The International Journal of Prosthodontics, 02/2008

The annual search for the best paper published in 2007 provided the usual renewed reading pleasures and selection challenge. Numerous outstanding papers underscored the vast range of eclectic topics and international talents whose work continues to enrich this journal. Several of the outstanding papers were coauthored by experienced members of our editorial board, including Torsten Jemt, Sreenivas Koka, Terry Walton, and Nicola Zitzmann. These colleagues deserve special recognition, even though they were not eligible for the competition. Of course, such seasoned clinical scholars will quite willingly make way for the newer outstanding recruits to the published field of clinical management of patients' oral rehabilitative needs. The clear-cut winner was Hein De Backer from Ghent, Belgium, who together with a number of his colleagues produced a small but impressive canon of work that studied long-term survival of different prosthodontic interventions. His publications in the IJP are a strong reminder of the importance of scrupulous documentation of clinical performance in the context of readily applied evaluative criteria. His was the rearview-mirror clinical approach to determining what is most likely to influence treatment outcomes in specific aspects of the discipline. I congratulate Dr De Backer on behalf of the IJP's 20 associate editors, who undertook the difficult task of selecting the best paper of 2007.

Purpose: The aim of this long-term follow-up study was to collect up to 17 years of survival data of endodontically treated single teeth with or without a prefabricated metal post. Materials and Methods: Single teeth were provided with direct composite resin core-crown reconstructions with or without posts by 15 operators. Restorations consisted of either a prefabricated metal post and a composite core-crown reconstruction or a post-free direct composite reconstruction. Allocation of either restoration was performed by balanced drawing. These restorations were not covered by an artificial crown. The study sample consisted of 87 patients who received 98 core-crown reconstructions. The performance of the restorations was evaluated based on data collected from the files of the clinicians currently monitoring the oral health of the patients. The survival probability was analyzed at different levels: on the restoration level and on the level of the tooth carrying the restoration. Kaplan-Meier analysis was used to compare survival probabilities. Results: Post placement showed no influence on the survival probability at either level (P > .05). The estimated overall survival rate at 17 years was 53% ± 14% at the restoration level and 79% ± 11% at the tooth level. Conclusion: The results of this long-term follow-up study showed no difference in survival probabilities between different direct composite resin core-crown reconstructions of endodontically treated single teeth (with or without a post).

Purpose: The objective of this study was to investigate the initial effects of the vertical thickness of occlusal splints on the electromyographic (EMG) activities (integrated EMG values) of temporal and masseter muscles during sleep in subjects with a nocturnal bruxism habit using a portable EMG recorder. Materials and Methods: The subjects consisted of 12 volunteers (4 men and 8 women, average age of 25.3 years). All subjects had never worn splints before and had a habit of nocturnal bruxism. Two types of splint were made for every subject: a splint with a 3-mm vertical thickness at the central incisors (S3) and a splint with a 6-mm vertical thickness (S6). The muscle activities of the left anterior temporal muscles and masseter muscles were recorded without occlusal splints (NS), with the S3 splint, and with the S6 splint by a portable EMG recorder. The integrated EMG values were calculated to examine muscle activities under the 3 different conditions. Results: The integrated EMG values of masseter and temporal muscles decreased following insertion of the S3 splint but were not significantly affected by the S6 splint. Six subjects in masseter EMG and 7 subjects in temporal EMG got worse with the S6 splint compared to NS. Conclusions: When the occlusal splints were used as a bruxism countermeasure, it was suggested from the analysis of muscle activities during sleep at night that the S3 splint was superior to the S6 splint.

This study compared the vertical misfit of 3-unit implant-supported nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloy and commercially pure titanium (cpTi) frameworks after casting as 1 piece, after sectioning and laser welding, and after simulated porcelain firings. The results on the tightened side showed no statistically significant differences. On the opposite side, statistically significant differences were found for Co-Cr alloy (118.64 µm [SD: 91.48] to 39.90 µm [SD: 27.13]) and cpTi (118.56 µm [51.35] to 27.87 µm [12.71]) when comparing 1-piece to laser-welded frameworks. With both sides tightened, only Co-Cr alloy showed statistically significant differences after laser welding. Ni-Cr alloy showed the lowest misfit values, though the differences were not statistically significantly different. Simulated porcelain firings revealed no significant differences.

