[Implanting the edentulous jaws with "All-on-4" immediate reconstruction: a preliminary clinical observation].

OBJECTIVE: To evaluate the treatment outcome of the "All-on-4" immediate loading protocol via survival rate of the implants,survival rate of the prosthesis,marginal bone, postoperative complications and patient satisfaction. METHODS: In our study, 40 patients with 49 edentulous jaws (31 mandibles and 18 maxillae) were enrolled. Each jaw was restored by the shortened dental arch prosthesis supported by only 4 implants according to the All-on-4 protocol (All-on-4, Nobel Biocare AB, Goteborg, Sweden). For all the patients enrolled in the study, the loading was applied within 12 hours of surgery. The provisional prosthesis could be replaced by the final restorations within 6 to 12 months. In the present study, the survival rate of the both implants and restorations were calculated and analyzed. The radiographic evaluation of marginal bone level changes was measured. The values of the marginal bone level changes of the angled and axial implants were analyzed by the statistic software. RESULTS: In the present study, totally 196 implants were inserted, of which 13 implants failed during the whole following up periods, with 11 implants of the maxillae and 2 of the mandibles. The survival rate of the prosthesis was 95.9% (47/49). The implant survival rate of the maxillae was 85.5% (65/76)while that for the mandibles was 98.3%(118/120). The implant survival rate of the angled implants was 91.8% (90/98), while that for the straight implants was 95.0% (93/98). No significant difference in marginal bone loss was found between angled and axial implants in the 12-month evaluation according to the Wilcoxon rank sum test (P>0.05). During the follow-up period,mechanical complications as fracture of the provisional prostheses, loose of the retain screw, or crack of the artificial teeth were found in 20 prostheses. CONCLUSION: The present preliminary data of the short term observation suggest that the "All-on-4" immediate loading protocol is a viable treatment modality for the edentulous jaws. However, long term clinical random controlled trials with large samples are still needed to confirm the validity of the technique.

[Influence of the placing depth of implants with platform switching on the marginal bone level in the posterior mandible: a clinical study].

OBJECTIVE: The purpose of this study was to evaluate the influence of the placing depth of the implants with platform switching (Ankylos) on the marginal bone remodeling, by means of radiological observation. METHODS: 111 Ankylos implants in the posterior mandible from 46 patients (20 male and 27 female) were enrolled in this study. Followed up by 58.1 months on average (from 36 to 85), 222 mesial and distal sites of these implants were evaluated by means of measuring the level of the marginal bone (LMB) on the panoramic radiograph. RESULTS: Among these 111 successfully functional loaded implants, there were no significant differences with the marginal bone absorption values, no matter the implants were placed below, at, or above the bone level (P>0.05). Concerning the stabilization of the marginal bone, when placed below the bone level, 67.7% of the implant sites had their LMBs stabilized at or above the implant platform, and 23.3% absorbed vertically, respectively 19.7% and 80.3% when placed at the bone level, with significant difference (P<0.001). CONCLUSION: Based on a long-term (over 3 years) observation, the implants placed below, as compared to at or above, the alveolar crest level, might have more chance to keep the marginal bone stabilized at or above the implant platform.

A Single-Visit Technique for Fabricating Interim, Immediately Loaded Implant-supported Full-arch Prostheses with Prefabricated Rigid Connecting Bars: a Case Report.

Traditional techniques for fabricating interim, immediately loaded implant-supported full-arch prostheses are complex and time-consuming. The present study presents an efficient technique for fabricating interim prostheses with prefabricated multipurpose rigid connecting bars. This technique can minimise the misfit attributed to the polymerisation shrinkage of resin and expansion of the working cast, and simultaneously facilitate impression taking and occlusal records in one visit, thus reducing laboratory and chair time. Due to its ease of use and clinical efficiency, the present technique is considered particularly beneficial for immediate loading rehabilitation.

[Implant restoration for patients with congenital missing teeth].

