Luiz Gonzaga Gandini

Influence of maxillary incisor edge asymmetries on the perception of smile esthetics among orthodontists and laypersons

INTRODUCTION Our objective was to determine the perception of smile esthetics among orthodontists and laypeople with respect to asymmetries on the maxillary incisor edges in a frontal smile analysis. METHODS Two frontal close-up smile photos of 2 women, 1 white and 1 Afro-Brazilian, were selected for this study. Both smiles displayed healthy maxillary anterior dentitions. The images were digitally altered to create tooth wear on the maxillary left central and lateral incisors in 0.5-mm increments. The final images were randomly assembled into a photo album that was given to 120 judges, 60 orthodontists and 60 laypersons. Each rater was asked to evaluate the attractiveness of the images with visual analog scales. The data collected were statistically analyzed with 1-way analysis of variance with the Tukey post-hoc test and the unpaired Student t test. RESULTS The most attractive smiles in both types of smiles were those without asymmetries and the 0.5-mm wear in the lateral incisor. In general, tooth wear was considered unattractive by both groups of raters following a pattern: the more tooth wear, the more unattractive the smile; tooth wear in the central incisor was considered more unattractive than in the lateral incisor. For both group of raters, 0.5 mm of wear in the central incisor was considered unattractive, whereas the thresholds for lateral incisor discrepancies were 0.5 mm for orthodontists and 1.0 mm for laypersons. CONCLUSIONS The result of this study corroborates the clinical assumption that symmetry between the maxillary central incisors is a paramount goal for esthetic treatments.

Group A T-loop for differential moment mechanics : An implant study

INTRODUCTION When anchorage control is critical and compliance is less than ideal, efficient treatment depends on differential tooth movements. The purpose of this study was to evaluate the distal tipping of partially retracted canines and the mesial movement of the molars. METHODS Eleven patients had their maxillary and mandibular canines partially retracted with TMA (Ormco Corp, Orange, Calif) T-loop springs with 45 degrees gable bends distal to the loops preactivated for group A (maximum anchorage). Metallic bone markers served as references. The canines were retracted until enough space was available for alignment of the incisors without proclination. Oblique (45 degrees) radiographs were taken immediately before the initial activation and after partial retraction. The radiographs were scanned, superimposed on the bone markers, and measured digitally. RESULTS The mandibular canine crowns were retracted (4.1 +/-1.9 mm) and intruded (0.7 +/- 0.3 mm) by uncontrolled tipping. In contrast, the maxillary canine crowns were retracted (3.2 +/- 1.4 mm) by controlled tipping. The maxillary and mandibular molars crowns were protracted by similar amounts (1.0 +/- 0.6 and 1.2 +/-1.2 mm, respectively) by controlled tipping, without significant extrusion. The molars were protracted approximately 0.3 mm for every 1 mm of canine retraction. CONCLUSIONS The T-loop spring used in this investigation produced controlled tipping of the maxillary canines, but it did not produce controlled tipping of the mandibular canines or translation of the molar as expected.

Maxillary and mandibular width changes studied using metallic implants.

The purpose of this implant study was to evaluate the transverse stability of the basal maxillary and mandibular structures. The sample included 25 subjects between 12 and 18 years of age who were followed for approximately 2.6 years. Metallic implants were placed bilaterally into the maxillary and mandibular corpora before treatment. Once implant stability had been confirmed, treatment (4 first premolar extractions followed by fixed appliance therapy) was initiated. Changes in the transverse maxillary and mandibular implants were evaluated cephalometrically and two groups (GROW+ and GROW++; selection based on growth changes in facial height and mandibular length) were compared. The GROW++ group showed significant width increases of the posterior maxillary implants (P <.001) and the mandibular implants (P =.009); there was no significant change for the anterior maxillary implants. The GROW+ group showed no significant width changes between the maxillary and mandibular implants. We conclude that (1) there are significant width increases during late adolescence of the basal mandibular and maxillary skeletal structures and (2) the width changes are related with growth potential.

