Hawley联合舌侧保持器和压膜式保持器的临床正畸保持效果比较

目的:比较Hawley联合舌侧固定保持器和压膜式保持器的临床效果,为选择合适的正畸保持方式提供参考。方法:选择正畸治疗刚结束的患者45例,随机给下颌戴用压膜式保持器(压膜式保持器组,25例)或联合保持器,即舌侧固定保持器配合夜间Hawley保持器(联合保持器组,20例)。每隔3个月复诊1次,记录矫治前、矫治结束时以及保持6个月和保持1年后的覆、覆盖及牙石指数。在模型上测量下颌牙扭转度、尖牙间和磨牙间宽度以及下前牙不齐指数。采用SAS 6.12软件包对数据进行方差分析、卡方检验和Fisher确切检验,比较2组之间的差异。结果:压膜式保持器组各测量项目在矫治后、保持6个月和保持1年后均无显著差异(P>0.05)。联合保持器组除牙石指数在保持6个月和1年后变化显著大于压膜式保持器组外(P<0.05),其余各项指标2组间均无显著差异。1年内的损坏率,压膜式保持器和联合保持器分别是24%和20%,即成功率76%和80%,两者无显著差异。结论:压膜式保持器保持和舌侧固定保持器配合夜间Hawley保持器保持的1年随访效果均良好,但综合考虑患者依从性和保持器的可靠性,后者是较好的保持方式。     

Prevalence of partial edentulism and RPD design in patients treated at College of Dentistry,Imam Abdulrahman Bin Faisal University,Saudi Arabia

This study aimed to investigate the prevalence of partial edentulism, RPD type, design, and components and their frequency of use by patients at the prosthodontic clinics of the College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia. The prepared surveys, laboratory authorization forms, and images of the RPD metal frameworks on casts were used for data collection. Two calibrated investigators studied the digital photographs to identify the Kennedy classification, type of RPD, major connector, clasp assembly, and other details. Data was collected and analyzed statistically. The results showed that the most common class of partial edentulism was Kennedy class I, whereas class IV was the least (p < 0.001). Sixty two percent of fabricated RPDs had metal frameworks, whereas 37.2% were frameless. RPI was the most frequently used clasp assembly (38.9%), a significant finding in Kennedy class I(p < 0.01). The maxillary anteroposterior palatal strap and mandibular lingual plate were the most commonly used major connectors, at 41.2% and 60.8%, respectively. Conclusions: Simple RPD design that accomplishes the treatment objectives as well as proper communication with a well-trained dental technician would promote the success of RPDs.     

改良式热压膜透明联冠保持器与Hawley保持器临床效果对比的Meta分析

目的:比较改良式热压膜透明联冠保持器和Hawley保持器的差异,从而为正畸医生寻找合适的矫治器提供指导。方法:检索ISI Web ofScience、PubMed、Cochrane Library、CNKI、维普、万方等多个数据库,检索时间截止于2019年5月,检索时没有任何语言限制,所有正畸杂志和相关参考文献都被检索,两位作者独立完成文献筛选、数据提取及质量评价;采用软件Stata/MP 14.0进行数据处理;用Cochrane偏倚风险评估工具进行偏倚风险评估。结果:最终1008个对象12篇研究被纳入,对比两种保持器在上、下颌Little指数变化方面,差异有统计学意义;而在尖牙间宽度、磨牙间宽度方面,差异无统计学意义。结论:改良式热压膜透明联冠保持器比Hawley保持器对前牙位置固位效果好,而在尖牙宽度和磨牙宽度方面,效果几乎无差别。     

The effect of thermo-mechanical fatigue on the retentive force and dimensional changes in polyetheretherketone clasps with different thickness and undercut

PURPOSEEsthetic expectations have increased the use of polyetheretherketone (PEEK) clasps as alternatives to Cr-Co in removable partial dentures (RPDs). The objective of this study was to evaluate the retentive force and dimensional change of clasps with different thickness and undercut made from PEEK by the thermo-mechanical fatigue.MATERIALS AND METHODSPEEK clasps (N = 48) with thicknesses of 1 or 1.50 mm and 48 premolar monolithic zirconia crowns with undercuts of 0.25 mm or 0.50 mm were fabricated. Samples are divided into four groups (C1-C4) and were subjected to 7200 thermal aging cycles (at 5 - 55℃). The changes in the retentive force and dimensions of the clasps were measured by micro-stress testing and micro-CT devices from five measurement points (M1 - M5). One-way ANOVA, paired t-test, two-way repeated ANOVA, and post-hoc tests were used to analyze the data (P < .05).RESULTSThe retentive forces of C1, C2, C3, and C4 groups in initial and final test were found to be 4.389-3.388 N, 4.67 - 3.396 N, 5.161 - 4.096 N, 5.459 - 4.141 N, respectively. The effects of retentive force of all PEEK clasps groups were significant decreased. Thermo-mechanical cycles caused significant dimensional changes at points with M2, M4, and M5, and abraded the clasp corners and increased the distance between the ends of the clasp, resulting in reduced retentive forces (P^* = .016, P^* = .042, P < .001, respectively).CONCLUSIONThermo-mechanical aging decreases the retentive forces in PEEK clasps. Increasing the thickness and undercut amount of clasps decreases the amount of dimensional change. The values measured after aging are within the clinically acceptable limits.     