OBJECTIVE: To evaluate the treatment plan, clinical outcome and related problems in patients with congenital missing teeth. METHODS: From November 2000 to February 2009, thirty seven patients with congenital missing teeth underwent thorough diagnostic workup, treatment planning and an interdisciplinary approach to ensure optimal treatment in Department of Implant Dentistry, Peking University, School and Hospital of Stomatology. A standard follow-up protocol was conducted for all the patients. RESULTS: The enrolled cases in this study were classified in to 3 types: single tooth missing, multiple teeth missing and edentulous. Among them single tooth missing was found in 21 cases, multiple teeth missing was found in 12 cases and 4 cases were edentulous. 120 implants were placed and restored in 37 patients with the mean follow-up 39.3 months (10-109 months) after prosthetic functioning. Two implants lost after function about 6 months and the remaining implants functioned well until the last review. No adverse complications such as pain and nerve trauma was observed and the mean bone resorption was 1.91 mm. CONCLUSION: An interdisciplinary approach ensures optimal treatment for patients with congenital missing teeth. Implant restorations provide an alternative way with predictable clinical results.

[Clinical study of the application of non-invasive porcelain veneer to improve the aesthetic effects in maxillary anterior area].

OBJECTIVE: To evaluate the clinical results of application of non-invasive porcelain veneer to reduce the black triangle of implant and adjacent teeth and to improve the aesthetic effect in the maxillary anterior area. METHODS: The study included 10 patients (Male: 4, Female: 6; average age: 41.5) accessioned during May 2007 to August 2009 in Peking University School of Stomatology. The provisional restorations were delivery on implant after 3-6 months healing period of the implant. The non-invasive porcelain veneers were used in the round tip adjacent teeth with gingival recession in the indicated patients. Main measured parameters on the model included horizontal distance and vertical distance. The Horizontal distance refers to the black triangle bottom which is from adjacent surface of the natural teeth to the implant restoration at the gingival level. The vertical distance is from mid-point of the triangle bottom to the contact point. Clinical observed items included bleeding index (BI), integrity of porcelain veneer and degree of satisfaction of the patients. RESULTS: A total of 14 adjacent natural teeth in 10 patients were cemented with porcelain veneer. No porcelain veneer was lost or fracture during follow-up period (range 6 to 27 months, mean of 10.4 months). Mean bleeding index 0-1. The horizontal distance was reduced from (3.1 + or - 0.8) mm before restoration to (1.1 + or - 0.5) mm after restoration. Vertical distance from (5.3 + or - 1.1) mm to (2.9 + or - 0.7) mm. All patients were satisfied with the clinical result. CONCLUSION: The data and the experience described in this study indicate that improvement of aesthetic effects by using no-invasive porcelain veneer techniques can be a predictable technique for patients with periodontal disease. Further study is needed to determine the long-term result of the technique.

[Clinical study of free palatal connective tissue grafts for enhancement of periimplant soft tissue topography in maxillary esthetic area].

OBJECTIVE: To evaluate the results and clinical characteristics of free palatal connective tissue graft in closing of immediate implant wound and reconstructing of labial soft tissue topography. METHODS: A total of 285 cases underwent free palatal connective tissue graft transplantation in the implant treatment from June 1997 to June 2006 were included in this study. All cases were followed up for at least one year (1 to 8 years). RESULTS: 4 grafts in 3 cases had necrosis. The other 295 grafts survived well. Following Jemt classification of papilla, 127 cases reached II degree, and 18 cases reached III degree one year after prostheses. 87 cases had no concave defect of labial soft tissue. CONCLUSION: It is effective and predictable to preserve and reconstruct periimplant soft tissue topography with palatal free connective tissue grafts in maxillary esthetic area.

[Clinical study on utilizing free palatal mucosa flap in reconstructing peri-implant attached soft tissue].