Accidental swallowing of orthodontic expansion appliance key

Ingestion of a foreign object, including a dental object, can lead to a trip to the emergency room. This article describes the accidental swallowing of a key that was used to activate a rapid maxillary expander. An orthodontic patient swallowed the key while trying to activate the appliance at home. The objects trajectory was followed on radiographs until it was eliminated. Possible clinical complications, legal implications of this situation, and practices for prevention are described.

Influence of the Vertical Position of Maxillary Central Incisors on the Perception of Smile Esthetics Among Orthodontists and Laypersons

OBJECTIVE The purpose of this study was to determine the perception of smile esthetics among orthodontists and laypeople with respect to different upper central incisor vertical positions in a frontal smile analysis. MATERIALS AND METHODS A frontal close-up smile photo of an adult Caucasian woman was selected. The patient had healthy upper anterior dentition and had no history of orthodontic treatment. Images were altered in order to create six different central incisor vertical positions in 0.5-mm increments. All images were assessed in three different views: full smile, gingival close-up excluding incisal edges, and incisal close-up excluding gingival margins. Images were randomly assembled in an album, which was given to 120 judges: 60 orthodontists and 60 laypersons. Each rater was asked to evaluate the attractiveness of the images using the visual analog scale. The data collected were then statistically analyzed. RESULTS The highest rated smiles showed two notable characteristics: the central-to-lateral incisal step was 1.5 mm; and the central incisor gingival margins matched the laterals, and both were 0.5 mm below the line of the canine gingival margins. The least attractive smile was the one with no step between the centrals and laterals, and with the central incisor gingival margins 1.0 mm above the canine gingival margins. CONCLUSION The results of this study indicate that slightly extruded upper central incisors are more esthetically preferred than intruded. CLINICAL SIGNIFICANCE The upper central incisors are the key determinant in evaluating smile esthetics, and thus, the assessment of their ideal vertical positioning is an aspect of paramount importance.

Changes over time in canine retraction: An implant study

INTRODUCTION The objective of this study was to analyze rates of canine movement over the first 2 months of continuous retraction, when rate changes are expected. METHODS Ten patients with bone markers placed in the maxilla and the mandible had their canines retracted over a 2-month period. Retraction was accomplished with beta-titanium alloy T-loop springs. Standardized 45 degrees oblique cephalograms where taken initially and every 28 days thereafter. The radiographs were scanned and digitized twice (the average was used for the analyses). The radiographs were superimposed by using the bone markers and oriented on the functional occlusal plane. Paired t tests were used to compare side and jaw effects. RESULTS There were no significant differences between sides. The maxillary cusp was retracted 3.2 mm, with less movement during the first (1.1 mm) than during the second 4 weeks (2.1 mm). The maxillary apices did not move horizontally. There were no significant vertical movements in the cusps and apices of the maxillary canines. The mandibular cusp was retracted 3.8 mm-1.1 mm during the first and 2.7 mm during the second 4 weeks. The mandibular apices were protracted 1.1 mm. The cusps and apices were intruded 0.6 and 0.7 mm, respectively. The only difference between jaws was the greater protraction of the mandibular apices during the second 4 weeks and in overall movement. CONCLUSIONS The rate of canine cusp retraction was greater during the second than the first 4 weeks. The mandibular canines were retracted by uncontrolled tipping whereas the maxillary canines were retracted by controlled tipping.

Photoelastic analysis of forces generated by T-loop springs made with stainless steel or titanium-molybdenum alloy

INTRODUCTION The purpose of this study was to use photoelastic analysis to compare the system of forces generated by retraction T-loop springs made with stainless steel and titanium-molybdenum alloy (TMA) (Ormco, Glendora, Calif) with photoelastic analysis. METHODS Three photoelastic models were used to evaluate retraction T-loop springs with the same preactivations in 2 groups. In group 1, the loop was constructed with a stainless steel wire, and 2 helicoids were incorporated on top of the T-loop; in group 2, it was made with TMA and no helicoids. RESULTS Upon using the qualitative analysis of the fringe order in the photoelastic model, it was observed that the magnitude of force generated by the springs in group 1 was significantly higher than that in group 2. However, both had symmetry for the active and reactive units related to the system of force. CONCLUSIONS Both springs had the same mechanical characteristics. TMA springs showed lower force levels.

