"Influence of the interforaminal arch form of edentulous mandibles on design of ""All-on-4"":preliminary research based on conebeam computed tomography" / 北京大学学报(医学版)

Objective:To classify the interforaminal arch form of edentulous mandibles by measuring the anterior-posterior distance (A-P distance) of implants planned to be inserted in All-on-4 protocol using conebeam computed tomography (CBCT) data, and to investigate the influence of the arch form on the All-on-4 distally tilted implants.Methods: Seventy-four CBCT images of edentulous mandibles were collected, including 35 males and 39 females respectively.All-on-4implant supported fixed prostheses were designed for these patients based on the CBCT data.The A-P distance was measured in the plane which crossed bilateral mental foramens and was parallel to the occlusal plane.The interforaminal arch form of edentulous mandibles were classified according to the A-P distance.The radian of the jaw arch 7.5 mm mesially to the mental foramen was measured bilaterally, and its correlation with the A-P distance was studied.Results: The average A-P distance of implant supported fixed prostheses planned in the interforaminal region was (8.5±1.5) mm (minimum 4.5 mm, maximum 11.8 mm).In the study, 12.2% of the subjects'' mandibles were classified as square arch form with A-P distances ≤7 mm, 54.0% were classified as ovoid with A-P distances >7 mm and ≤9 mm, 33.8% were classified as tapered with A-P distances >9 mm.Bilaterally, 148 results of the radian of the jaw arch 7.5 mm mesially to the mental foramen were obtained, and the average radian was 15.9°±5.5° (minimum 5.6°, maximum 35.2°).The radian and the A-P distance showed a negative correlation with statistical significance.Conclusion: In this research, the ovoid arch form was the most common type in edentulous mandibles, followed by tapered arch form.The square arch form showed the lowest percentage.As the arch form went squarer, the A-P distance became shorter, the radian of the jaw arch mesially to the mental foramen went greater, and the bone width that distally tilted implants need became bigger.The interforaminal arch form of the edentulous mandible should be analyzed before an implant supported fixed restoration is designed in the interforaminal region.The angle of inclination of distal implants should be reasonable.The bone width of the distal implant site must be adequate.The square arch form contributes negatively to the structure of implant supported fixed prostheses with distal cantilever design.

Distribution and content of transforming growth factor-β1 and vascular endothelial growth factor in each layer of concentrated growth factors / 北京大学学报(医学版)

Objective:To investigate the distribution and content of transforming growth factor-β1 (TGF-β1)and vascular endothelial growth factor (VEGF)in concentrated growth factors (CGF)gel, and to clarify the difference among different layers of CGF.Methods:Venous blood samples were col-lected from 6 healthy volunteers to prepare CGF.The distribution,integrated optical density (IOD)and average optical density (AOD)of TGF-β1 and VEGF in CGF gel and red blood cell (RBC)layer were measured using immunohistochemistry.The concentrations of TGF-β1 and VEGF in the supernatant se-rum at baseline and the CGF releasate after 1 day were evaluated with enzyme-linked immunosorbent as-says.Results:Abundant TGF-β1 and VEGF were concentrated in CGF gel.However,only a little could be found in polykaryocytes and sporadic platelets in RBC layer.Platelets and leukocytes were concentra-ted in between the two layers with high expression of TGF-β1.The concentrations of TGF-β1 and VEGF in the CGF releasate(55 236.78 ±3 686.34),(610.99 ±148.81)ng/L were significantly higher than those in the supernatant serum (20 710.20 ±4 523.14),(335.20 ±51.69 )ng/L (P <0.001 ). Conclusion:CGF contains high quantities of TGF-β1 that can promote new bone formation and tissue healing.We suggest that CGF gel should be used right after being prepared.Supernatant serum and the area between CGF gel and RBC layer could also be mixed with bone substitute materials.

