• Journal of Periodontal and Implant Science
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• 제51권3호
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• pp.163-178
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• 2021

Purpose: The aim of this study was to evaluate clinical factors affecting the longevity of fixed retainers and the influence of fixed retainers on periodontal health in periodontitis patients. Methods: In total, 52 patients with at least 2 years of follow-up after periodontal and orthodontic treatment were included in this study. After scaling and root planing, orthodontic treatment with fixed appliances or clear aligners was performed. Fixed retainers with twist-flex stainless steel wires were bonded to the palatal or lingual sides of anterior teeth. Changes in clinical parameters, including the plaque index, gingival index, calculus index (CI), probing pocket depth, and radiographic bone levels, were evaluated before bonding of fixed retainers and at a 12-month follow-up. Cumulative survival rates (CSRs) for retainer failure were evaluated according to sex, site, CI, stage of periodontitis, and the severity of the irregularity with the log-rank test and hazard ratios (HRs). Results: Twelve months after bonding of fixed retainers, improvements were observed in all clinical parameters except CI and radiographic bone gain. The overall CSR of the retainers with a CI <1 at the 12-month follow-up after bonding of fixed retainers was significantly higher than that of the retainers with a CI ≥1 at the 12-month follow-up (log-rank test; P<0.001). Patients with stage III (grade B or C) periodontitis had a higher multivariate HR for retainer failure (5.4; 95% confidence interval, 1.22-23.91; P=0.026) than patients with stage I (grade A or B) periodontitis. Conclusions: Although fixed retainers were bonded in periodontitis patients, periodontal health was well maintained if supportive periodontal treatment with repeated oral hygiene education was provided. Nonetheless, fixed retainer failure occurred more frequently in patients who had stage III (grade B or C) periodontitis or a CI ≥1 at 12-month follow-up after bonding of fixed retainers.

• 대한치과교정학회지
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• 제54권4호
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• pp.257-263
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• 2024

Objective: Lingual fixed retainers, made from 0.0175-inch 3-strand twisted stainless steel wire (TW) and 0.016 × 0.022-inch straight rectangular wire (RW), are generally used in clinical practice. This study aimed to calculate their accuracy by comparing the discrepancy between computer-aided customized retainers made from these two types of wires. Methods: Eleven orthodontic patients were selected, resulting in 22 maxillary and mandibular three-dimensional printing dental models. Two types of lingual fixed retainers were bonded from canine to canine. To determine the accuracy, five points were chosen for each model, resulting in 110 selected points. The absolute values of the distances on the x-, y-, and z-axes were measured to compare the accuracy of the two types of computer-aided retainers. Results: The accuracy of the two types of retainers did not differ significantly in the x- and z-axes, but only in the y-axis (P < 0.01), where RW-fixed retainers exhibited a slightly but significantly increased distance compared to the TW. Conclusions: Both types of retainers showed high accuracy; however, RW had a slight but statistically significant difference along the y-axis compared with TW. This type of computer-aided design/computer-aided manufacturing bending machine is limited to two dimensions, and the dental arch is curved. Therefore, RW may require slight manual adjustment by the practitioner after manufacturing.

• 대한치과교정학회지
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• 제47권3호
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• pp.207-212
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• 2017

The popularity of clear overlay retainers (CORs) has increased recently because of their advantages such as better esthetics, cost effectiveness, easy fabrication, and good compliance. However, a deficiency in posterior occlusal settling is a reported limitation of CORs. The aim of this study was to evaluate the posterior occlusal contact changes in a new type of clear orthodontic retainer called Oral-treaper (OTP), which consists of three layers and has stronger mechanical characteristics than do conventional retainers. Three patients who completed fixed orthodontic treatment received OTP as a removable retainer. Cast models were fabricated after the removal of fixed appliances (T1) and after 4 to 11 months of using the retainers (T2). We evaluated all the cast models to compare the post-orthodontic settling pattern during the use of the OTPs. The depth of occlusal contacts was evaluated using color maps. The OTP did not prevent vertical settling in all patients but resulted in an improvement in posterior occlusal contact points.

