Evaluation of posttreatment stability after orthodontic treatment in the mixed and permanent dentitions

Objective:To investigate posttreatment changes in the maxillary and mandibular arches in patients who underwent orthodontic treatment during the mixed and permanent dentitions.Materials and Methods:The sample was collected retrospectively from three private practices and consisted of 42 patients who were at least 10 years out of orthodontic treatment. The longitudinal records of study casts and cephalometric radiographs were analyzed to quantify posttreatment changes.Results:Minimal changes in maxillary and mandibular irregularity occurred after an average of 16.98 years from completion of treatment. More than 10 years posttreatment, approximately 81% of the maxillary anterior teeth and 88% of the mandibular anterior teeth showed clinically acceptable incisor alignment (<3.5 mm). Mandibular fixed retainers greatly aided in maintaining the stability of the mandibular incisor alignment. However, posttreatment changes in maxillary incisor irregularity did not appear to be influenced by the presence of a mandibular fixed retainer. When compared with longitudinal changes observed in untreated subjects, the increase in incisor irregularity resembled a pattern similar to the regression line of untreated subjects and seems to be entirely age related. Arch width and arch depth was consistently decreased after treatment, but the magnitude of change was minimal at about 1 mm. No associations were found between any of the cephalometric measurements and changes in incisor irregularities.Conclusions:Orthodontic treatment stability can be achieved and mandibular fixed retention appears to be a valuable contributor, especially in patients with further growth expected.     

Periodontal health of anterior teeth with two types of fixed retainers

Objective:To compare the periodontal health of maxillary and mandibular anterior teeth retained with two types of fixed retainers.Materials and Methods:A fixed straight retainer (SR) group had 39 subjects, and a fixed wave retainer (WR) group had 35 subjects. Subjects were between the ages of 13 and 22 years and had been in fixed retention for 2 to 4 years. Pocket probing depths, bleeding on probing, plaque index, calculus index, recession, and gingival crevicular fluid volume were compared between the two retainer groups. A four-question oral hygiene survey was given to each subject. The Mann-Whitney U-test and Fisher exact test was used to analyze the data.Results:There was no clinically significant difference between the retainer groups regarding plaque index, gingival crevicular fluid volume, calculus index, recession, bleeding on probing, and pocket probing depths. A statistically significant increase in the reported frequency of flossing (P  =  .006) and ease of flossing (P < .001) was associated with the WR group. There was no significant difference between the groups in reported frequency of brushing and comfort of the retainer.Conclusions:Under the conditions of this study, no clinical difference was found in the periodontal health of anterior teeth retained with a SR or WR for a period of 2 to 4 years. Subjects in the WR group reported an increase in frequency and ease of flossing.     

义齿磁性固位体中两种不锈钢的细胞毒性研究

目的 对将使用于义齿磁性固位体的两种特殊不锈钢（S1与S2）的生物安全性进行初步检测,评价其临床应用的生物相容性。方法 用纯钛及钴铬合金作比较,通过将材料浸提液与体外培养的L-929细胞接触培养,进行细胞的形态学观察及二甲基噻唑二苯基四唑嗅盐（MTT）比色,评价材料对细胞造成的毒性损害程度。结果 细胞的形态学观察显示,随着培养天数的增加,阳性对照组中的脱落细胞、死亡细胞逐渐增多。其余各组细胞大部分继续贴壁生长。细胞密度增加。MTT比色法结果显示,非磁性不锈钢（S1）和磁性不锈钢（S2）浸提液对细胞有轻微的毒性,细胞相对增殖率（RGR）降低3％,钴铬合金对细胞表现出1级细胞毒性,RGR降低11％,但4种金属材料组与阴性对照组的吸光度值之间的差异均无统计学意义（P>0.05）。结论 S1、S2两种不锈钢仅具有极微弱的细胞毒性,符合临床应用的要求。     

套筒冠固位加中空式赝复体修复老年人肿瘤术后单侧上颌骨缺损

目的:随访观察1-5年套筒冠固位加中空式赝复体修复老年人肿瘤术后的单侧上颌骨缺损的效果。方法:选择2005年1月至2010年1月门诊60岁以上老年人肿瘤术后的单侧上颌骨缺损伴牙槽骨缺失,口鼻相通伴发音差,健侧余留牙严重磨耗致咬合间隙小。采用套筒冠固位加中空式赝复体修复26例,随访观察1-5年复查修复体的密合性,美观与舒适,固位及稳定性,咬合关系和咀嚼功能,基牙牙周组织等。结果:随访观察1-5年套筒冠固位加中空式赝复体修复后效果:满意61.5%,基本满意34.6%,差3.8%,总满意率96.1%。结论:套筒冠固位加中空式赝复体修复老年人肿瘤术后的单侧上颌骨缺损效果较满意。     

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目的比较分析Hawley保持器和透明压膜保持器的正畸治疗保持效果。方法从2006年1月至2007年6月在湖北省襄阳市口腔医院正畸科采用直弓丝矫治器治疗矫治完成的各种错畸形病例中选择60例,按双盲法随机分成2组,30例应用Hawley保持器,30例应用透明压膜保持器进行保持,保持器均佩戴2年。在模型上测量保持前、后的PAR指数的7项指标(牙齿排列、覆盖、覆、中线、颊舌向关系、近远中关系、垂直向关系),评价复发情况。结果戴用保持器2年前后的指标变化均为透明压膜保持器组小于Hawley保持器组,但只有牙齿排列、覆、颊舌向关系方面差异有统计学意义,其余各项指标变化比较差异无统计学意义。结论在直丝弓矫治器治疗术后戴用保持器2年,透明压膜保持器与Hawley保持器相比在牙齿排列、覆、颊舌向关系方面有更加稳定的保持效果。     

