly over time. Conclusions: Within the limitations of this study, the results indicate that there is no difference in the clinical performance of crowns based on Ti-15% Zr or gold-palladium alloy.

This retrospective clinical study investigated the survival of 385 abutment teeth retaining 117 removable partial dentures with 3 types of telescopic abutment retainers. Within a mean service time of 6.26 years, 8.8% of 385 abutment teeth were extracted. Cox regression analysis revealed a significantly higher risk of tooth loss for posterior teeth (odds ratio: 2.985) and for teeth with root canal treatment (odds ratio: 3.298), whereas age, sex, and number and type of telescopic retainer had no influence on survival. Root canal-treated teeth did not show a higher fracture rate, excluding this as an explanation for an increased risk of tooth loss.

Purpose: The clinical success of fixed restorations is linked to the precise reproduction of the prepared teeth by dental impressions. The hypothesis under examination was that neither clinical parameters nor the impression technique influenced the reproduction of the finishing line during impression making. Materials and Methods: For 48 patients who needed a fixed restoration, a 1-stage putty-wash, 2-stage putty-wash, and monophase impression were made after preparation in a randomized order. Clinical parameters (Plaque Index, probing depth, bleeding on probing, Gingival Index, location of the finishing line, bleeding during impression taking, and blood at the impression) were recorded. Master casts were manufactured and optically digitized. Using the data of the 1-stage putty-wash impression as reference, the reproduction of the finishing line was measured 3-dimensionally. Linear models were used for statistical analysis. Results: The finishing line was reproduced most precisely by the 1-stage putty-wash technique. Variables with significant influence were the impression technique, blood at the impression, and probing depth. The 2-stage putty-wash impressions showed significantly reduced accuracy compared with the 1-stage impressions. Conclusion: Clinical parameters and the impression techniques determine the reproduction of the finishing line. The benefit of 2-stage putty-wash impressions with regard to a more complete rendering of subgingival finishing lines should be questioned in light of these results.

Purpose: This literature review aimed to find answers to relevant questions regarding the clinical outcome of endontically treated teeth restored with fiber posts. Materials and Methods: All clinical studies published since 1990 in journals indexed in MEDLINE were retrieved by searching PubMed with the query terms "fiber posts and clinical studies." The reference list of the collected articles was also screened for further relevant citations. The strength of the evidence provided by the reviewed papers was assessed according to the criteria of evidence-based dentistry. Results: Five randomized controlled trials (RCTs) on fiber posts have been published in peer-reviewed journals. A meta-analysis is not applicable to these studies since they do not address the same specific clinical question. Retrospective and prospective trials without controls are also available. Conclusions: Two RCTs indicate that fiber-reinforced composite posts outperform metal posts in the restoration of endontically treated teeth. However, this evidence cannot be considered as conclusive. Longer-term RCTs would be desirable. The placement of a fiber-reinforced composite post protects against failure, especially under conditions of extensive coronal destruction. The most common type of failure with fiber-reinforced composite posts is debonding.

Purpose: This review examined literature that reported functional outcomes across 3 categories of prosthetic treatment after microvascular reconstruction of the maxilla and mandible: (1) conventional dental/tissue-supported prosthesis, (2) implant-retained prosthesis, and (3) no prosthesis. Materials and Methods: Library databases were searched for articles related to reconstruction of the maxilla and mandible, and references of selected articles were hand searched. Relevant literature was identified and reviewed with criteria specified a priori. Results: Forty-nine articles met the inclusion criteria. Twelve articles reported on function after maxillary reconstruction, with the majority of articles reporting on outcomes for 1 to 6 subjects. Thirty-nine articles reported on function after mandibular reconstruction. Speech outcomes were satisfactory across all groups. Swallowing reports indicated that many patients who received either type of prosthetic rehabilitation resumed a normal diet, whereas those without prosthetic rehabilitation were often restricted to liquid diets or feeding tubes. Patients without prosthetic rehabilitation reportedly had poor masticatory ability, whereas conventional prosthetic treatment allowed some recovery of mastication and implant-retained prosthetic treatment resulted in the most favorable masticatory outcomes. Quality-of-life outcomes were similar across all patients. Conclusions: Several limitations of the current literature prevented definitive conclusions from being reached within this review, especially regarding maxillary reconstruction. However, recognition of these limitations can direct functional assessment for the future.