Purpose: This study evaluated the outcome of treatments performed by students in the undergraduate implant elective program at Dalhousie University. Materials and Methods: All patients treated with dental implants in the undergraduate elective program at the Faculty of Dentistry, Dalhousie University, Halifax, Nova Scotia, Canada, between 1994 and 2004 were identified from patient records. Brånemark implants (Nobel Biocare) were placed by experienced oral and maxillofacial surgeons or periodontists using the traditional 2-stage protocol and an intermediate healing period of 3 to 6 months. Undergraduate students in the elective implant program were responsible for the restorative part of the treatment. Results: A total of 166 implants were placed in 95 patients (38 men, 57 women; mean age: 52 years, range: 18 to 84 years). Of the 166 implants, 142 had been restored at the time of the study. Ten of the implants failed: 4 were lost during healing and the remaining 6 were lost after loading, leading to an implant survival rate of 93%. A total of 64 single-implant restorations, 7 multiple-unit fixed restorations, and 33 implant overdentures were fabricated. Conclusion: The results indicate that the clinical outcome of implant treatments performed by undergraduate students in the implant elective program at Dalhousie University is similar to that reported by experienced clinicians/research teams. Although the implant surgery was performed by an experienced oral and maxillofacial surgeon or periodontist, the student had the main responsibility for treatment planning and performing the prosthodontic procedures. The results also suggest that implant dentistry could be implemented as part of the curriculum in the undergraduate programs of dental schools.

This study aimed to determine the efficacy of local anesthesia using Oraqix for gingival retraction in 35 healthy adult patients. The median visual analogue scale value was 20.5 ± 24.2 (range: 0 to 81) for pain encountered during the procedure. In most patients, a lower verbal rating scale value corresponded with a lower visual analogue scale value. More than 80% of the operators evaluated the procedure as simple to perform, and more than 65% considered it useful compared with conventional injectable anesthesia. The results suggest that Oraqix is an attractive alternative to injectable anesthesia generally performed for gingival retraction at dental clinics.

Purpose: The aim of this study was to assess and compare clinical outcome results of tooth-implant-supported fixed and removable partial dentures in a selected population group of partially edentulous patients. Biological and technical complications were recorded and reviewed. Materials and Methods: A retrospective analysis of the dental charts of 224 patients (174 men, 50 women) with a mean age of 51.3 years was carried out. The evaluation included details regarding the survival and technical complications of the prescribed prostheses, as well as the biological and technical complications associated with both types of abutments used, ie, teeth and implants. Results: A total of 229 prostheses were supported by 459 implants and 449 teeth. They were monitored for a period of 2 to 10 years (median follow-up time: 6.7 years). At the end of the different observation periods, 14% of the tooth-implant-supported prostheses had undergone technical modifications, with no statistical difference in the occurrence of technical complications between the 2 types of prosthesis. Three of the functionally loaded implants were removed, while 23 abutment teeth were lost (15 had undergone endodontic treatment). Abutment teeth with a reduced attachment level after prosthesis insertion were significantly affected by biological complications (P = .04). Conclusions: The survival data for both types of prosthesis were comparable to prostheses supported solely by implants. There was no difference in the complication rate between primary splinting (fixed) and secondary splinting with telescopic systems (removable). A greater risk of biological complications was recorded for endodontically treated abutments or teeth with a reduced attachment level.

This article presents the use of dental implants for the retention of thumb prostheses. Two patients with traumatic amputation of the thumb were rehabilitated with implant-supported digital prostheses. A dental implant was placed in the residual bone of the thumb. After a 3-month osseointegration period, retentive attachment and silicone prostheses were fabricated. Osseointegration of the implant, peri-implant skin health, and prosthesis function were assessed every 6 months. The follow-up period was 18 months for patient 1 and 21 months for patient 2. Osseointegration was achieved, and there were no skin problems. Some degree of tactile sensation was observed, and the patients were satisfied with the esthetic result.