OBJECTIVE: To evaluate the results and clinical characteristics of free palatal mucosa flap in reconstructing peri-implant attached soft tissue. METHODS: 126 cases with partial edentulous or edentulous were undergone soft tissue reconstruction and implant treatment from July 1997 to June 2005. A total of 388 implants were placed. The mean follow-up period was over 13 months. Mucosa flaps were measured at the operation and compared the size changes one year after operation. RESULTS: Necrosis occurred in 3 mucosa flaps out of 126 cases 10 days postoperatively. Mean shrinkage of mucosa flap was 56%(37%-70%). No loss of implant was found in the last follow-up and attached soft tissue width was over 3 mm in 371 implants. Eight implants were diagnosed as peri-implantitis (2.06%). CONCLUSION: It is effective and predictable to reconstruct peri-implant attached soft tissue with free palatal mucosa flap.

[Clinical study of immediate post-extraction implant and immediate function in edentulous patients].

OBJECTIVE: To evaluate the outcomes of immediate post-extraction implant and immediate function according to All-on-4 immediate concept in edentulous patients. METHODS: The study included 46 patients with hopeless teeth. A total of 254 implants were immediately inserted after extraction and 56 fixed complete-arch all-acrylic prostheses finished and functioned on the day of extraction from June 2008 to March 2012 in Peking University School of Stomatology. At time of abutments connection, a panoramic radiograph was taken, and radiographic assessment of the marginal bone level was performed in every 6 months. Marginal bone level, integrity of the restoration, survival of the implants and degree of satisfaction of the patients were evaluated. RESULTS: A total of 254 implants were immediate loading. Thirteen implants were lost 6 - 8 weeks after immediate loading and the survival rate of 94.9% (241/254). The marginal bone absorption was (0.7 ± 0.3) mm on average. All patients were satisfied with the clinical results. CONCLUSIONS: Immediate post-extraction implant and immediate function technique can be a predictable technique. Further study is needed to determine the long-term results of the technology.

The All-on-Four implant therapy protocol in the management of edentulous Chinese patients.

PURPOSE: To evaluate the outcome and special characteristics of immediate implant rehabilitation using the All-on-Four treatment concept in completely or potentially completely edentulous Chinese patients. MATERIALS AND METHODS: A convenience sample consisted of 69 consecutive patients (37 men, 32 women; mean age: 56.7 years) treated with immediate implant placement and full-arch prosthodontic provisional prostheses between April 2008 and December 2011. Of 344 implants (192 mandibular, 152 maxillary), 240 implants were placed in fresh extraction sites. The remaining 104 implants were placed in healed sites. Implants were immediately loaded with a fixed full-arch provisional prosthesis. Implant survival rate, marginal bone loss, abutment selection, complications, and subjective patient responses were recorded during follow-up. RESULTS: Implant survival rate was 96.2% at 33.7 months of mean follow-up (range: 12 to 56 months). A statistically significantly higher implant survival rate was found in the mandible (99.0% vs 92.8%) (P < .05). No significant difference existed between survival rates for implants placed in postextraction sites and healed sites (P > .05). Peri-implant marginal bone loss around upright implants and tilted implants was 0.7 ± 0.2 mm and 0.8 ± 0.4 mm, respectively. All patients reported satisfactory treatment outcomes. CONCLUSIONS: The modified All-on-Four treatment concept provides predictably favorable outcomes in completely or potentially completely edentulous patients and is well suited to the sociodemographic needs of Chinese patients. Exploratory use of a surgical guide was limited because of mouth opening, and more angulated abutments were needed in anterior upright implants of the maxilla.

[Clinical study of prosthetic gingival reconstruction in vertical bone defect patients].