• 대한치과교정학회지
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• 제46권1호
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• pp.36-41
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• 2016

Objective: The aim of this study was to evaluate retention practices commonly employed by orthodontists. The objectives were to identify the types of retainer frequently used and to investigate the variations in retention practice. Methods: A total of 97 orthodontists were randomly selected, and a questionnaire consisting of 25 multiple-choice questions sent to them by mail. Upon receiving of the completed questionnaires, the data were statistically analyzed. Results: A total of 32 responses were received; among these, 59.4% of orthodontists' practiced is in a government setting and 40.6% were in private practice. A vacuum-formed retainer was the most commonly used removable retainer for both maxillary (46.9%) and mandibular (46.9%) arches, followed by a Hawley retainer (maxilla, 43.8%; mandible, 37.5%), and a fixed retainer (maxilla, 3.1%; mandible, 9.4%). Of the responding orthodontists, 78.1% prescribed full-time wear (more than 20 h per day) for a duration of 3-9 months for a maxillary arch, compared to 71.9% for the mandibular arch. Only 18.8% of the orthodontists prescribed part-time wear of the retainer for the maxillary arch, compared to 21.9% for the mandibular arch. The majority of orthodontists did not instruct their patients to stop wearing removable retainers (71.9%) or fixed retainers (66.8%) at any specific time and they preferred their patients to continue wearing retainers. Conclusions: Vacuum-formed retainers are the most commonly used retainers among orthodontists. The majority of orthodontists prescribed full-time wear for more than 20 h per day with a duration of 3-9 months and preferred indefinite use of the retainer.

• 대한치과교정학회지
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• 제42권5호
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• pp.255-262
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• 2012

Objective: We aimed to compare the retention characteristics of Essix and Hawley retainers. Methods: Adolescents undergoing fixed appliance treatment at 2 centers were recruited for this study. Twenty-two patients (16 women and 6 men) wore Essix retainers (Essix group) while 20 (14 women and 6 men) wore Hawley retainers (Hawley group). The mean retention time was 1 year, and the mean follow-up recall time for both groups was 2 years. Two qualified dental examiners evaluated the blind patient data. Maxillary and mandibular dental casts and lateral cephalograms were analyzed at 4 stages: pretreatment (T1), post-treatment (T2), post-retention (T3), and follow-up (T4). Results: The results revealed that Essix appliances were more efficient in retaining the anterior teeth in the mandible during a 1-year retention period. The irregularity index increased in both arches in both groups after a 2-year post-retention period. The mandibular arch lengths increased during treatment and tended to return to their original value after retention in both groups; however, these changes were statistically significant only in the Hawley group. Cephalometric variables did not show any significant differences. Conclusions: The retention characteristics of both Essix and Hawley retainers are similar.

• 대한치과교정학회지
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• 제46권2호
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• pp.104-110
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• 2016

Objective: Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. Methods: In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (${\alpha}=0.05$). Results: In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Conclusions: Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.

• 대한치과교정학회지
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• 제53권6호
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• pp.365-373
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• 2023

Objective: To investigate the potential correlation between fixed orthodontic retention failure and several patient- and treatment-related factors. Methods: Patients finishing treatment with fixed appliances between 2016 and 2017 were retrospectively included in this study. Those not showing fixed retention failure were considered as control group. Patients with fixed retention failure were considered as the experimental group. Additionally, patients with failure of fixed retainers in the period of June 2019 to March 2021 were prospectively identified and included in the experimental group. The location of the first retention failure, sex, pretreatment dental occlusion, facial characteristics, posttreatment dental occlusion, treatment approach and presence of oral habits were compared between groups before and after treatment separately by using a Fisher exact test and a Mann-Whitney U test. Results: 206 patients with fixed retention failure were included, 169 in the mandibular and 74 in the maxillary jaws. Significant correlations were observed between retention failure in the mandibular jaws and mandibular arch length discrepancy (P = 0.010), post-treatment growth pattern (P = 0.041), nail biting (P < 0.001) and abnormal tongue function (P = 0.002). Retention failure in the maxillary jaws was more frequent in patients with IPR in the mandibular jaws (P = 0.005) and abnormal tongue function (P = 0.021). Conclusions: This study suggests a correlation between fixed retention failure and parafunctional habits, such as nail biting and abnormal tongue function. Prospective studies with larger study populations could further confirm these results.

