[Clinical evaluation of "All-on-Four" provisional prostheses reinforced with carbon fibers].

OBJECTIVE: To assess the clinical effects of carbon fiber reinforcement on the "All-on-Four" provisional prostheses. METHODS: Provisional prostheses were divided into control group and carbon fiber reinforcing group according to whether carbon fiber reinforcement was used in the provisional prostheses base resin. In our study, a total of 60 patients (32 males and 28 females) with 71 provisional prostheses(28 maxilla and 43 mandible)were enrolled between April 2008 and December 2012 for control group; a total of 23 patients (13 males and 10 females) with 28 provisional prostheses (9 maxillas and 19 mandibles) were enrolled between January 2013 and March 2014 for carbon fiber reinforcing group. The information of provisional prostheses in the patients was recorded according to preoperative examination. We used the date of definitive prosthesis restoration as the cut-off point, observing whether fracture occurred on the provisional prostheses in the two groups. Additionally we observed whether fiber exposure occurred on the tissue surface of the provisional prostheses and caused mucosal irritation. The interface between the denture base resin and the fibers was examined using scanning electron microscopy (SEM). RESULTS: The age [(57.3 ± 10.1) years vs.(55.1 ± 11.4) years], gender (32 males and 28 females vs. 13 males and 10 females), maxilla and mandible distributions (28 maxillas and 43 mandibles vs. 9 maxillas and 19 mandibles), the number of extraction jaws (46 vs. 23), the average using time [(7.8 ± 1.3) months vs. (7.5 ± 1.1) months], and the opposing dentition distributions of provisional prostheses of the patients showed no significant differences between the control and reinforcing groups. There were 21(29.6%) fractures that occurred on the 71 provisional prostheses in the control group; there was no fracture that occurred on the 28 provisional prosthesesin the carbon fiber reinforcing group. The fracture rate of the carbon fiber reinforcing group was significantly lower than that of the control group (P=0.001). No carbon fiber exposure and mucosal irritation were observed from clinical examination.SEM revealed relatively continuous contact between the fiber and acrylic resin, and the resin particles adhered on the surface of the carbon fibers. CONCLUSION: The addition of carbon fibers between abutments placed on "All-on-Four" provisional fixed denture base resin may be clinically effective in preventing "All-on-Four" denture fracture and can provide several advantages for clinical use.

[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.

[Effect of provisional restoration on shaping the contour of the soft tissue during maxillary single tooth implant procedure].

OBJECTIVE: To evaluate the influence of soft tissue aesthetic outcomes following application of adhensive fixed partial denture and implant supported temporary restoration in maxillary single tooth implant procedure. Discuss the feasibility and details of the shaping the soft tissue by combine adhensive fixed partial denture and implant-supported temporary restoration. METHODS: The study included 29 patients(Male: 17, Female: 12) with hopeless maxillary single tooth from Sept. 2008 to Dec. 2010. All patients received tooth extraction and implant treatment in department of oral implantology, Peking University School and hospital of Stomatology. The adhesive fixed partial denture as a provisional restoration was used to support the soft tissue of the tooth extraction socket after tooth extraction. The average time of patient wearing adhensive fixed partial denture was 3.7 months. The implant supported temporary restoration was delivered to shape the soft tissue after implant placement. The average time of implant supported provisional restoration using was 8.3 months. Soft tissue esthetic condition was evaluated through 4 main index reference pink esthetic score (PES) before tooth extraction and at the time of the final restoration. Clinical observe items also included the survival rate of fixed partial denture and rate of re-adhesive, integrity of temporary restoration and degree of satisfaction of the patients. The control group included 29 cases with removable denture or without temporary restoration. The base line differences between control group and experiment group were not statistically significant. RESULTS: The survival rate of both the adhensive partial denture and implant-supported provisional restoration was 100%. The re-adhesive rate of adhesive partial denture was 16.2% during follow-up period. The PES at the time of final restoration were significant different between two groups by t test (7.48±0.51 vs. 5.69±0.71, P<0.000 1). Patients were satisfied with the clinical results. CONCLUSION: This study indicates that fixed partial restoration and implant-supported provisional restoration could be used to support and to shape the soft tissue contour and to improve the aesthetic effects.

[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.

Effects of different mulching modes on soil nitrate concentration and grain yield of Linum usitatissimum in dry land.

