Reconsidering the role of nasolabial angle in premolar extraction decision-making: A case-series study.

OBJECTIVES: To evaluate the impact of changes in upper incisor inclination and position on the alteration of the nasolabial angle (NLA) in a series of cases involving the extraction of four first premolars. MATERIALS AND METHODS: The study included 41 patients who underwent orthodontic treatment with premolar extractions. The patients were divided into two groups based on their pretreatment NLA values: Group 1 (NLA ≤ 100°) and Group 2 (NLA > 100°). Measurements of NLA, U1.NA and U1-NA were obtained before and after treatment and U1-Ls pretreatment measure was registered. Statistical analyses were performed to compare the differences in NLA, U1.NA and U1-NA between the two groups and to evaluate the influence of these variables added to U1-Ls (T1) on NLA changes. RESULTS: The results showed that Group 1 exhibited significant changes in NLA, while Group 2 did not. However, both groups showed significant changes in U1.NA and U1-NA. In Group 1, 80% of the individuals presented an increase in NLA and 20% no changes. In Group 2, 10% presented a decrease, 57% no changes and 33% an increase in NLA values. Multiple linear regression analysis indicated that the group factor had a statistically significant influence on NLA variation. Additionally, in Group 2, a negative correlation was observed between changes in U1.NA and NLA. CONCLUSIONS: The findings suggest that individuals with higher pretreatment NLA values tend to maintain their NLA values even after the correction of upper incisor inclination.

Prosthetic replacement vs space closure for maxillary lateral incisor agenesis: A systematic review.

INTRODUCTION: Defining the best treatment for maxillary lateral incisor agenesis is a challenge. Our aim in this study was to determine, with the evidence available in the literature, the best treatment for maxillary lateral incisor agenesis in the permanent dentition, evaluating the esthetic, occlusal (functional), and periodontal results between prosthetic replacement and orthodontic space closure. METHODS: Electronic databases (CENTRAL, PubMed, Web of Science, Scopus, and LILACS) were searched in September 2014 and updated in January 2015, with no restriction on language or initial date. A manual search of the reference lists of the potential studies was performed. Risk of bias was assessed by the Newcastle Ottawa Scale. RESULTS: The search identified 2174 articles, of which 1196 were excluded because they were duplicates. Titles and abstracts of 978 articles were accessed, and 957 were excluded. In total, 21 articles were read in full, and 9 case-control studies were included after applying the inclusion and exclusion criteria. Data were extracted from the articles selected, and a table was compiled for comparison and analysis of the results. There were no randomization and blinding, and the risk of bias evaluation found gaps in compatibility and outcome domains in almost all selected studies. CONCLUSIONS: Tooth-supported dental prostheses of maxillary lateral incisor agenesis had worse scores in the periodontal indexes than did orthodontic space closure. Space closure is evaluated better esthetically than prosthetic replacements, and the presence or absence of a Class I relationship of the canines showed no relationship with occlusal function or with signs and symptoms of temporomandibular disorders.

Effect of a metal primer on the adhesive interface between composite and lingual brackets.

AIM: To test the null hypothesis was that there is no difference in the shear strength of indirectly bonded lingual brackets with or without prior application of metal primer on their bases. MATERIALS AND METHODS: Forty recently extracted human premolars were obtained and randomly divided into two groups of 20 each: group I (control), phosphoric acid and indirect bonding with Maximum Cure (Reliance Orthodontic Products, Itasca, IL, USA); and group II, application of metal primer (Metal Primer, Reliance Orthodontic Products) on bracket base prior to conditioning and indirect bonding. All products were used according to the manufacturer's instructions. A universal testing machine was used to apply a shear force directly onto the enamel- bracket interface at a speed of 1.0 mm/min. RESULTS: Mean (SD) shear bond strength for group I was 12.87 (5.75) MPa and for the group II was 18.47 (8.48) MPa. The Student's t-test showed a significant difference (p = 0.0311) between the groups. The chi-square test for the adhesive remnant index (ARI) indicated that there was a significant difference (p = 0.2750). CONCLUSION: The application of metal primer increased the adhesion of lingual brackets, and may be a promising procedure for clinical orthodontics.