• 대한치과교정학회지
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• 제40권5호
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• pp.325-333
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• 2010

발음장애, 구토감 및 착용 불편감과 같은 보정장치에 대해 환자가 느끼는 불편감을 평가해보기 위해 고정식 교정장치로 교정치료를 받고 교정장치가 제거된 66명(남자 23명, 여자 43명; 평균연령 $23.42{\pm}10.19$)의 교정환자를 대상으로 무작위로 두 군으로 배정한 후 고정식 교정장치를 제거한 다음 날 CWR 장착군에게는 구개를 완전히 덮는 구개 완전 피개형 보정장치인 conventional wraparound retainer (CWR)를 장착시키고 CCR 장착군에게는 구개를 말 발굽 모양으로 부분 피개하는 보정장치인 circumferential comfortable retainer (CCR)를 4주 동안 장착시킨 후 발음장애, 구토감 및 착용 불편감의 정도에 대해 100-mm visual analog scale (VAS)로 표시할 수 있도록 제작된 설문지를 통해 얻은 점수에 대해 통계적으로 비교 분석하였다. 연구결과 발음장애와 착용 불편감의 비교에서 CCR 장착군이 CWR 장착군에 비해 통계적으로 유의하게 낮았다 ($p$ < 0.05). 구토감의 비교에서는 CCR 장착군이 CWR 장착군에 비해 낮은 점수를 보였지만 통계적으로는 유의한 차이를 보이지 않았다 ($p$ = 0.146). 이상의 연구 결과로 circumferential comfortable retainer (CCR)는 발음장애를 감소시키고, 착용 불편감을 완화시킴으로써 환자의 협조도를 증진시켜줄 수 있는바 고정식 교정장치를 이용한 교정치료 후 치료결과 유지에 도움이 될 수 있음을 시사하였다.

• 대한치과보철학회지
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• 제43권6호
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• pp.707-716
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• 2005

Statement of problem. Collarless metal ceramic fixed partial dentures(FPDs) had an esthetic problem such as opaque reflection in cervical region. To overcome this, modified coping which removed its facial cervical metal could be used. The marginal quality could be worsen according to the amount of its facial metal reduction. Purpose. The purpose of this study was to evaluate marginal fits of collarless metal ceramic FPDs with retainers of modified copings. Material and method. Dentoform maxillary left central incisor and right lateral incisor were prepared for 3-unit collarless metal ceramic FPD and fixed in yellow stone. This model was duplicated to PBT resin dies via CAD/CAM and injection molding. Four different facial margin design groups were investigated. Group A was a coping with a thin facial metal collar, group B was a collarless coping with its facial metal to the shoulder, group C was a collarless coping with its facial metal 1 mm short of the shoulder, and group D was a collarless coping with its facial metal 2 mm short of the shoulder. Seven collarless metal ceramic FPDs per group were fabricated. They were cemented to PBT resin dies with resin cement. After removal of pontics, each retainers were separated and observed under Accura 2000 optical microscope. Then, retainers were embeded in orthodontic resin and cross sectioned faciopalatally. Internal marginal fits of midfacial porcelain margins were observed under FE-SEM. Result and conclusion. Within the limitations of this in vitro study. The following conclusions were drawn. 1. Mean marginal gaps of collarless FPDs were in the $50-60{\mu}m$ range. 2. In midfacial margin, marginal discrepancies were greater in group A than in the experimental groups(p<0.05). 3. In midpalatal margin, marginal gaps were greater in group C and D than in group A and B(p<0.05). 4. Marginal fits of porcelain margins were better than those of metal margins in collarless metal ceramic FPDs. 5. In both teeth, internal marginal gaps of group C and D were greater than those of group A and B(p<0.05).

• 대한치과의사협회지
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• 제45권12호통권463호
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• pp.753-760
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• 2007

노화가 진행되고 있는 중, 장년층의 교정치료시에 통상적인 교정치료의 방법과 함께 다음과 같은 사항을 고려하여야 한다. 1. 치주질환 존재시 교정치료전 치주치료를 선행하여야 한다. 2. 발치 치료가 필요할 경우 치주 상태 및 치아 상태를 고려하여 발치할 치아를 선정하여야 한다. 3. 기존 보철물 존재시 보철물의 상태, 고정원으로 사용여부, 크기 조절 필요 여부, 환자의 경제적 상황 등을 고려햐여 처치한다. 4. 치료 종료 후 가철식 유지장치보다는 고정식 보정장치를 이용하여 치아의 유지력을 보강하는 것이 권장된다.