Comparison surface characteristics and chemical composition of conventional metallic and nickel-free brackets.

This study aims at comparing conventional and nickel-free metal bracket surface characteristics with elemental composition by scanning electron microscopy (SEM), using energy dispersive spectroscopy (EDS). The sample consisted of 40 lower incisor brackets divided into four groups: ABZ = conventional brackets, Kirium Abzil 3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10); NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-free brackets, Roth Max Morelli® (n = 10). Qualitative evaluation of the bracket surface was performed using SEM, whereby surface features were described and compared. The elemental composition was analyzed by EDS. According to surface analysis, groups ABZ and RL showed a homogeneous surface, with better finishing, whereas the surfaces in groups NF and RM were rougher. The chemical components with the highest percentage were Fe, Cr and C. Groups NF and MR showed no nickel in their composition. In conclusion, the bracket surface of the ABZ and RL groups was more homogeneous, with grooves and pores, whereas the surfaces in groups NF and RM showed numerous flaws, cracks, pores and grooves. The chemical composition analysis confirmed that the nickel-free brackets had no Ni in their composition, as confirmed by the manufacturers specifications, and were therefore safe to use in patients with a medical history of allergy to this metal.

Avaliação cefalométrica do efeito do tratamento da má oclusão Classe II, divisão 1, com o bionator de Balters: estudo com implantes metálicos

AIM: to evaluate the bionator treatment effect on Class II, division 1, malocclusion, presenting mandibular retrusion or mandibular length deficiency. METHODS: it is described the effects of the treatment in three patients that were accompanied with no treatment for one year and them were treated for two years with bionator. In all three patients metallic implants were inserted to serve as reference to cephalometric tracing superimposition that, together with some traditional cephalometric measurements, generated data to the evaluation of the orthopedic and orthodontic effects of Class II malocclusion treatment with this appliance. RESULTS AND CONCLUSIONS: it was observed a maxillary growth restriction and a stimulus of mandibular growth as well as a change in the direction of condylar growth. There was also an uprighting of the upper incisors and in the lower arch Balters bionator increased the natural tendency of buccal movement of the incisors.

Avaliação transversal e vertical da maxila, após expansão rápida, utilizando um método de padronização das radiografias póstero-anteriores

Objetivo: na presente pesquisa utilizou-se o aparelho Hyrax tendo como objetivo avaliar as alteracoes transversais e verticais da maxila. Foram selecionados 20 pacientes de ambos os generos, entre 7 e 11 anos de idade, que apresentavam mordida cruzada posterior uni ou bilateral. Metodologia: foram realizadas telerradiografias em norma frontal (PA) antes e apos a expansao. A fim de evitar que a falta de padronizacao dessas radiografias pudesse influenciar nos resultados, idealizou-se um metodo de padronizacao para tais radiografias. Resultados e Conclusoes: os resultados mostraram que a correcao da mordida cruzada posterior com o aparelho Hyrax, que ocorreu em todos os casos, foi em funcao tanto da abertura da sutura palatina mediana como tambem da inclinacao dos molares. A medida JgE-JgD relacionada com a expansao maxilar aumentou significantemente em todos os casos tratados. Nas avaliacoes dentarias, as medidas verticais nao apresentaram diferencas significantes, ao contrario das medidas transversais (FTEFTD; FBE-FBD; LO.BTE; LO.BTD; BTE.BTD). A largura da cavidade nasal tambem aumentou significantemente (CNE-CND). O metodo de padronizacao proposto permite, portanto, utilizar as medidas que avaliam a expansao rapida da maxila, atraves das radiografias postero-anteriores, com seguranca, tambem no sentido vertical. Resumo