[Clinical observation of the curative effect after 5-year follow-up of single tooth implant-supported restorations in the posterior region].

OBJECTIVE: To analyze the clinical curative effect after 5-year follow-up of single tooth implant-supported restorations in the posterior region. METHODS: In the study, patients with single tooth implant-supported restorations in the posterior region after loading 5-year in the Second Clinical Division of Peking University School and Hospital of Stomatology from October 2005 to May 2010 was enrolled. The implant survival rate, prosthetic conditions (including the structural integrity or loosening of the prosthesis, the retention of the materials used to fill access holes of screw-retained implant crowns, loosening or fractures of the implant abutment or screw) and marginal bone lever level around implants were determined by clinical and radiographic examination. RESULTS: The study was composed of 215 patients, the mean age was 48.6 years (range: 27 to 71), and 321 soft tissue implants were inserted. There were 9 implants loose and lost during the visit, the cumulative success rate was 97.2%. In the 312 remaining implants, 120 implants were placed in the upper jaws (38.5%) and 192 in the lower jaws (61.5%). Three different diameters as 3.3 mm (5 implants), 4.1 mm (115 implants) and 4.8 mm (192 implants) and three different lengths as 8 mm (21 implants), 10 mm (206 implants) and 12 mm (85 implants) were used, respectively. 277 (88.8%) cement-retained and 35 (11.2%) screw-retained implant-supported single crowns were made. The marginal bone loss (MBL) around dental implants after loading 5 years in the mesial and distal sides were (0.73±0.25) mm and (0.78±0.26) mm, respectively. There was no significant difference among MBL and bone quality, implant type, angle of abutment, prosthodontic type, crown-to-implant ratio, gender, and age of the patients (P > 0.05). The major mechanical complications after restoration involved loosening (8.6%) and fracture (2.9%) of the crown retainer screw, loss of resin covering the screw (11.4%), and the most frequent mechanical complications were loss of crown retention (14.1%) and fracture of porcelain (13.8%). The incidence of loss of crown retention was correlated with insufficient clinical crown height or using angle abutment (P < 0.05). CONCLUSION: After loading 5 years, the bone level around the soft-tissue-implant placed in posterior region was stable. To minimize the frequency of mechanical complications after restoration, protocols must be established from diagnosis to the completion of treatment and follow up of implant-supported prostheses, especially in terms of adequate technical steps and careful radiographic evaluation of the components.

[A prospective study on the application of 6-mm-long implants in the upper and lower posterior edentulous regions].

Objective: To assess clinical and radiographic outcomes of short implants (length six mm) in the posterior region and early-loading with splinted fixed dental prostheses. Methods: Forty-five patients were recruited at 3 centers and 2-3 implants (diameter 4 mm, length 6 mm) were implanted in each case. Totally, ninty-five implants were placed, using one-stage surgery protocol and loaded with a screw-retained splinted fixed prosthesis 6 weeks later. Clinical and radiographic examinations were performed preoperatively, post-surgery, at loading, and 6, 12 and 24 months after prosthesis placement. Results: Four implants were removed before loading. A total of 36 patients with 76 implants completed the whole treatment and 2 year follow-up according to the research design. No implant was lost after loading, and the 2-year survival rate of the implant was 100%(76/76). In all cases, the response of swelling and pain after operation was mild, and the bone resorption around the implants was not obvious at 6 months [(0.04±0.29) mm], 1 year [(-0.11±0.44) mm], and 2 years [(0.00±0.53) mm] after loading. Bone loss less than 1.00 mm was found only in 26% (18/69) implants after 2 years of loading, and the height of the alveolar bone around 17% (12/69) of the implant increased. During 2-year follow-up, the probing depth of the implants increased by nearly 0.50 mm, but there was no clinical significance (P>0.05). Conclusions: The 2-year results of this study showed that the 6-mm-long implants can be a predictable procedure, especially in situations with limited bone height in posterior edentulous regions.

[Clinical observation on soft and hard tissue changes of immediate implantation and immediate reconstruction in anterior region after loading 3 years].

OBJECTIVE: To observe the change of soft and hard tissue in dental immediate implantation and immediate reconstruction in anterior region after loading 3 years. METHODS: Patients with single anterior tooth loss in the Department of Second Dental Center, Peking University School and Hospital of Stomatology from October 2008 to October 2012 were enrolled. The gingival papilla height, labial gingival margin level and peri-implant bone level were measured immediately after the permanent restoration and 3 years later. RESULTS: In the study, 20 patients were treated by immediate implantation and immediate reconstruction for 22 implants; 24 patients were treated by delayed implant for 29 implants. Implant stability quotient (ISQ) value of the two groups showed no significant difference before permanent restoration (P>0.05). In all the cases after loading 3 years, the average mesial gingival papilla height in implant area of the immediate group and delayed group changed by (0.34±0.54) mm and (0.05±0.39) mm respectively (P=0.07), the distal gingival papilla height changed by (0.43±0.42) mm and (0.36±0.48) mm respectively (P=0.13), while the labial gingival margin level shrinkages were (0.70±0.40) mm and (0.62±0.34) mm respectively (P=0.23). Peri-implant bone losses in the mesial side were (1.02±0.50) mm and (0.88±0.46) mm respectively (P=0.53), while those in the distal side were (1.05±0.34) mm and (0.95±0.47) mm respectively (P=0.21). All these indicators showed no significant difference between the two groups (P>0.05); When the permanent prostheses delivered, the distributions of the gingival papilla index were different between the two groups whether in the mesial side or in the distal side (P<0.05). CONCLUSION: The changes of the soft and hard tissue of the immediate implantation and immediate reconstruction in anterior region after loading 3 years were basically equivalent to the conventional implant restoration. But, the former was obviously better than the latter in reducing the duration of treatment and in getting the ideal dental papilla aesthetic effect.

[Clinical observation of the reliability of gingival contour by using temporary crown after loading 1 year].

OBJECTIVE: To observe the gingival contour and its variation following application of implant-supported temporary crowns on gingival contour in maxillary single tooth implant procedure after loading 1 year and to explore the reliability of soft tissue intervention using temporary crowns. METHODS: In 78 (37 males and 41 females) patients with anterior maxillary single tooth loss from the Department of Second Dental Center, Peking University School and Hospital of Stomatology, the gingival contour was induced by using implant-supported temporary crowns prior to maxillary tooth implant till permanent restoration from March 2010 to November 2011. The gingival papilla height and labial gingival margin level were measured immediately after the permanent restoration and 1 year later. RESULTS: In all the cases after loading 1 year, the average mesial and distal gingival papilla heights in the implant area increased by (0.16±0.58) mm and (0.10±0.53) mm, respectively. The labial gingival margin level was changed by (0.10±0.41) mm averagely. The difference in gingival contour shaped by temporary crown was not statistically significant after 1 year (P>0.05). CONCLUSION: The soft tissue shaping technique on aesthetic rehabilitation in maxillary single tooth implant is clinically feasible with a good recent aesthetic effect under the condition that the complications are controlled stringently.