Combined use of xenogeneic bone substitute material covered with a native bilayer collagen membrane for alveolar ridge preservation: A randomized controlled clinical trial.

AIM: The aim of this split-mouth randomized controlled study was to evaluate radiographic dimensional changes after tooth extraction in posterior sites treated with a ridge preservation technique or left for spontaneous healing. MATERIALS AND METHODS: In a total of 18 patients, tooth extraction in posterior sites of the upper and lower jaw was performed in a split-mouth design. The post-extraction sockets were randomly assigned to the following two treatment modalities: deproteinized bovine bone mineral (DBBM) with 10% collagen (DBBM-C) covered with a native bilayer collagen membrane (NBCM) (test group) and spontaneous healing (control group). Cone beam computed tomography (CBCT) scans were performed after extractions, 3 and 6 months later. The following parameters were measured: the height of the buccal bone plate (BH), height of the palatal bone plate (PH), horizontal width of the extraction socket at 1 mm, 3 mm, and 5 mm (HW-1, HW-3, HW-5), and the horizontal width (thickness) of the buccal bone plate at 1 mm, 3 mm, and 5 mm (BHP-1, BHP-3, BHP-5). Statistical analysis was performed applying a nonparametric Wilcoxon signed-rank test. RESULTS: The CBCT analysis showed a bone loss compared to baseline in test and control group. The measurements which have reached statistically significant differences at 6 months were BH (test: -2.31% vs control: -13.11%), PH (test: -2.07% vs control: -15.32%), HW-1 (test: -17.14% vs control: -32.47%), and HW-3 (test: -11.65% vs control: -28.47%). CONCLUSIONS: The posterior ridge preservation technique using DBBM-C covered with a NBCM is a valid approach reducing the amount of the radiographic loss in alveolar ridge dimensions.

[A novel technique to preserve the alveolar ridge width following tooth extraction in the maxillary frontal area].

OBJECTIVE: To introduce a novel ridge preservation technique with micro-titanium plate avoiding the use of bone grafting materials, and evaluate the potential horizontal bone preservation effect of this new technique, applied on single maxillary central incisors after tooth extraction for future implant restoration. METHODS: Nine patients (six women and three men), mean age (26.0 ± 5.7) years(from 18 to 34 years) referred to the Department of Oral Implantology, Peking University School and Hospital of Stomotology, were selected and diagnosed with unsalvageable single middle incisor with fine general conditions, no signs of acute local inflammation, no ongoing or previous periodontitis, healthy neighboring teeth and intact buccal bone walls. Tooth extraction, delayed implant placement and implant-supported single crown restoration were selected as treatment plan. The teeth were extracted atraumatically with local anesthesia, followed by a reflection of a minor flap to exposed 2-3 mm of the buccal bone plate. After that, a micro-titanium plate was trimmed and bended to fit the convexity of the labial bone and fixed by two mini pins with intent to support the labial soft tissue. The flap was then repositioned over the micro titanium plate and secured with two single sutures. No bone grafting materials or releasing incisions were needed. The sockets were left to heal without any intention of primary wound closure. Cone-beam computed tomographic (CBCT) scans were obtained before and four months after tooth extraction. Horizontal ridge widths were measured with CBCT software, and the preservation effects were calculated and recorded by the percentage of horizontal ridge alteration. RESULTS: The nine extraction sockets were healed uneventfully. The average socket width before extraction was (7.51 ± 0.48) mm (6.92-7.82 mm). The average alveolar ridge labial-palatal width at the control point of the edentulous area was (6.81±0.44) mm (6.04-7.38 mm) 4 months after tooth extraction, the mean percentage of ridge width preserved was 90.87% ± 2.91% (87.28%-95.60%). CONCLUSION: This novel ridge preservation method by the usage of a micro-titanium plate did not interfere with the natural socket healing process, and at the same time, largely preserved the width of alveolar ridge without any bone grafting procedures. Long term results remain to be seen.

[Computer-assisted implant restoration of free-end partially edentulous mandible with severe vertical bone deficiency].

OBJECTIVE: To evaluate the applicability, accuracy and clinical outcome of the computer assisted design and computer assisted manufacture (CAD & CAM) tooth-supported implant surgical guide in the mandibular free-end partially edentulous patients with insufficient vertical bone height. METHODS: According to the inclusion criteria, 3 patients (2 women, and 1 man) with the mean age of 45 years (from 44 to 46 years) with 10 implant sites were involved in this study. With the help of Computer-assisted-design software to plan and simulate the surgical strategies, the implant surgical guides were fabricated via the rapid prototyping technique, then the guided implant placement was implemented, finally the post-surgical evaluations were accomplished by the clinical and radiographic examinations. RESULTS: Ten implants were placed in 3 mandibles via the surgical guides, and the implant supported non-split restorations were in place. All the implant restorations revealed good clinical function until the last review. No inferior alveolar nerve injury was detected by the clinical neurosensory test. The immediate post surgical CBCT was performed to confirm a safe distance of 1.5 to 3.0 mm between the implant apical and the nerve canal. The deviations between the planed and the actually placed implant were: coronal deviation (0.84±0.30) mm (0.31-1.24 mm); apical deviation (1.42±0.52) mm (0.52-2.36 mm); angular deviation 7.65°±1.84° (4.43°-9.81°). CONCLUSION: In case of distal free-end partially edentulous with insufficient vertical bone height in the posterior mandibular region, computer assisted surgical design and guided surgery can offer a treatment option with minimal invasiveness and a shorter treatment period, and avoid the complicated bone augmentation procedure and the high risk of nerve transposition. This technique is clinically and technically feasible, but the cases using this technique should be strictly selected according to the indication.