Technical complications rates and plaque control of fixed dental prostheses in patients treated for periodontal disease / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare the incidence of technical complications of implant-supported fixed dental prostheses in Chinese patients with a history of moderate or severe periodontitis and periodontally healthy patients(PHP) and analyze the effects of interproximal papillae patterns on food impaction and efficacy of plaque control.</p><p><b>METHODS</b>A total of 103 partially edentulous patients treated with implant-supported fixed dental prostheses between December 2009 and December 2012 for a minimum 1-year follow-up period were recruited from Department of Periodontology, Peking University, School and Hospital of Stomatology. Based on the initial periodontal examination, the participants were divided into three groups: 30 PHP, 36 moderate periodontally compromised patients(mPCP) and 37 severe periodontally compromised patients(sPCP). Implant survival/loss, technical complications, plaque index, papilla index, food impaction and degree of proximal contact tightness of each patient were assessed around the implants at follow-up. According to the implant papilla index, the implants were divided into two groups: the "filling" group with the mesial and distal aspects with papilla index=3 and the "no filling" group with at least one aspect with papilla index<3. Data on implant survival, technical complications were analyzed. Comparisons of the incidence of technical complications were performed between the patients with different periodontal conditions with chi-square or Fisher's exact test. The influences of the interproximal papillae loss on food impaction and efficacy of plaque control were estimated with chi-square and Mann-Whitney U tests.</p><p><b>RESULTS</b>The total implant survival rate was 100%(162/162) for all three groups. Technical complications were as following: veneer fractures(1.9%, 3/162), abutment screw loosening(1.9%, 3/162), prosthetic screw loosening(3.1%, 5/162) and decementation(3.1%, 5/162) in all subjects. No implant/screw fracture was noted. The incidence of technical complications in sPCP, mPCP and PHP did not yield statistically significant differences(P>0.05). The proportion of the implant with the mesial and distal papilla index=3 in the sPCP was less than that in the PHP and mPCP. The interproximal papillae loss did not appear to affect the food impaction and the plaque index in all three groups(P>0.05). However, for the PHP, the accumulation of plaque at buccal aspect was more in the "no filling" group compared with the "filling" group (implant plaque index[M(Q)]: 1[1] vs 0[0]), and for the sPCP, the accumulation of plaque at lingual aspect was more in the "filling" group compared with the "no filling" group(implant plaque index[M(Q)]: 1[1] vs 0[1], (P<0.05).</p><p><b>CONCLUSIONS</b>The patients with a history of severe periodontitis did not exhibit more technical problems compared with the periodontally healthy patients. The interproximal papillae loss did not show a negative impact on the plaque control and food impaction. However, for the sPCP, changing the morphology and the position of the interproximal contact point to reduce the interdental black triangle may lead to accumulation of plaque at lingual aspect. More attention should be placed on the morphology design of prosthesis, but not the papillae filling up the interproximal space.</p>

Multi-source data acquisition technology in the restoration of the complete denture restoration / 中华口腔医学杂志

In complete-denture restoration of edentulous jaws, the following information is needed: functional impression of edentulous jaws, jaw relationship and facial fullness, parameters of individual mandibular movement, etc. Traditional clinical methods in obtaining these data, which depend greatly on practitioners' clinical experience and skills, are subjective, complicated and low efficient. With the development of the digital restoration of edentulous jaws, a variety of equipment for three-dimensional scan have been applied in acquiring three-dimensional source data concerning the needed information, which greatly simplifies the process of data obtaining, reduces the dependence on operational skills and subjective experience, improves efficiency and efficacy of diagnosis and treatment, and standardizes the restoration process.

Evaluation of clinical application of ACP classification for edentulous patients / 北京大学学报(医学版)

Objective:To evaluate clinical application of American College of Prosthodontics classification system for complete edentulism;and to analyze the relationship between clinician's rating of general degree of difficulty of each case and patients' rating of denture satisfaction.Methods:One hundred and seven edentulous patients were examined clinically using American College of Prosthodontics(ACP) classification for complete edentulism.The least heights of patients' mandible were measured on panoramic radiographs.Clinician rated general degree of difficulty of each case on visual analogue scale.Six month following denture delivery,patients rated their denture using Mcgill satisfaction Visual Analog Scale(VAS).Multivariate linear regression analysis were conducted to analyze the relationship between clinican's rating of general degree of difficulty and mandibular bone height adjusting for confounding factors such as mandibular ridge form,soft tissue quality etc.Pearson correlation analysis was conducted to analyze the correlation between clinician's rating of case difficulty and patients' rating of denture satisfaction.Results: Advanced residual ridge resorption were found in around 80%(83/105) of all the cases.When the least mandibular bone height were measured on panoramic radiographs,intra-examiner reliability was 0.96,inter-examiner reliability was 0.90.Cases were rated as more difficult when patients showed lower mandibular bone height,unfavoriate ridge form(knife ridge and irregular ridge),mobile soft tissue and longer period of wearing time of their previous dentures.No significant correlation(r