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Introduction: Proximal enamel thickness (PET) at the mesial and distal contact areas of the complete permanent dentition has not been previously reported. Anatomic investigation of PET is essential for interproximal reduction treatment. Our objectives were to measure the PETs of the complete maxillary and mandibular dentitions at the contact areas, to compare the PETs of adjacent teeth, and to evaluate the vertical position of each contact area., Methods: We evaluated 720 extracted teeth; of these, 109 intact teeth were selected. The mesial and distal contact areas were demarcated, and each tooth was embedded in transparent epoxy resin. Blocks were prepared so that the 2 demarcated contact areas were exposed, and 6 measurements were taken and statistically analyzed., Results: Both jaws showed the same PET pattern characterized by 5 features: PET increased progressively from incisor (0.63 mm) to first molar (1.48 mm). Per tooth, mesial and distal PET did not differ. Total maxillary (26.86 mm) and mandibular (24.52 mm) PETs were similar. Paired PETs at the interproximal interface were similar, with the exception of the lateral incisor-canine interfaces. From incisor to first molar, the contact area becomes located farther gingivally., Conclusions: The existing guideline of maximal 0.5-mm interproximal reduction per 2 adjacent teeth should be kept in the anterior region and could be increased to 1 mm in the posterior region, when an equal amount is removed., (Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Objective: Labial cervical vertical groove (LCVG), a dental anomaly found at the cervical region of upper permanent incisors, can be of esthetic, periodontal and prosthetic concern. The aim of this study was to define the prevalence and characteristics of LCVG., Design: Of the 1250 examined subjects, 66 exhibited an LCVG. This group (age 19.7+/-11.4 years) was then compared with a matched No-LCVG (control) group of 49 subjects (age 17.9+/-5.7 years). Six LCVG characteristics were examined: distribution, severity and location of LCVG in central (I(1)) and lateral (I(2)) permanent maxillary incisors, Angle's classification, gender and presence of LCVG in siblings., Results: Total LCVG prevalence was 5.3% (single 3.76%; multiple 1.53%), found predominantly in I(1) (93.9%) compared with I(2) (p=0.001). The anomaly presented mostly as a single configuration (71.21%); double configuration was predominantly homological bilateral, i.e., I(1)+I(1), or I(2)+I(2) (88%). LCVG in I(2) was mainly associated with multi-configuration (75%). The severe form occurred only in I(1). A mid-crown LCVG allocation was distinctive in I(1) (62.2%, p=0.001) and mesial-crown in I(2) (66.7%, p=0.038). LCVG was found mostly in males (p=0.045). In the LCVG group 16.7% were siblings., Conclusions: LCVG primarily involved I(1) in single configuration as the target assaulted tooth and secondarily I(2) mostly as a multi-configuration. The genetic impact on LCVG formation was primarily supported by the high prevalence in siblings and secondarily by the favourable occurrence in males, exclusive pattern of allocation within the crown and high occurrence of bilateral double-configuration LCVG.

Open bite (OB) is a generalized term, which could incorporate subgroups that react differently to vertical correction. The objectives of the present study were to detect vertical treatment changes in incomplete bite (IB: inter-incisor overlap with no lower incisor contact with teeth or palate) and OB (no inter-incisor overlap) groups compared with a complete bite (CB: inter-incisor overlap with full lower incisor contact with teeth or palate) control group, to evaluate treatment response of the central and lateral incisors, and to study the vertico-sagittal interaction. Dental casts were taken at three time points, pre-treatment, post-treatment, and after one year of retention, from 54 Class II patients (22 males and 32 females with a mean age of 11 years 6 months) divided into three groups: CB (n = 21), IB (n = 18) and OB (n = 15). Measurements included incisor overlap (mm) and optical density (OD/mm2) of occlusal bite registration made of polyvinl siloxane. Both CB and IB groups demonstrated post-retention bite opening. However, bite opening in the CB group was three times greater than that in the IB group (e.g. lower lateral = -1.42 mm, 118 OD/mm2 versus -0.40 mm, 107 OD/mm2). Conversely, the OB group showed a significant (P < 0.001) bite closure (e.g. lower lateral = 1.30 mm, -377 OD/mm2). Overjet changes affected OD measurements, causing diversity in OD and millimetric measurements of the lateral incisors in the IB group. In conclusion, the OB group demonstrated a significant stable vertical correction; a post-treatment non-contact inter-incisor relationship was determined by a vertico-sagittal relapse; and full compensation of an IB was not possible.

Objectives: To investigate the prevalence and severity of a labial-cervical-vertical groove (LCVG) in maxillary permanent incisors and its effect on the associated gingival tissue., Methods: A total of 600 adolescents (293 boys and 307 girls, mean age 13.6+/-1.99 years) were randomly selected and examined for the presence of LCVG. The deformity was classified as mild, moderate, or severe according to predetermined criteria. Gingival coverage at the groove site was defined as normal, partial, and irregular., Results: LCVG was found in 27 adolescents (4.5%). It was unilateral in 24 (89%) and bilateral in 3 (11%). The ratio of central to lateral incisors was 29:1. No sexual dimorphism or side prevalence were found. Mild LCVG was found in 22 incisors, moderate LCVG in 7 incisors, and severe LCVG in one incisor. Moderate LCVG was 5 to 6 times more susceptible to partial or irregular coverage of the gingival margin than mild LCVG. The gingival sulcus in teeth with LCVG demonstrated a significant (P = .001) increase in depth compared to non-LCVG teeth (1.55+/-0.90 mm vs 1.18+/-0.75 mm)., Conclusions: An LCVG is a deformity confined predominantly to a single permanent maxillary central incisor. Its prevalence is not connected with gender. Most LCVGs are mild and often difficult to detect. However, the greater the severity, the more gingival irregularity is associated. This and the increase in sulcus depth in LCVG incisors are adverse predispositions for periodontal sequelae, calling for cautious oral hygiene maintenance.

Root resorption after rapid palatal expansion (RPE) treatment was found in anchored teeth but has not been studied on non-anchored incisors. This study evaluated root resorption, root tipping, and root proximity of maxillary incisors after RPE treatment. Fourteen cats were divided into treated (n = 10) and untreated (n = 4) groups. The RPE treatment consisted of active, retention, and relapse phases, lasting 25, 60 and 60 d, respectively. Standardized occlusal radiographs were taken to measure tipping and root proximity before and after each treatment phase. Maxillary incisors were analysed histologically by fluorescent microscopy for root resorption. Data was analysed statistically with anova with repeated measures, t-test and Pearson's coefficient of correlation. Root resorption was confined to the first incisors and was 750-fold greater in the treated vs. the control group. Root tipping and root proximity were significantly greater (2.5- and 17-fold, respectively) in the first than in the second maxillary incisor and highly correlated with root resorption (r = -0.927 and 0.723, respectively). This suggests a cause (tipping and root proximity) and effect (root resorption) relationship. Data suggest that first maxillary incisor susceptibility to root resorption during RPE is associated with severe tipping and root proximity.