Purpose: To examine whether there is a gender-dependent risk profile for signs of temporomandibular disorders (TMD) in a population-based sample. Materials and Methods: Sociodemographic, behavioral, and medical factors were checked for associations with TMD in a cross-sectional study of 3,567 subjects aged 25 to 74 years in Germany. Data were collected from clinical examinations, interviews, and questionnaires. Logistic regression analyses were used to estimate factors associated with signs of TMD across gender. TMD signs included tenderness or pain on palpation of 3 or more masticatory muscles and tenderness or pain on palpation in 1 or both temporomandibular joints (TMJs). Results: In women, muscle tenderness or pain was found to be significantly associated with general arthrosis/arthritis and lower back pain. In men, muscle tenderness or pain was significantly associated with school education > 11 years, various categories of loss of occlusal support, lip/tongue/cheek biting, and general arthrosis/arthritis. In women, TMJ tenderness or pain was associated with widowed status, bruxism, general arthrosis/arthritis, lower back pain, and sex-hormone replacement. In men, TMJ tenderness or pain was associated with multiple losses of posterior supporting zones, gout, and lower back pain. In women, there were inverse associations between loss of occlusal support in 3 posterior zones and muscle and TMJ tendernes. Conclusion: Except for some general health conditions and bruxism, the hypothesis of a gender-dependent risk profile for signs of TMD is partly supported. The results of this study indicate that TMD is a complex disorder associated with mixed etiologic factors between genders.

This study aimed to measure mandibular and maxillary anterior tooth display during smiling and speech and to evaluate correlation with age and sex. Ninety-four subjects were video recorded when smiling and when saying "ah" or "shesh." Anterior tooth display was measured using individual video frames. Average mandibular and maxillary anterior tooth display showed opposing trends. The former increased with age, had a tendency to be greater in men, and was greater during speech than during smiling. The latter decreased with age, was greater in women than in men, and was greater during smiling than during speech. Anterior dental esthetic evaluation, especially for the mandible, should include observation of speech.

This in vitro study evaluated the 6-month fatigue retention provided by 5 paired overdenture attachments placed at 3 different interimplant distances (19, 23, and 29 mm). Mean fatigue retention was calculated for each attachment type and compared with the retention produced by the other attachments tested and the initial retention values published earlier. Interimplant distance was found to play a significant role only in the retention of the Hader bar with red and yellow clips. A significant reduction in retention values was observed for 4 of 5 attachment types.

Purpose: The objective of this research was to test the hypothesis that 3-unit fixed partial dentures (FPDs) made from a moderately high-strength core ceramic will adequately resist fracture in posterior regions if fabricated with a minimal connector size of 4 mm. Materials and Methods: Thirty ceramic FPD core frameworks were prepared using a hot-pressing technique and a lithia disilicate-based core ceramic. The maximum occlusal force was measured for each patient prior to tooth preparation. Connector heights and widths were measured for each FPD. Patients were recalled annually after cementation for 4 years and evaluated using 11 clinical criteria. All FPDs were examined by 2 independent clinicians, and rankings for each criterion were made from 1 to 4 (4 = excellent; 1 = unacceptable). Results: The fracture rate was approximately 3% per year, and the proportion of good overall ratings in the nonfractured FPDs was reduced by more than 6% per year, where a good overall rating was defined to be a rank of 3 or 4 in all 11 criteria. There was little evidence that the use of either resin-reinforced glass-ionomer cement (Protec CEM) or dual-cure resin cement (Variolink II) made any difference in terms of fracture rate or overall rating (P = .30, .63, .97, and .71 for the 4 years, respectively). From a fracture resistance perspective, 4 of the 30 ceramic FPDs fractured within the 4-year evaluation period, representing an 86.7% success rate. Another FPD was replaced because of a caries lesion on 1 abutment tooth away from the margin. One FPD fracture was associated with the subject having the greatest occlusal force (1,031 N). The other 2 fractures were associated with FPDs that exhibited connector heights of less than 3 mm. All criteria were ranked good to excellent during the 4-year period for the remaining FPDs. Conclusion: Fractured FPDs were associated with a connector height of less than 4 mm; thus, the hypothesis was accepted.

