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OBJECTIVES: This study quantified the long-term occlusal wear in the natural posterior teeth and the associations per tooth type within the dentition. METHODS: The sample included 70 orthodontically treated subjects (52 females and 18 males; median age, 14.3 years), followed for a 12.7-year period. They were consecutively selected with no tooth wear-related criteria. Post-treatment (T1) and follow-up dental casts (T2) were scanned and superimposed through three-dimensional methods. Occlusal wear volume of posterior teeth and tooth wear patterns were investigated through non-parametric statistics and analysis of covariance. RESULTS: There were no significant differences between contralateral teeth. The average occlusal wear per posterior tooth was 2.3 mm3, with 65.2% of teeth showing values greater than 1 mm3. Males, mandibular teeth, and first molars exhibited slightly greater wear levels than females (median, 2.57 and 2.21 mm3, respectively; p = 0.005), maxillary teeth, and first or second premolars, respectively. In all first premolars and in the mandibular second premolars, the buccal cusps were primarily affected with no other distinct patterns. There were weak to moderate correlations between tooth types, apart from certain strong correlations detected in males. CONCLUSIONS: Posterior tooth wear was highly prevalent after a 13-year period starting at the onset of permanent dentition. The detected patterns are in accordance with the concept of canine guidance occlusion that is transforming into group synergy through function. CLINICAL RELEVANCE: The widespread tooth wear occurrence and the high intra- and inter-individual variability underline the need for individual patient monitoring to identify high-risk patients at early stages.
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Atrición Dental , Desgaste de los Dientes , Masculino , Femenino , Humanos , Adolescente , Dentición Permanente , Diente Molar , Diente PremolarRESUMEN
In modern humans, tooth wear can easily be observed as a loss of tooth substance, but its precise measurement is problematic. The aim of this longitudinal cohort study was to determine the precise amount of occlusal tooth wear in the anterior permanent dentition from adolescence to adulthood. Corresponding tooth crowns from serial 3D digital dental models of 72 individuals were best fit-approximated by applying novel, highly accurate 3D superimposition methods. The superimposed crowns were simultaneously sliced on intact structures, and the differences in the volumes of the subsequent occlusal parts were calculated. Over a thirteen-year period, there was an average loss of anterior occlusal surfaces of 1.58 mm3 per tooth. Tooth surface loss in at least one tooth was higher than 1 mm3 in 93.1% of the human subjects. Tooth wear severity differed by sex and tooth type, with males showing higher values versus females and upper canines versus other anterior teeth. The study revealed the endemic occurrence of occlusal anterior tooth wear, highlighting the need for monitoring of the condition in the population to identify high-risk patients and enable timely interventions. The novel methods applied here on 3D digital models are recommended for this.
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PURPOSE: This retrospective cohort study investigated the long-term effectiveness of one type of maxillary and 2 types of mandibular fixed lingual retainers. MATERIALS AND METHODS: Eighty orthodontic patients in retention for 10-15 years were included. Irregularity index, intercanine width, overjet (OJ) and overbite (OB) were measured on plaster models at 3 occasions: (T1) pre-treatment, (T2) post-treatment and (T3) 10-15 years post-treatment. Analyses assessed the effect of the retainer type and time on mandibular irregularity, intercanine width and retainer failure. RESULTS: In the mandible, the irregularity index increased (0.43 mm) between T2 and T3 for the 0.027" ß-titanium (TMA) retainers bonded to canines only while it was stable (-0.02 mm) for the 0.016" x 0.022" braided stainless steel retainers (SS6) bonded to all six anterior teeth. The intercanine width was relatively stable in both groups during the entire observation period. In the maxilla, the irregularity index was stable between T2 and T3 (+0.07 mm). The intercanine width increased (+2.02 mm) during treatment T1-T2 and was stable (-0.02 mm) in the retention phase T2 to T3. CONCLUSIONS: In the mandible, SS6 retainers were slightly more effective in maintaining alignment compared to the TMA retainers. In the maxilla, the SS4 retainers without canine extensions were effective in maintaining alignment. All retainers were effective in maintaining the intercanine width.