[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.

[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.

Minimally Invasive Crestal Sinus Lift Technique and Simultaneous Implant Placement.

OBJECTIVE: To evaluate the effectiveness and clinical results of a new crestal sinus lift technique used to elevate the sinus floor simultaneously with bone grafts and implant placement. METHODS: Eleven patients underwent this crestal sinus lift technique performed using an SCA KIT. The mean residual bone height was 6.4 mm (range: 4.1 mm to 8.6 mm). Bio-Oss collagen was used as the graft material, and 12 implants were simultaneously placed after sinus augmentation. Radiographic and clinical examinations were conducted during follow-up. RESULTS: All procedures were successfully performed with no obvious Schneiderian membrane perforation. The sinus floor was augmented with a mean height of 4.8 mm (range: 2.8 to 7.4 mm). Twelve implants healed uneventfully with healing abutments. Peri-implant marginal bone was stable, with a mean follow-up of 49.4 months (range: 33 to 71 months). No complications were observed during follow-up. CONCLUSION: According to the limited data collected in this study, the novel crestal sinus lift approach could effectively lift the sinus floor and reduce the incidence of postoperative complications. Additional cases with long-term follow-up are needed to confirm and improve this crestal sinus lift technique.

[A minimally invasive extraction technique using Benex Extraction System in flapless immediate implant placement in anterior teeth].

PURPOSE: To evaluate the feasibility and clinical outcomes of an atraumatic extraction technique using Benex Extraction System in flapless immediate implant placement in anterior teeth. METHODS: Twenty-five patients with single hopeless anterior maxillary teeth were enrolled in the study. The involved teeth were extracted using Benex Extraction System and implants were immediately placed in a flapless way. Healing abutments were connected immediately. After 4-6 months of healing, screw-retained implant temporary crowns were used to reshape the peri-implant gingiva. Permanent restorations were delivered 3 months later. Extraction time was recorded and the technique feasibility was evaluated using visual analogue scale (VAS). Peri-implant marginal bone resorption was measured in X- ray films after loading for 1 year later. Pink esthetic score (PES) was checked to evaluate the gingival esthetics. Questionnaire was delivered and collected to assess patients' satisfaction on surgical experience and esthetic outcomes. SPSS 13.0 software package was used for statistical analysis. RESULTS: Twenty-five implants osseointegrated successfully. The marginal bone resorption was (0.21±0.23) mm and PES was 8.8±1.19 after loading for 1 year. The mean extraction time was 6.87 minutes and the VAS was 3.32. All patients were satisfied with the final esthetic outcomes and felt comfort during surgery. CONCLUSIONS: According to the limited data in the study, Benex extraction System is a convenient, atraumatic and predictable technique during flapless immediate implant placement in anterior teeth.

A New Technique for Minimally Invasive Maxillary Lateral Sinus Augmentation: a Case Report.

Numerous techniques are described for lateral sinus augmentation, in order to expand bone volume, either by a crestal or lateral approach. A successful surgical procedure is determined by a number of factors. It is reported that different techniques for sinus augmentation have a high percentage of success, but presents a number of intraoperative and postoperative complications such as the Schneiderian membrane perforation and a long operating time. To manage the problem of the insufficient bone height in the posterior maxilla, various bonegrafting materials were applied using different techniques and instruments to elevate the sinus membrane and fill the subsinus cavity thereafter. The article aimed to describe a minimally invasive technique, using a special design bur to wear out the lateral bone safely and elevate the sinus membrane with sophisticated separators. Platelet-rich fibrin (PRF) and decalcified bone allograft was used as grafting material to enhance bone healing. This new technique for the sinus lateral wall osteotomy minimised the incidence of intraoperative and postoperative complications and the mixed use of PRF with decalcified bone allograft showing a satisficatory efficacy.

[Normal occlusion study: using T-Scan III occlusal analysis system].