Purpose: Improvements in the physical properties of modern composites have led to continuous expansion of their field of application to include extensive, occlusion-bearing posterior restorations and even metal-free polymer crowns. The objective of this clinical study was to investigate the influence of gender, arch, and crown location on the occlusal wear of metal-free ceramic-filled polymer crowns and to compare their wear with the mean annual occlusal wear of enamel (15 to 38 µm). Materials and Methods: One hundred fourteen ceramic-filled polymer crowns made of Artglass (Heraeus Kulzer) were placed in 74 patients. After 1 year, 93 crowns were available for wear measurement. After 2 years, 76 crowns were available. Wear was determined by use of replicas. A 3-dimensional optical profilometer (Laserscan 3D, Willytec) was used to digitize and superimpose the occlusal surfaces of the baseline and recall replicas (occlusal matching). Results: After 1 year, median wear of the entire occlusal surface was 19 µm for anterior and canine teeth, 19 µm for premolars, and 21 µm for molars. After 2 years, median wear was 36 µm for anterior and canine teeth, 44 µm for premolars, and 84 µm for molars. The wear of the occlusal contact areas was significantly higher. Significant effects of crown location (premolar or molar) on the extent of wear of the occlusal contact areas were found. Conclusions: Ceramic-filled polymer crowns are subject to measurable occlusal wear that exceeds that of natural enamel.

This study aimed to evaluate the wear resistance of artificial teeth when opposed by antagonists made from the same material. The artificial teeth tested included ceramic teeth, nanofilled composite resin teeth, acrylic resin teeth, and experimental acrylic resin teeth. After 600,000 chewing cycles, the mean total vertical substance loss and mean volume loss for acrylic resin and experimental acrylic resin teeth were significantly lower than for ceramic and composite resin teeth. Composite resin teeth showed more wear than ceramic teeth, while acrylic resin teeth showed less wear than ceramic teeth. However, scanning electron microscopy and laser-scanner observations showed that acrylic resin teeth exhibited deformation at the contact surfaces.

Purpose: To assess esthetic perceptions among Tanzanian adults regarding missing teeth using a cross-sectional clinical study of a convenience sample of 5,532 subjects in the Northern coastal zone of Tanzania. Materials and Methods: The dental status of urban and rural Tanzanian adults (5,532 subjects, ages between 20 and 80 years) was recorded. A structured interview was used to assess esthetic perception (yes/no complaint) considering the location and number of missing teeth. Logistic regression analysis was applied to determine the effects of the variables age (2 groups: £ 45 years vs > 45 years), gender, socioeconomic status (high/middle vs low), and residence (urban vs rural) on the number of complaints. Results: Of the subjects with 1 or more missing maxillary anterior teeth, 54% reported a complaint. Dissatisfaction was reported by significantly more subjects £ 45 years of age and subjects with high/middle socioeconomic status. Gender and residence had no significant influence. Of the subjects with missing maxillary premolar(s) (no missing anterior teeth), 25% reported esthetic complaints (missing first premolar: 24%; missing second premolar: 11%; missing first and second premolar on the same side: 44%). Dissatisfaction was significantly greater in women, subjects £ 45 years of age, and subjects with high/middle socioeconomic status. Residence had no significant influence. Fewer than 1% of the subjects were dissatisfied with missing maxillary molars. Conclusion: Among this group of Tanzanian adults, absence of teeth played a considerable role in the esthetic appreciation of their dentition. Complaints were associated with both number and location of missing teeth.