A customized metal guide for controllable modification of anterior teeth contour prior to minimally invasive preparation

ObjectiveOptimal tooth reduction is a key requirement for aesthetics, function, and the longevity of fixed restorations. Research has demonstrated that controlled and conservative tooth preparation is crucial for the long-term success of adhesive restorations. Different techniques of fabricating reduction guides have been previously reported in literature. The present technical note describes the fabrication technique and clinical application of a customized metal preparation reduction guide.Material and methodPatient presented with tilted maxillary left central incisor. The flared-out part of the tooth was modified prior to veneer restoration preparation. Resin pattern reduction guide was fabricated on the diagnostic cast with a window on the tilted mesial portion of the tooth. After intraoral evaluation, resin pattern guide was casted. Metal reduction guide was place intraorally and reduction was provided on the exposed surface of the tooth. After the removal of the tilted portion, a harmonious arch form allowed the clinician to provide adequate evaluation and preparation for veneer restorations.ResultsThe device demonstrated good practical value, allowing for selective and controlled reduction of tooth structure, and definitive protection of adjacent tooth surfaces from iatrogenic damage. The clinical outcome successfully addressed the patient’s restorative and aesthetic needs, and the veneer was stable 2 years postoperatively.ConclusionUse of a metal guide assists clinicians to provide a more predictable reduction of a desired tooth surface, while decreasing the risk of compromising the other/adjacent tooth surfaces.     

Influence of coping and veneer thickness on the color of zirconia-based restorations on different implant abutment backgrounds

Statement of problem

The effects of coping and veneer thickness on the color of zirconia-based restorations are unknown.

Optimal number of implants for complete-arch implant-supported prostheses with a follow-up of at least 5 years: A systematic review and meta-analysis

Statement of problem

Consensus is lacking regarding the optimal number of implants for supporting complete-arch prostheses with good survival rates and lower prosthetic complications and marginal bone loss.

牙颌组织及修复体三维几何学、有限元模型的设计

目的 建立口腔修复各类模型及模型库系统。方法 以正常颌骨及牙弓为样本，在CT技术及计算机软件（PRO／E，ANSYS等的）的帮助下，首先建立部分上颌骨及下颌骨的三维几何学模型和有限元模型，再建立牙颌组织和修复体的各类模型库，最后探讨模型和模型库的应用方法。结果 建立了部分上颌骨，下颌骨，牙列及修复体的三维模型及模型库。结论 模型具有较好的力学相似形和几何学相似形，模型库应用高效方便。     

Removal torque and force to failure of non-axially tightened implant abutment screws

Statement of problem

Components have been introduced that allow the screw channel of an implant crown to be angled lingually and the screws to be tightened in a non-axial direction to the implant. Information is lacking as to how the removal torque value (RTV) and force to failure (FTF) of these components compare with those of conventional screws.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: Marginal and internal fit

Statement of problem

Trials comparing the overall performances of digital and conventional workflows in restorative dentistry are lacking.

A Randomised Controlled Trial of complete denture impression materials

Objectives

There is continuing demand for non-implant prosthodontic treatment and yet there is a paucity of high quality Randomised Controlled Trial (RCT) evidence for best practice. The aim of this research was to provide evidence for best practice in prosthodontic impressions by comparing two impression materials in a double-blind, randomised, crossover, controlled, clinical trial.

Methods

Eighty-five patients were recruited, using published eligibility criteria, to the trial at Leeds Dental Institute, UK. Each patient received two sets of dentures; made using either alginate or silicone impressions. Randomisations determined the order of assessment and order of impressions. The primary outcome was patient blinded preference for unadjusted dentures. Secondary outcomes were patient preference for the adjusted dentures, rating of comfort, stability and chewing efficiency, experience of each impression, and an OHIP-EDENT questionnaire.

Results

Seventy-eight (91.8%) patients completed the primary assessment. 53(67.9%) patients preferred dentures made from silicone impressions while 14(17.9%) preferred alginate impressions. 4(5.1%) patients found both dentures equally satisfactory and 7 (9.0%) found both equally unsatisfactory. There was a 50% difference in preference rates (in favour of silicone) (95%CI 32.7–67.3%, p < 0.0001).

Conclusion

There is significant evidence that dentures made from silicone impressions were preferred by patients.

Clinical significance

Given the strength of the clinical findings within this paper, dentists should consider choosing silicone rather than alginate as their material of choice for secondary impressions for complete dentures.Trial Registration: ISRCTN 01528038.This article forms part of a project for which the author (TPH) won the Senior Clinical Unilever Hatton Award of the International Assocation for Dental Research, Capetown, South Africa, June 2014.     

