RESUMO
BACKGROUND: New technologies have paved the way for newer fabrication techniques, such as rapid prototyping, which has gained popularity in the fabrication of several orthodontic appliances including retainers. AIM: To evaluate the stability, survival time and periodontal health associated with vacuum-formed retainers (VFRs), bonded retainers (BRs) and rapid prototype retainers (RPRs) over a period of 12 months in retention. STUDY DESIGN: Prospective clinical study. METHODS: A total of 72 participants completing fixed orthodontic treatment were allocated to the following three groups by the investigators based upon their initial malocclusion, compliant and preferences: VFR; BR; and RPR. The primary outcome was Little's Irregularity Index (LII). Other stability parameters, including arch length (AL), inter-canine width (ICW) and inter-molar width (IMW), were also assessed immediately after debonding (T0) and 12 months (T2) after debonding. In addition, survival time, and calculus index and gingival index (GI) were assessed. RESULTS: LII showed a significant difference (P = 0.00) between the groups and was increased in the VFR group (0.18 ± 0.22 mm) compared to the BR (0.03 ± 0.05 mm) and RPR (0.01 ± 0.03 mm) groups but was not clinically significant. The mean survival time of maxillary retainers was longest for the RPR group (220.63 days; 95% confidence interval [CI] = 194.1-247.16) but there was no significant difference between the three groups (P = 0.43). The mean survival time of mandibular retainers was higher and the same for the VFR and RPR groups (240 days; 95% CI = 240-240) and there was no significant difference between the three groups (P = 0.38). The calculus index score (P = 0.00) was statistically significant between the groups, with an increased score for the BR group (0.33 ± 0.27) compared to the VFR (0.07 ± 0.16) and RPR (0.13 ± 0.22) groups. Similarly, the GI score (P = 0.02) was statistically significant between the groups and was increased in the BR group (0.01 ± 0.19) compared to the VFR (-0.15 ± 0.18) and RPR (-0.06 ± 0.15) groups. The increase in calculus index and GI scores for the BR group were not clinically significant. CONCLUSION: There were no clinically significant differences between the three retainer groups in terms of stability, periodontal health and time to failure.
RESUMO
OBJECTIVES: To assess and evaluate the collum angle (CA) of the anterior teeth of the permanent dentition. METHODS: A search in seven databases for articles that had measured the CA in sagittal malocclusions was conducted until November 30, 2021. The risk of bias was assessed using the Modified Newcastle Ottawa scale. CA measurements using Cone Beam Computed Tomography or lateral cephalograms were included. The CA data were summarized by random-effects inverse generic meta-analyses. RESULTS: Qualitative analysis of the 17 selected articles revealed that four were rated as "very good," 12 as "good" and 1 as "satisfactory." CA was 4.7° (95% CI of 3.1 to 6.4) and 2.0° (95% CI of 0.1 to 3.9) greater in Class II division 2 and Class III malocclusions respectively, than in Class I malocclusion cases. CONCLUSION: Majority of the studies were rated as good or very good. Most studies evaluated the CA of the maxillary central incisors in Class II division 2 malocclusion. Studies assessing other maxillary anterior and mandibular anterior teeth are required. CLINICAL SIGNIFICANCE: Practice of esthetic dentistry for teeth with increased CA is of clinical importance since the angle would determine the longevity and esthetic/cosmetic success of the rehabilitation. Placement of dental implants in areas of missing teeth with increased collum angle leads to excessive stress between the fixture and abutment leading to gingival recession. Thus, knowledge about the collum angle of anterior teeth and its variations in sagittal malocclusions would enable precise treatment planning in the field of esthetic dentistry.