OBJECTIVE: To investigate the normal occlusal force distribution and the characteristics of the occlusion time at different occlusion position using T-Scan III occlusal analysis system. METHODS: Fifty-three volunteers with normal occlusion, including 29 males and 24 females, were included in this study. The average age was (25.9 ± 2.1) years old. T-Scan III occlusal analysis system was used to measure the occlusal force distribution and the time character of normal occlusion at intercuspal position, protrusive position, and lateral excursive position. RESULTS: At intercuspal position the left and right side molar teeth took the most part of force percentage, followed by (13.3 ± 4.3)%, (13.6 ± 5.4)%, (15.7 ± 7.1)%, (18.7 ± 7.5)% (6, 6, 7, 7); and 7654, 4567 took (61.3 ± 12.4)% force percentage; and the left and right sides took the respective percentages of (46.4 ± 7.0)%, (53.6 ± 7.0)%, the left side was significantly less than the right side(P < 0.05). At the protrusion position the region ( 21, 12) commitment to take the percentage of (85.1 ± 25.5)%. At left and right lateral position, 28% (13/46) and 30%(14/46) were cuspid-protected occlusion, and 33%(15/46) and 44%(20/46) were group functional occlusion, and 39%(18/46) and 26%(12/46) were multiple-protected occlusion. The average occlusion time was (0.34 ± 0.11) s, and disclusion time was (1.00 ± 0.39) s. CONCLUSIONS: At intercuspal position the region from first premolar to second molar teeth were the occlusal force centers, and the second molar is the most;.the force concentrated in the area ( 21, 12) at the protrusion position. The lateral occlusal pattern is multiformity.

[Measurement and analysis of smile line of 62 Han-Chinese].

OBJECTIVE: To analyze smile features in maximum lip-dynamic in Chinese. METHODS: Sixty-two Han-Chinese, travelling in Germany, with a mean age of 28.5 years were enrolled and photographed. Standardized digital photos were made to measure the height of displayed maxillary gingiva, papilla and tooth during an enjoyment smile. Statistical analysis was performed using Mann-Whitney-U Test and non-parametric analysis. RESULTS: The mean height of tooth display for the central incisors was 10 mm, with no significant difference between the gender (P > 0.05). The mean height of gingival display was 1.3 mm and the mean papilla height was 3.4 mm. There was no significant difference between the genders (P > 0.05). 31% (19/62) of the subjects belonged to high smile line type, 50% (31/62) to medium smile line type and 19% (12/62) to low smile line type. CONCLUSIONS: The red esthetics is a paramount factor for Chinese men and women in the esthetic restoration. 81% of the Chinese studied showed various degree of gingival exposure from central incisor to the premolars, which defined the esthetic area for Chinese people. Papilla is a critical parameter for esthetic evaluation and treatment design. The ratio of high smile line in Chinese may be higher than that in Caucasian.

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.

[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.

[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.

[Clinical study of sinus elevation by water balloon and implant placement].

OBJECTIVE: To evaluate the clinical results and technique of minimally invasive sinus membrane water balloon elevation followed by bone augmentation and implant placement simultaneously. METHODS: From May 2006 to November 2007, 31 patients (male: 16, female: 15; mean age: 41.2 +/- 11.8) were involved in the study. Clinical examination and radiographs were conducted. RESULTS: The mean residual ridge height was (4.79 +/- 1.18) mm and the mean elevated height was (10.60 +/- 2.06) mm. A total of 31 implants were placed and restored with the mean follow-up period of (14.2 +/- 3.6) months. Only minor complications were observed postoperatively. One implant was lost due to infection two weeks after operation. CONCLUSIONS: The procedure of minimally invasive sinus membrane water balloon elevation achieves an excellent success rate, low complication, minimal discomfort, and the short-term result is predictable.

[A clinical retrospective study of 10 years implant results].

OBJECTIVE: To evaluate ten years clinical results of dental implant treatment. METHODS: A total of 5,590 endosseous implants were consecutively placed from Aug. 1994 to Aug 2004 in Center of Implantation, Peking University School and Hospital of Stomatology. Among them, 161 were Brånemark implants, 1,436 were Frialit-2 implants, 1,012 were IMZ implants, 767 were Ankylos implants, 2,189 were Camlog implants, and 25 were Komet implants. A total of 2,629 prostheses were delivered, including 2,314 fixed prostheses and 315 implant-supported removable dentures. The patient age range was between 17 and 82. The mean follow-up time was 77.2 months (7 to 121 months). Clinical examination and X-ray films were conducted. The results were evaluated with Wheeler's survival criteria. RESULTS: With the final prostheses, 2,624 patients were satisfied. Five patients were unsatisfied with the prostheses. With refabricating the prostheses, 4 patients were satisfied and one expressed as acceptable. Peri-implantitis was observed in 178 implants of 105 cases. Prostheses loose was observed in 21 cases and fracture in 4 cases. Ceramic crack was observed in 51 cases. The documented implants lost were 68. The implant survival rate was 96.7% according to Wheeler's survival criteria. CONCLUSIONS: Implant prostheses were with high satisfaction. The implant survival rate was as highly as 96.7%. Implant prostheses were indicated for almost all the partial and complete edentulous cases due to modern implant surgical technique.