To investigate soil NO3--N dynamics and yield increasing effect of mulching planting for Linum usitatissimum (oil flax) in semi-arid Loess Plateau, we examined the effects of three mul-ching modes (whole field plastic mulching and micro ridges with soil cover and bunch-seeding; whole field plastic mulching with soil cover and bunch-seeding; and straw mulching with strips) on seed yield and distribution of soil NO3--N during the main growth periods of oil flax, with the conventional planting model as control (CK) in 2015 and 2016. Results showed that the average yield under mulching modes was increased by 56.1% (2015) and 22.7% (2016). The treatment of whole field plastic mulching with soil cover and bunch-seeding had the highest grain yield. Mulching treatments significantly increased soil water content. Soil water content was increased first and then reduced in the whole growth stage of oil flax. The soil NO3--N content was gradually decreased during the oil flax growth process. In both years, NO3--N content in 0-40 cm soil depth under mul-ching treatments were increased by 3.1%-18.6% (2015) and 5.1%-16.4% (2016) at budding stage of oil flax, respectively. The whole field plastic mulching with soil cover and bunch-seeding treatment showed the larges increases across all treatments. In 2015, NO3--N accumulation in 0-100 cm soil depth between the flowering and maturity stages of oil flax were increased by 10.2%-22.2% and 8.6%-21.4%, respectively. Especially during the more rainfall period of maturity stage, NO3--N accumulation in 0-40 cm soil depth was significantly enhanced by 3.3%-4.9% than that in 40-100 cm soil depth. It indicated that more rainfall could slow down the migration of NO3--N to the lower layer under the mulching modes in the maturity stage. In 2016, high temperature and drought at late growth stages had a great influence on oil flax growth. The NO3--N accumulation in 0-100 cm soil depth at the maturity stage was increased by 6.6%-18.0%. There was significant correlation between NO3--N content and grain yield during the main growth stages of oil flax. In conclusion, the whole field plastic mulching with soil cover and bunch-seeding treatment was the most appropriate way of oil flax production in arid and semi-arid area.

In vitro evaluation of the flexural properties of All-on-Four provisional fixed denture base resin partially reinforced with fibers.

The aim of this study was to assess the effects of partial carbon or glass fiber reinforcement on the flexural properties of All-on-Four provisional fixed denture base resin. The carbon or glass fibers were woven (3% by weight) together in three strands and twisted and tightened between the two abutments in a figure-of-"8" pattern. Four types of specimens were fabricated for the three-point loading test. The interface between the denture base resin and fibers was examined using scanning electron microscopy (SEM). Reinforcement with carbon or glass fibers between two abutments significantly increased the flexural strength and flexural modulus. SEM revealed relatively continuous contact between the fibers and acrylic resin. The addition of carbon or glass fibers between two abutments placed on All-on-Four provisional fixed denture base resin may be clinically effective in preventing All-on-Four denture fracture and can provide several advantages for clinical use.

[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.

[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.

[Application of implant-supported telescopic overdenture in edentulous cases].

OBJECTIVE: To evaluate clinical results of implant supported telescopic overdenture. METHODS: 21 patients with edentulous jaws underwent telescopic overdenture restoration. A total of 28 prostheses were fabricated. Of them, 13 were in the upper jaws, 15 in the lower jaws. Among 139 placed implants, 74 were Camcog, 28 IMZ, and 37 Frialit-2. The secondary crown was fabricated by electroforming technique and wax-lost cast method. Clinical examination and radiographs were conducted. Changes in the marginal bone level around the implants were evaluated with radiograph. The mean follow-up time was 26.5 months (range 12 - 39 months). RESULTS: This type of restoration could provide sufficient stability and maintain peri-implant hygiene easily. Peri-implantitis and prosthetic complications were not observed. Marginal bone around implants was stable. No implant was lost during the loading time. CONCLUSIONS: The preliminary clinical results of this research showed that implant supported telescopic overdentures were predictable for edentulous patients.

[Clinical study of implant-retained facial prosthesis].

OBJECTIVE: To evaluate clinical results and technical characteristics of implant-retained facial prosthesis. METHODS: Six patients with facial defects underwent implant retained prosthesis treatment, of which 3 orbita defects (including upper and lower eyelids, eyeball) in 3 cases, 2 ears defects in 2 cases, and a nose defect in one case. Under local anaesthesia 21 extra-oral implant were placed, facial prosthesis were individually made six month postoperatively. Follow up ranged from 6 month to 6 years. RESULTS: All 21 implants osseointegrated well, implant lost and peri implantitis was not found. All 6 cases had individual facial prosthesis and were satisfied with the prosthesis. CONCLUSIONS: Extra oral implants provided excellent retainment for facial prosthesis; result of current silicon with individual color shade is encouragable.