OBJECTIVE: To evaluate the preliminary clinical results of prosthetic gingival reconstruction in vertical bone defect patients. METHODS: The study included 31 partial or edentulous patients (male 22, female 9) with 152 implants supporting fixed prostheses from February 2002 to January 2011 in Peking University School and Hospital of Stomatology. The implant-supported fixed prostheses with artificial gingival material to compensate for vertical defect were delivery after implant healing period. At time of prostheses delivery, a panoramic radiograph was taken. The results were evaluated according to California Dental Association by two prosthodontists. Clinical observation included survival of the implants, integrity of the restoration, complication of prosthesis and degree of satisfaction of the patients. RESULTS: A total of 152 implants supported fixed prostheses with artificial gingival materials to compensate vertical bone defect were delivered. No implants lost, and the survival rate was 100% during the follow-up period. The sore of acceptance of prosthesis was 96.8%. All patients were satisfied with the clinical results. CONCLUSIONS: The artificial gingival reconstruction technique is feasible for vertical bone defect patients.

Multidisciplinary management of congenitally missing teeth with osseointegrated dental implants: a long-term report.

OBJECTIVE: To describe a multidisciplinary approach to ensure optimal treatment and timing of treatment for these patients. METHODS: Ten patients with congenital missing teeth were treated with dental implants with a multidisciplinary approach, including orthodontics, prosthodontics, and/or orthognathic surgery, from 1997 to 2006 in the Department of Implant Dentistry, Peking University, Hospital of Stomatology. All patients were followed up over five years. Clinical and radiographic examinations were conducted for all the patients. A thorough diagnostic workup was used and the outline of the treatment planning was given from the prosthodontic point of view. RESULTS: A total of 31 implants were placed and restored for the 10 patients involved. Followup averaged 108.4 months (61-155 months) after implant prosthetic functioning. With the multidisciplinary approach, a satisfactory treatment for these patients was acquired, with follow-up for more than 5 years. The peri-implant marginal bone level was stable with bone resorption averaged 1.97 mm. Peri-implantitis was found in one patient with two implants and effectively treated with local anti-infection. Ceramic chips were observed in two cases and the crowns were re-fabricated. CONCLUSION: Implant restoration with an interdisciplinary approach provides an alternative way with predictable clinical results for patients with congenitally missing teeth.

[A long-term retrospective clinical study of short dental implant restoration].

OBJECTIVE: To evaluate the long-term results of short implants and assess its clinical importance. METHODS: A total of 77 short implants were consecutively placed in 43 patients from August 1998 to August 2004. The clinical data was reviewed and the crown-implant ratio (C/I) was measured. Twenty-nine short implants in 15 patients were loaded for more than 5 years and the marginal bone height around implant measured. The implant success and survival ratio were evaluzted according to Zarb's successful criteria and Wheeler's survival criteria. RESULTS: The mean follow-up time was 5.4 years (36 ∼ 99 months). Among these 77 short implants, 74 implants were fixed restoration, which mean C/I was (1.08 ± 0.21), 3 implants were removable restoration. Of 29 short implants which were loaded for more than 5 years, the mesial bone height at the times immediately after inserting implant, before second stage surgery, loading for less than 3 years and loading for more than 5 years was (0.59 ± 0.66), (0.64 ± 0.59), (-0.05 ± 1.11), (-0.37 ± 1.29) mm; and the distal bone height was (0.62 ± 0.77), (0.60 ± 0.86), (-0.26 ± 1.12), (-0.23 ± 1.59) mm. The 5 year's survival rate and success rate were 97% and 93% respectively. CONCLUSIONS: The success and survival rate of short dental implant under function were comparable to those reported for normal implants. By using the short implant, the patients can avoid the graft operation, alleviate sufferings, shorten the treatment period and reduce the cost. Therefore, it has a high value in clinical application.

[Clinical study of "All-on-4" implant immediate function in edentulous patients].

