[Measurement and analysis of the nasopalatine canal and its relative position by cone-beam computed tomography].

OBJECTIVE: To evaluate dimensions of the nasopalatine canal and the relationship between the canal and the central incisors, and the canal and the crest, by using cone-beam computed tomography (CBCT). METHODS: This study included 129 CBCTs, and the sagittal slices were used to measure the lower diameter (Sda), median diameter (Sdb), and higher diameter (Sdc), for calculating the average sagittal diameter (Sd); the coronal slices through canals were used to measure the lower diameter (Hda), median diameter (Hdb), and higher diameter (Hdc) for calculating the average horizontal diameter (Hd), length (H); the sagittal slices were used to measure the buccal bone thickness off the canal (Bt), and the distance to the crest off the lowest point (At), the horizontal slices were used to measure the distance between the canal and the central incisors (Id). These subjects were divided into two groups by gender; and divided into three groups by ages: (1) ≤ 30 years old, (2) 31-50 years old, and (3) ≥ 51 years old. SPSS 17.0 statistical software was used for statistical analysis. RESULTS: The overall Sd was (3.41 ±0.87) mm, the Hd was (5.16±0.93) mm, and the difference was statistically significant. The H was (14.29 ± 3.27) mm, the Bt was (7.49 ± 1.05) mm, the At was (8.25 ± 1.71) mm, and the Id was (2.71±0.89) mm. Of the male and female, the Sd were (3.64 ± 0.90) mm and (3.28 ± 0.82) mm, P=0.017; the Hd were (4.98 ± 0.89) mm and (5.27 ± 0.94) mm, P=0.081; the H were (15.47 ± .75) mm and (13.59 ± 3.32) mm, P=0.001; the Bt were (7.90 ± 0.96) mm and (7.25 ± 1.03) mm, P=0.001; the At were (7.41 ± 1.86) mm and (8.44 ± 1.90) mm, P=0.001; the Id were (2.71 ± 0.87) mm and (2.72 ± 0.91) mm, P=0.983. Among the groups, no statistically significant differences were detected of the Sd (P=0.325), of the Hd (P=0.636), of the H (P=0.292), and of the Bt (P=0.116); statistically significant differences were detected of the At (P=0.010), and of the Id (P<0.001). CONCLUSION: The nasopalatine canal anatomy is highly variable. Gender is related to the nasopalatine canal length, Bt width, and At distance. While age was related to At, and Id, but no effect on nasopalatine dimensions. The CBCT is a useful device for studying the nasopalatine canal in three dimensions, prior to dental implant placement.

[Comparison of soft and hard tissue stability between immediate implant and delayed implant in maxillary anterior region after loading 2 years].

OBJECTIVE: To compare the peri-implant tissue stability between immediate implant and delayed implant in maxillary anterior region after loading 2 years. METHODS: In the study, 38 patients with single anterior tooth loss in the Second Clinical Division of Peking University School and Hospital of Stomatology from October 2010 to December 2011 were enrolled, and 43 implants were inserted. The gingival contour was induced using implant-supported temporary crowns prior to restoration till permanent prostheses delivered. The gingival papilla height, labial gingival margin level and peri-implant bone level were measured immediately after the permanent restoration and 2 years later. RESULTS: In the study, 16 patients were treated by immediate implant for 17 implants; 22 patients were treated by delayed implant for 26 implants. The implant stability quotient (ISQ) value of the 2 groups showed no significant difference before permanent restoration (P>0.05). In all the cases after loading 2 years, the average mesial gingival papilla height in the implant area of the immediate group and delayed group increased by (0.15 ± 0.42) mm and (0.06 ± 0.65) mm, respectively; the distal gingival papilla height increased by (0.06 ± 0.50) mm and (0.02 ± 0.57) mm respectively; while the labial gingival margin level shrinkages were (0.15 ± 0.23) mm and (0.15 ± 0.46) mm, respectively. The peri-implant bone losses in the mesial side were (0.67 ± 0.35) mm and (0.6 9 ± 0.49) mm, respectively, while in the distal side were (0.73 ± 0.31) mm and (0.75 ± 0.48) mm, respectively. All these indicators showed no significant difference between the 2 groups (P>0.05). CONCLUSION: Both the cases obtained optimizer results after loading 2 years, and the soft and hard tissues around the implant were very stable, which means that both the protocols can achieve reliable therapeutic effects. If we can handle the indications, immediate implant for anterior teeth shows similar efficacy with delayed implant in the short term. But immediate implant in terms of shortening the course of treatment is clearly superior to delayed implant.

[Evaluation of short-term clinical therapeutic efficiency of computer aided design and manufacturing titanium-ceramic-fixed partial dentures for implant-supported restoration in posterior region].

OBJECTIVE: To evaluate the clinical results of computer aided design and computer aided manufacturing (CAD/CAM) titanium-ceramic-fixed partial dentures for implant-supported restoration in posterior region. METHODS: In the study, 90 patients (47 males, 43 females, and the mean age of 48.7 years ranging from 30-62 years) with posterior tooth missing underwent implant-supported porcelain fuse mental prostheses with CAD/CAM titanium-base. A total of 135 prostheses (159 prosthetic units) were fabricated, and 152 implants were placed. The evaluators examined the integrity of restoration, gingival health, color match and marginal adaptation. The mean follow-up time was 51.9 months (24-80 months). RESULTS: No implant was lost during the loading time. All the patients were satisfied at the end of their treatment. The chipping rate of porcelain fuse mental prostheses with CAD/CAM titanium-base was 13.2%(21/159 prosthetic units), No fracture of titanium-base was observed, and 7.4% (10/135) prostheses were found loosening. The authors rated 97.8% (132/135) prosthesis as good or better in regard to color match, 100% (152/152) implants had excellent marginal adaptation. CONCLUSION: The implant-supported titanium-based porcelain fuse mental prostheses with CAD/CAM show good marginal integrity and shade stability, with a clinically acceptable chipping rate, and these restorations can achieve success in the case of posterior tooth missing. Further study is needed to determine the long-term results.

Evaluation of the therapeutic efficiency of mandibular anterior implant-supported fixed bridges with cantilevers.

BACKGROUND: Dental implant technology has developed rapidly in recent years. However, the use of implant-supported fixed bridges with cantilevers has been controversial. The purpose of this study was to evaluate the clinical results of the mandibular anterior implant-supported fixed bridges with a cantilever. Method Thirty-three patients (15 males, 18 females; mean age, 42.6 years; range 20-54 years) with two missing anterior mandibular teeth had single implant-supported fixed bridges with a cantilever. Clinical examination was recorded and radiographs were taken. The mean duration of follow-up was 30 months (15-44 months). RESULTS: All implants survived. Loosening or fracture of the prosthesis was not observed. All patients were satisfied with the treatment. The mean bone resorption values after 12, 24, and 36 months of implant loading were 0.94, 1.18 and 1.35 mm respectively. The changes of gingival papilla height ranged from 0 to 0.5 mm. There was significant difference between 1-year and 2 or 3 years restoration groups regarding the average gingival height changes (P < 0.05). CONCLUSION: After careful and precise selection of patients, restoration with a single implant-supported fixed bridge with a cantilever can be recommended if two anterior mandibular teeth are missing.