Fixed partial dentures (FPDs) made of 12% Au-Pd alloy are covered under Japan’s national health insurance system. The survival rate of such 3-unit fixed FPDs remains unknown, however. The purpose of this retrospective study was to assess their survival rate in the replacement of first molars. A total of 140 FPDs were included, and the endpoint was removal of an FPD. During the observation period, 43 FPDs were removed. The FPD survival rate was 70.2% at 10 yr, 58.2% at 15 yr, and 42.1% at 20 yr according to the Kaplan-Meier method. The estimated mean survival period was 19.4 yr. The main reasons for FPD loss were dental caries (27.9%), separation from the abutment tooth (18.6%), and pulpitis (18.6%). Single factor analysis using the log-rank test showed that two factors influenced FPD survival: a smaller gonial angle and deep pockets around the abutment teeth. This effect was not statistically significant in either case, however (p>0.05). The present results suggest that the prevention of caries and of the separation of the dentures from the abutment teeth are important factors in the long-term survival of FPDs.

In this study, original leeway space was determined using plaster models prepared from the same individuals over successive years and compared with that reported in an earlier study. The plaster models used for measurement were prepared from a normal dentition group comprising 64 patients and a crowded dentition group comprising 29. The mesiodistal crown width of the deciduous canines, deciduous first molars, and deciduous second molars, as well as that of the canines, first premolars, and second premolars was measured. Leeway space was then calculated and the results compared with that previously reported. The average maxillary and mandibular leeway spaces calculated in the same individuals were 1.46 and 2.66 mm, respectively, whereas those calculated from data collected from different individuals were 0.89 and 2.83 mm, respectively. No direct statistical comparison of leeway space between this and the earlier report was possible. The present results did indicate, however, that it was larger in the maxilla than previously reported. A larger leeway space is advantageous for the normal arrangement of the permanent teeth. While the mesiodistal crown width of some of the lateral segment teeth in the present study was significantly larger in boys than in girls, no significant difference was observed in leeway space between sexes. The mesiodistal width was larger in multiple permanent teeth such as canines in the crowded dentition group, and this difference was significant in boys. On the other hand, no difference was observed in mesiodistal width in the deciduous teeth between the two groups. These results showed a tendency toward larger teeth and less leeway space in the permanent dentition in the crowded dentition group, which may have been a factor in why such crowding occurred.

This report describes the treatment of severe skeletal Class II malocclusion in a young woman with a gummy smile and pronounced lower anterior facial height. Overjet and overbite were +12.0 mm and −1.0 mm, respectively. Cephalometric analysis revealed inferior positioning of the maxilla and severe mandibular retrusion with clockwise rotation. Both the upper and lower anterior teeth showed labial inclination. Based on a diagnosis of a skeletal Class II high angle with mandibular retrusion and a gummy smile, double-jaw orthognathic surgeries for upper and lower premolar extraction were chosen to gain ideal occlusion and an improvement in the esthetic facial profile. Le Fort I osteotomy was performed to move the anterior and posterior teeth upward by 4.0 mm and achieve mandibular counterclockwise rotation. Short lingual sagittal split ramus osteotomy was performed to move the mandible forward by 3.0 mm. As a result, normal overjet and overbite were achieved together with a straight profile and a good smile. After surgery, electromyographic evaluation of anterior temporal muscle activity showed an improvement in the percentage overlapping coefficient value (a symmetric index of bilateral muscle activity) from 28.1% to 63.2% compared to at pre-treatment. The pattern of jaw movement also showed an improvement. These results suggest that orthognathic surgery in skeletal Class II cases can improve not only malocclusion and the skeletal relationship of the jaws, but also masticatory function and jaw movement.

This report describes a case of periodontitis treated with periodontal surgery including guided tissue regeneration (GTR) and recombinant human fibroblast growth factor (rhFGF)-2. The patient was a 54-year-old woman who visited the Tokyo Dental College Suidobashi Hospital with the chief complaint of swelling in the maxillary right gingiva. An initial examination revealed 30.4% of sites with a probing depth (PD) of ≥4 mm. The prevalence of sites with bleeding on probing was 57.7%. The plaque control record (PCR) score was 66.1%. Radiographic examination revealed vertical bone defects in the molar region. Based on these findings, the clinical diagnosis was generalized chronic periodontitis (Stage III, Grade C). Initial periodontal therapy yielded an improvement in periodontal conditions, with the PCR score reducing to 13.8%. Periodontal surgery was performed for teeth with a residual PD ≥4 mm. Guided tissue regeneration was performed on #37 and 47. A series of periodontal regenerative treatments comprising application of rhFGF-2 was performed on angular bone defects in #14, 15, 25, and 27. Open flap debridement was performed on #16, 17, 26, 36, and 46. Following evaluation, oral function was restored by placing all-ceramic crowns on #21 and 26. The patient was then placed on supportive periodontal therapy. In the present case of generalized chronic periodontitis, periodontal regenerative therapy with GTR and rhFGF-2 yielded stable periodontal conditions.