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Maloclusión Clase II de Angle , Maxilar , Humanos , Mandíbula , Retenedores Ortodóncicos , Estudios RetrospectivosRESUMEN
BACKGROUND: The long-term evidence regarding failures of fixed retainers is limited and the aim of this cohort study was to assess the long-term risk of failure of one type of maxillary and two types of mandibular fixed lingual retainers. TRIAL DESIGN: Retrospective cohort study. METHODS: Eighty-eight patients in retention 10-15 years after orthodontic treatment were included. The type of failure; number of failures per tooth, per patient, and retainer; and adverse effects were assessed by (1) a questionnaire, (2) clinical examination, and (3) screening patients' clinical charts. Descriptive statistics were calculated and a Cox regression was used to assess possible predictors for mandibular retainer survival. RESULTS AND CONCLUSIONS: In the mandible, 47 (53.4%) .016â³ × .022â³ braided stainless steel retainers (SS) were bonded to all six anterior teeth, and 41 (46.6%) .027â³ ß-titanium (TMA) retainers were bonded to the canines only. From the SS retainers 40.4% and of the TMA retainers 61% had no failures during the whole observation period. SS failures per retainer were 2.17 (3.15) vs. 0.66 (1.03) for TMA. The type of retainer was the only significant predictor for failure. In the maxilla, 82 (93.2%) .016â³ × .022â³ braided SS retainers were bonded to all four incisors and six retainers (6.8%) to all six anterior teeth. The latter group was not further analyzed due to the small sample size. From the retainers bonded to all four incisors, 74.4% had no failure during the whole observation period. SS average number of failures per retainer bonded to the four incisors was 1.14 (SD 2.93). Overall, detachments were the most frequent type of first failure followed by composite damage. From the original mandibular retainers 98.9% and of the original maxillary retainers 97.6% were still in situ 10-15 years after debonding. No adverse torque changes were observed. LIMITATIONS: Potential effects of selection bias, information bias, and attrition bias as well as possible confounding factors cannot be fully excluded in this study.
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Recubrimiento Dental Adhesivo , Maxilar , Estudios de Cohortes , Humanos , Mandíbula , Diseño de Aparato Ortodóncico , Aparatos Ortodóncicos Fijos , Retenedores Ortodóncicos , Estudios RetrospectivosRESUMEN
INTRODUCTION: The aims of this study were to retrospectively investigate the long-term development of gingival recession in a cohort of orthodontic patients and to compare the prevalence of gingival recession in orthodontically treated patients 10 to 15 years posttreatment to that of untreated subjects with malocclusion. METHODS: The sample included 88 patients with mean ages of 12.1 years (SD, 2.4 years) at pretreatment, 15.1 years (SD, 2.4 years) at posttreatment, and 27.9 years (SD, 2.5 years) 10 to 15 years posttreatment. The control group comprised 102 untreated patients seeking orthodontic treatment with a mean age of 28.7 years (SD, 3.1 years). Gingival recession was evaluated on study models. RESULTS: The prevalence of both labial/buccal and lingual/palatal gingival recession increased during orthodontic treatment with further increases during the long-term posttreatment period; 98.9% of the orthodontically treated participants had at least 1 labial/buccal recession, and 85.2% of the patients had at least 1 lingual/palatal recession 10 to 15 years posttreatment. In addition, the proportion of patients with multiple labial/buccal or lingual/palatal recession sites increased considerably in the same time period. The prevalences of labial/buccal gingival recession were similar in the orthodontically treated patients 10 to 15 years posttreatment and the untreated controls. Study group patients with a crossbite before treatment showed 2.73 more recessions (95% CI, 0.28-5.17; P = 0.029) than did those without a transverse discrepancy. Untreated subjects with crowding greater than 3 mm per arch had 3.29 more recessions (95% CI, 0.73-5.68; P = 0.012) to 4.92 more recession sites (95% CI, 1.70-8.15; P = 0.003) than did those with mild or no crowding. CONCLUSIONS: Within the limitations of this study, it seems that, in regard to the prevalence of gingival recession, orthodontically treated patients are not compromised in the long term compared with those with malocclusion that was untreated for many years.
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Recesión Gingival/etiología , Ortodoncia Correctiva/efectos adversos , Adolescente , Adulto , Niño , Estudios de Cohortes , Femenino , Humanos , Masculino , Estudios Retrospectivos , Factores de Tiempo , Adulto JovenRESUMEN
Aim: To assess the association between tooth wear (TW) and gingival recession (GR). Materials and Methods: Two hundred and ten orthodontically treated participants (100 males) were evaluated. GR and TW were rated independently by four raters on plaster models at four time points: before treatment (T1), mean age 13.8 years (SD = 3.7); after treatment (T2), mean age 16.7 years (SD = 3.9); 3 years after treatment (T3), mean age 19.7 years (SD = 4.2); and 7 years after treatment (T4), mean age 23.9 years (SD = 4.8). Univariable and mulitvariable random effects logistic regression analyses were performed with scores for GR as dependent variables and with TW, age, gender, dental segments (maxillary and mandibular anterior and posterior segments), time points, and Angle classification as independent variables. Method reliability was assessed with kappa statistics. Results: Mandibular incisors, mandibular and maxillary first premolars and maxillary first molars were most vulnerable to GR. The prevalence of GR increased during the observation period. At T1 20.5% participants had one or more recession sites, at T4 85.7 % of the participants had at least one GR. There was evidence of association between moderate/severe TW and GR-for a tooth with moderate/severe wear, the odds of recession were 23% higher compared to a tooth with no/mild wear (odds ratio 1.23; 95% CI: 1.08-1.40; P = 0.002). Age, dental segment, and time were also significant recession predictors, whereas gender was not. Conclusions: There is evidence that moderate/severe TW is associated with the presence of gingival recession. Clinical significance of this can be limited.