OBJECTIVE: To evaluate the preliminary clinical results of application of All-on-4 immediate function in edentulous patients. METHODS: Twenty nine edentulous patients with 140 immediately loaded implants supporting fixed complete-arch all-acrylic prostheses from April 2008 to October 2009 in Peking University School of Stomatology were included. The implant-supported fixed complete-arch all-acrylic prostheses were delivery on the operation day. At time of abutments connection, a panoramic radiograph was taken. And radiographic assessment of the marginal bone level was performed in every 2 months. Clinical observe items included marginal bone level, integrity of the restoration, survival of the implants and degree of satisfaction of the patients. RESULTS: A total of 140 implants were immediate loading. Eight implants were lost during 6 - 8 weeks after immediate loading, giving survival rate of 94.3%. The marginal bone level was (0.8 ± 0.4) mm. The All patients were satisfied with the clinical results. CONCLUSIONS: The data and the experience described in this study indicate that All-on-four immediate function technique can be a predictable technique for edentulous patients. Further study is needed to determine the long-term result of the technology.

[An animal study of peripheral neurophysiologic mechanism in osseoperception phenomena of dental implant].

OBJECTIVE: To investigate the existence of functional neuroreceptors in peri-implant bone tissue and to test the peri-implant neural feedback pathway reconstruction and its influential factors. METHODS: Three beagle dogs were involved in this study. After the extraction of 3 premolars and 1 molar of the bilateral mandible, 27 implants were placed immediately or delayed. The implants were loaded for 3 - 6 months, then sensory nerve action potential (SNAP) tests were performed. The stimulating electrode was connected to the implant or natural tooth. The recording electrode was fixed near the inferior alveolar nerve (IAN) to record the latency period and amplitude of SNAP. The specimens with peri-implant bone tissues were taken and examined by immunohistochemistry. RESULTS: SNAP of IAN could be recorded following stimulations to natural teeth and implants. The differences in SNAP amplitudes between natural teeth [(44.04 +/- 6.23) microV] and all implant groups were statistically significant (P < 0.01). Free nerve endings and nerve tract were found in the peri-implant bone tissue, but much less than those in periodontal membrane. Some nerve fibers were directly connected with implant surface. CONCLUSIONS: Functional neuroreceptors, though much less than that of natural tooth, exist in peri-implant bone tissue. Surgical methods and loading time do not have obvious influences on peri-implant neural feedback pathway reconstruction.

[Clinical study of tissue preservation of extraction socket with Bio-Oss collagen and acellular dermal matrix].

OBJECTIVE: To evaluate the clinical and histological results of extraction socket preservation using Bio-Oss collagen and acellular dermal matrix (ADM). METHODS: From November 2005 to June 2006, a total of 11 cases underwent extraction socket preservation with Bio-Oss collagen and ADM in 14 extraction sites. Ten cases with 10 teeth undergoing extraction without bone graft served as control group. Clinical and histological examinations were conducted. Pre-and postoperative alveolar ridge width and attached gingival width were measured and statistically analyzed. RESULTS: All the grafted sockets healed uneventfully except one. Thirteen implants were placed 3 - 5 months after extraction. After 4 to 6 months permanent restorations were delivered. The mean follow-up time was 27.9 months (24 to 31 months). In the control group the sockets healed uneventfully, while hard and soft tissue collapsed obviously 3 months after extraction. No significant difference was found in the width of alveolar ridge and attached gingiva before and after extraction in the bone graft group (P > 0.05). The width of alveolar ridge before (7.69 + or - 0.48) mm and after extraction (7.68 + or - 0.48) mm and in the width of attached gingiva before (4.36 + or - 1.02) mm and after extraction (4.32 + or - 0.98) mm in the bone graft group (P > 0.05). Histological examination showed adequate new bone formation around Bio-Oss particles 3 months after operation. The specimen was free of inflammatory cells. CONCLUSIONS: It's effective to preserve the extraction sockets with Bio-Oss collagen and ADM and the short-term results were predictable.

[A clinical study on orthodontic treatment after tooth autotransplantation].