Thickness and marking quality of different occlusal contact registration strips

Objectives

Evaluate the thickness and the marking quality of different occlusal contact registration strips (OCRS) and a possible correlation between them.

Material and Methods

The following OCRS were selected: Accufilm II, BK20, BK21, BK22, BK23, BK28, and BK31. The thickness was measured in three points of the OCRS with an electronic measuring device (TESA), and the mean was calculated. To produce the marks on the strips, composite resin specimens were adapted to a universal testing machine (Versat 2000) with 40 kgf load cell at a speed of 1.0 mm/min. The mark images were photographed with a stereoscopic microscope (Stemi SV11) and processed and analyzed by the 550-Leica Qwin^® analyzer.

Results

Values (μm) found in the 1^st and 2^nd thickness measurements were: Accufilm II - 16.4 and 14.2; BK20 - 10.0 and 8.1; BK21 - 9.5 and 8.0; BK22 - 9.7 and 8.7; BK23 - 9.8 and 7.9; BK28 - 12.8 and 10.0; and BK31 - 8.4 and 8.0, respectively. The mean (mm²) values found in the mark areas were: Accufilm II - 0.078; BK20 - 0.035; BK21 - 0.045; BK22 - 0.012; BK23 - 0.022; BK28 - 0.024; and BK31 - 0.024. The results were submitted to the Kruskal-Wallis (p<0.05) and Pearson’s correlation tests.

Conclusions

Only in the 2^nd measurement, the OCRS thickness observed was similar to the value indicated by the manufacturers; the Accufilm II and the BK28 strips showed the better marks; and no correlation was found between the thickness and the marking area.     

GLTC医患沟通模式结合病例导入式教学在口腔修复实践教学中的应用研究

目的　探究GLTC[示善（goodwill）、倾听（listening）、交流（talking）、合作（cooperation）]医患沟通模式结合病例导入式教学在口腔修复实践教学中的应用研究。方法　选取2019年7月至2020年7月在四川大学华西口腔医院实习的30名口腔医学本科实习生,按照简单随机数字表法分为对照组（n=15）和观察组（n=15）。对照组采用病例导入式教学,观察组采用GLTC医患沟通模式结合病例导入式教学。评估两组实习生的临床实习成绩（理论成绩、病历分析成绩、操作成绩、讲课成绩）、实习生进行医患沟通的能力、实习生教学主观评价。采用SPSS 22.0软件进行t检验和卡方检验。结果　观察组实习生的理论成绩、病历分析成绩、操作成绩、讲课成绩均优于对照组（P<0.05）;观察组实习生的利物浦医生沟通能力评价量表评分高于对照组（P<0.05）;观察组实习生教学模式主观评价中提高学习兴趣、集体意识、语言表达能力、综合分析能力、临床操作能力均优于对照组（P<0.05）。结论　将GLTC医患沟通模式结合病例导入式教学法应用在口腔修复实践教学中效果明显,能有效提升实习生的专业知识和技能,提高教学满意度及医患沟通能力。     

二氧化锆修复体与镍铬合金在口腔修复中的修复效能比较

目的 比较二氧化锆修复体与镍铬合金在口腔修复中的修复效能。方法 回顾性分析2020年6月至2021年6月于杭州口腔医院接受口腔修复治疗的98例患者临床资料,根据修复体材料不同分为二氧化锆组50例,镍铬合金组48例。比较两组患者的修复效果及修复前后的咬合力、咀嚼效率,并比较两组患者修复前后的菌斑指数（plaque index,PLI）、牙龈指数（gingival index,GI）、龈沟出血指数（sulcus bleeding index,SBI）和肿瘤坏死因子–α（tumor necrosis factor–α,TNF–α）、白细胞介素–6（interleukin–6,IL–6）水平,评估两组患者修复后修复体折断和崩瓷情况。结果 二氧化锆组修复优良率高于镍铬合金组（P<0.05）。修复后两组患者的咬合力、咀嚼效率高于修复前（P<0.05）,且二氧化锆组咬合力和咀嚼效率均高于镍铬合金组（P<0.05）。修复后二氧化锆组和镍铬合金组PLI、GI、SBI较修复前降低（P<0.05）,且二氧化锆组PLI、G、SBI低于镍铬合金组（P<0.05）。修复后两组TNF–α、IL–6较修复前均升高（P<0.05）,但修复后二氧化锆组TNF–α、IL–6水平低于镍铬合金组（P<0.05）。二氧化锆组未出现一例修复体折断和崩瓷,镍铬合金组出现3例修复体折断、2例修复体崩瓷。结论 口腔修复患者应用二氧化锆修复体可促进咬合能力和咀嚼功能恢复,缓解龈沟液炎性反应,值得临床广泛推广和应用。