热压膜透明联冠保持器的临床应用研究

目的：综合评价热压膜透明联冠保持器的临床应用特点及疗效.方法：将通过固定矫治技术完成矫治后的各类错（牙合）80例随机分为实验组、对照组,每组40例.实验组用热压膜透明联冠保持器,对照组用改良式Hawley＇s保持器,观察时间6个月.观察指标：①对保持器的主观认同感;②保持疗效;③因保持器本身问题的复诊率;④技工室、临床操作时间、操作工序比较.结果：①主观认同感方面无论是对美观、发音的影响,还是戴用舒适度、保持器固位情况、及取戴难易程度方面,二者均存在显著性差异;②临床、技工室制作所需时间,二者也存在显著性差异;③因保持器本身问题的复诊率及保持疗效方面,二者虽有差异,但差异无显著性.结论：热压膜透明联冠保持器较改良式Hawley＇s保持器无论在患者认同感,还是临床、技工室操作方面均表现出明显优越性,且保持疗效确切,适宜临床普及推广.     

A bonding technique for fixed maxillary retainers

Abstract

Maintaining incisor alignment is an important goal of orthodontic retention and can only be guaranteed by placement of an intact, passive and permanent fixed retainer. Here we describe a reliable technique for bonding maxillary retainers and demonstrate all the steps necessary for both technician and clinician. The importance of increasing the surface roughness of the wire and teeth to be bonded, maintaining passivity of the retainer, especially during bonding, the use of a stiff wire and correct placement of the retainer are all discussed. Examples of adverse tooth movement from retainers with twisted and multistrand wires are shown.     

3种常用正畸保持器的特点及临床应用

长期的稳定保持是正畸治疗的一个重要环节,但保持方法灵活多变,临床中应该根据错的类型适当选取保持方法。Hawley保持器、压膜式透明保持器、固定式舌侧保持器是临床中3种常用的保持器,本文将从保持效果、对牙周健康的影响、依从性以及舒适度4个方面进行综述,为临床合理选择保持器提供参考。     

A comparative evaluation of lingual retainer failure bonded with or without liquid resin: A randomized clinical study with 2-year follow-up

Objective:To prospectively evaluate and compare the effect of liquid resin on lingual retainer failure after a 2-year follow-up.Materials and Methods:Fifty-two patients (26 males, 26 females) with a mean age of 18.3 ± 1.3 years at follow-up, were randomized into two groups: the resin group and the nonresin group. The lingual retainers in the resin group were bonded to the enamel surfaces with two-step bonding resin, Optibond FL, and Tetric EvoFlow. The nonresin group followed the same procedure of bonding retainers but without applying the Optibond FL. Retainer failure, calculus accumulation, and discoloration of composite pads adjacent to the retainers during the 2-year observation period were registered, compared, and statistically analyzed with a Fisher''s exact test and chi-square test.Results:In the resin group, the incidence of retainer failure was 4% and occurred at the composite-wire interface; in the nonresin group, the incidence was 27% and occurred at the enamel-composite interface. The difference between the groups was statistically significant (P  =  .049). The incidences of calculus accumulation and discoloration adjacent to the composite pads were 27% and 69% (P  =  .003 and P < .001) higher in the nonresin group, respectively.Conclusion:Application of resin in bonding of lingual retainers appears to reduce the incidence of retainer failure as well as the incidence of calculus accumulation and discoloration adjacent to the composite pads.     

Long-term effects of different cleaning methods on copolyester retainer properties

Objective:To evaluate light transmittance, surface roughness, and flexural modulus of copolyester retainer material after long-term exposure to different cleaning methods.Materials and Methods:Standardized copolyester retainer specimens (ACE) were subjected to seven chemical cleaning solutions for 6 months: Invisalign cleaning crystals, Retainer Brite, Polident, Listerine mouthwash, 2.5% acetic acid, 0.6% NaClO, and 3% H₂O₂. Seventy specimens (n = 10 per method, 50.8 mm × 12.7 mm × 1.0 mm) were exposed to the different solutions twice a week for 2 minutes or according to manufacturer''s instructions and stored in artificial saliva at 37°C. Another group of specimens (n = 10) was brushed with a standardized toothbrushing machine for 2 minutes twice a week. At baseline and 6 months, light transmittance, surface roughness and flexural modulus of the specimens were quantified using spectrophotometry, profilometry, and three-point bend testing, respectively. Qualitative assessment was performed using scanning electron microscopy (SEM). Statistical analyses were accomplished at a significance level of .05.Results:The results indicated that light transmittance through the specimens decreased significantly from baseline for all cleaning methods at 6 months. Flexural modulus of the specimens decreased significantly for all cleaning methods except Invisalign crystals and Retainer Brite (P > .05). The Listerine group demonstrated the worst light transmittance change while H₂O₂ demonstrated the greatest change in flexural modulus of the specimens compared with other cleaning methods; however, no qualitative difference was observed using SEM analysis.Conclusions:The results suggest that different cleaning methods affect long-term physical properties of the ACE retainer material. At the present time, none of these cleaning methods is ideal for copolyester retainer material.