OBJECTIVE: To evaluate the pulp vitality, the periodontal condition and the success rate of autotransplanted teeth after orthodontic treatment. METHODS: A total of 20 permanent teeth (one of them had been treated by root canal therapy), 17 with completely developed roots and 3 with developing roots, were autotransplanted to the region of missing teeth in 16 admitted patients. Orthodontic treatment was carried out in all cases. Clinical and radiographic evaluation of the transplanted teeth was done. RESULTS: The average time of postoperative orthodontic treatment was 1.9 months. In all, one autotransplanted tooth was lost because of periodontal disease during follow-up. Eight autotransplanted ones had positive electric pulp testing (EPT) response. Fifteen out of 20 autotransplanted teeth were surrounded by newly-formed periodontal space with normal size and lamina dura. The numbers of surviving and successful autotransplanted teeth were 19 and 15, respectively, after an average observation period of 24.5 months. CONCLUSIONS: Orthodontic treatment of autotransplanted teeth was acceptable and the pulp vitality of the teeth might be preserved.

[Clinical study of application of platform switching to dental implant treatment in esthetic zone].

OBJECTIVE: To evaluate the clinical results of dental implant treatment with platform switching technique in esthetic zone and to investigate its technical characteristics. METHODS: Seventeen patients who were partially edentulous in esthetic zone were included and received a total of 26 Frialit-2 system implants in Center of Dental Implantation, Peking University School and Hospital of Stomatology from January to December 2001, and the platform switching technique was applied. The mean follow-up time was 56.3 months (24 to 74 months). Clinical examination and X-ray were conducted. RESULTS: Clinical results of all implant restoration that used platform-switched abutments were satisfied. No implant loss or other severe complications occurred. The medians of marginal bone loss 1 year and 5 years after final restoration was 0.13 (-0.12 - 0.55) mm and 0.27 (-0.04 - 0.77) mm respectively. The medians of interimplant crestal bone resorption was 0.14 (0.00 - 0.30) mm and 0.21 (0.09 - 0.31) mm after 1 year and 5 years' functional loading respectively. According to Jemt classification of papilla, 23 sites reached II degree, and 10 sites reached III degree among 36 sites 5 years after prostheses. The mean value of pink esthetic score (PES) was 11.8 (10 - 14). CONCLUSIONS: Platform switching is a simple and reliable technique for dental implant treatment, helping to control marginal bone loss and ensure an esthetic results in the esthetic zone.

[Minimally invasive extraction and immediate implant placement with single-stage surgical procedure: a clinical observation of 21 cases].

OBJECTIVE: To evaluate the clinical results of minimally invasive extraction without flap reflection and immediate implant placement with single-stage surgical procedure. METHODS: Twenty-one patients (23 single-tooth implants) were included in the study. Eight fractured teeth and 15 residual roots in the maxillary anterior region were extracted without flap reflection and implants placed immediately. Special gingival former was connected at the same time of implant placement with single-stage surgical procedure, final prostheses were restored after 6 months. The follow-up time was from 13 months to 51 months (mean: 27.6 months) after final restoration. Clinical and radiographic study were conducted, the interproximal papillae were analyzed according to Jemt's classification and the level of soft-tissue margin and buccal soft tissue color were evaluated according to Fürhauser's method. RESULTS: All 23 implants acquired osseointegration, and the level of marginal bone at the mesial and distal aspects of all implants were stable. The mesial and distal papilla index score of 3 were observed in 18 implant sites, the papilla index score of 2 in 5 implant sites. Harmonious relationship of gingival margin between peri-implant restorations and adjacent natural teeth was observed in 15 implant sites. The color of buccal soft tissue matched that of the adjacent natural teeth in 18 implant sites, 5 sites showed minor discrepancies. All the patients were satisfied with the final restoration. CONCLUSIONS: Minimally invasive extraction without flap reflection and immediate implant placement with single-stage surgical procedure is a sensitive technique. Many factors may affect the final results and the strict control of indication is the key factor.