透明保持器对颞肌、咬肌肌电影响的分析研究

透明保持器是目前正畸治疗中所普遍采用的保持装置之一,然而关于透明保持器对颞肌、咬肌肌电变化影响的研究却很少见.本研究的目的是观察透明保持器戴入前后不同状态下颞肌、咬肌肌电的改变情况.根据筛选标准选择健康受试者,记录透明保持器戴入前后不同状态下颞肌、咬肌的肌电值进行统计分析.结果显示透明保持器戴入后下颌休息位及发[s]、[z]时颞肌、咬肌的肌电值均较未戴前明显增高,发[a]时则无显著性差异.     

透明压膜保持器与Hawley保持器对拔牙病例的保持效果比较

目的　比较透明压膜保持器与Hawley保持器对拔牙病例保持的临床效果差异。方法　选取40例儿童患者正畸完成病例,均拔除4个第一前磨牙,正畸治疗完成后随机分为2组,各20例：A组戴用透明压膜保持器,B组戴用Hawley保持器。采集治疗刚结束(T1)及治疗完成1年后(T2)的记存模型,分别进行PAR指数评价,用SPSS 13.0软件对实验数据进行统计分析。结果　治疗完成1年后,两组间牙齿排列的保持效果显著不同(P＜0.05),其余指标未发现显著性差异。结论　对于拔除第一前磨牙的病例,透明压膜保持器在牙齿排列的保持效果上明显优于Hawley保持器。     

固定黏接式保持器和活动可摘保持器对牙周健康的影响

目的:观察固定黏接式保持器对牙周的影响。方法:选择固定正畸结束的患者30例,进行牙周洁刮治,测量牙周指数。随机分成2组,分别戴入固定保持器与活动保持器,于1周、1个月和3个月检测牙龈指数(gingival index,G I),菌斑指数(p laque index,PLI),牙石指数(calcu lus index,C I)。结果:戴入固定黏接式保持器的患者牙周指数明显比活动可摘保持器组升高。结论:固定保持器和活动保持器对牙周健康都有一定影响,但固定保持器的影响更为明显。     

Allergic contact dermatitis from diphenylthiourea in Vulkan heat retainers

11 cases of contact dermatitis from Vulkan heat retainers are reported. The skin eruptions started on days 1-11 after the 1st day of exposure. The clinical picture varied from eczema through urticaria to purpura. In some cases, the symptoms were severe. Patch testing was performed in 10 individuals and all reacted positively to the heat retainer and/or the rubber glue used in the heat retainer. A series of rubber chemicals was patch tested in 7 patients and all showed positive reactions to diphenylthiourea (DPTU), and all but one to ethylene thiourea (ETU). TLC examination revealed a spot with the same RF-value as DPTU in extracts of the adhesive, but no spot corresponding to ETU. There were no indications of impurities in the test preparations of DPTU and ETU. By HPLC, the content of DPTU in the adhesive was determined as 0.6% w/w.     

透明保持器戴入前后髁突位置变化的初步研究

目的初步研究透明保持器戴入前后髁突位置的变化。方法对经过严格筛选的15名健康受试者拍摄透明保持器戴入前后下颌姿势位时的颞下颌关节侧位体层片,并利用计算机技术对关节间隙进行面积测量及线性测量,对测量结果进行统计分析。结果透明保持器戴入后髁突向前下方移位,对logE(P/A)值进行统计分析发现,二者存在显著差异(P<0.01)。两种方法得到了相似的结果。结论透明保持器戴入前后,髁突位置发生了显著变化,髁突从基本中性位前移到前移位。但戴用不同时间后的改变情况有待进一步的研究。     

Orthodontic treatment stability predictors: A retrospective longitudinal study

Objective:To examine medium- to long-term orthodontic treatment stability and its possible association with certain variables.Materials and Methods:In a retrospective longitudinal study of 70 postretention patients, the Peer Assessment Rating (PAR) index was measured at the start (T1) and end (T2) of treatment and between 4 and 10 years afterwards (T3). The stability was considered absolute when the T2 and T3 values were identical and relative when the difference was within the ±5 range.Results:Among the 70 patients, 65.8% were female and 34.2% were male. Their mean age was 14.5 years. The mean treatment length was 2.4 years. The mean retention phase was 3.3 years. The mean pre- and posttreatment PAR scores were 29.8 (T1) and 6.3 (T2). The mean T1–T2 difference was 23.6. The mean T2–T3 difference was −0.39.Conclusions:Within the study, 7.1% presented absolute stability and 68.6% presented relative stability. Lower anterior segment alignment and overbite were the most unstable occlusal features and tended to worsen. Fixed retainer (odds ratio [OR] 0.31; 95% confidence interval [CI] 0.10–0.98) as a protective factor and years without retention (OR 1.32; 95% CI 1.03–1.68) as a risk factor are predictor variables of instability in the case of lower anterior segment alignment. The PAR value at the end of treatment (OR 1.29; 95% CI 1.08–1.54) and extractions (OR 4.76; 95% CI 1.05–21.6) before treatment are predictors for midline instability.