Bond Strength of Metallic or Ceramic Orthodontic Brackets to Enamel, Acrylic, or Porcelain Surfaces.

Bonding strategies within different brackets and dental materials are still a challenge concerning adhesion and dental surface damage. This study compared the shear and tensile bond strength of orthodontic ceramic and metallic brackets to enamel, acrylic, and ceramic surfaces after thermal cycling. Dental surfaces were divided into three groups: enamel, ceramic, and acrylic. Each group received stainless-steel and ceramic brackets. After thermal cycling, specimens were randomly divided into two subgroups considering tensile (TBS) or shear bond strength (SBS) test. After the mechanical testing, scanning electron and optical microscopy were performed, and the adhesive remnant index (ARI) was determined. The two-way ANOVA full factorial design was used to compare TBS, SBS, and ARI on the surface and bracket type (α = 0.05). There were significant differences in TBS, SBS, and ARI values per surface (p < 0.001 and p = 0.009) and type of bracket (p = 0.025 and p = 0.001). The highest mean SBS values were recorded for a ceramic bracket bonded to an acrylic surface (8.4 ± 2.3 MPa). For TBS, a ceramic bracket bonded to acrylic showed the worst performance (5.2 ± 1.8 MPa) and the highest values were found on a metallic bracket bonded to enamel. The adhesion of metallic or ceramic brackets is enough for clinical practice although the damage of the enamel surface after debonding is irreversible and harmful for the aesthetic outcome of the teeth.

Integrating piezoresistive sensors on the embouchure analysis of the lower lip in single reed instrumentalists: implementation of the lip pressure appliance (LPA).

Background: It is essential to understand, characterize, and measure the embouchure mechanism of a wind instrumentalists, where the applied forces on the perioral tissues can usually promote discomfort or pain. Methods: The sample consisted of five clarinet players and five saxophone players. The embouchure force measurements at the lower lip area were assessed using a piezoresistive sensor (FlexiForceTM, Tekscan, Boston, USA, 0.07 kgf/cm2) placed on the lower part of the mouthpiece of the single reed instrument. Furthermore, each participant performed three times three different notes at different pitches: high, medium, and low. An intraoral device was manufactured in order to dissipate the existing pressures. Results: The piezoresistive sensors applied to the mouthpiece of the five clarinetists presented values between 16 and 226 g of force. In the case of the five saxophonists, the values registered were between 5 and 320 g of force. Conclusions: Piezoresistive sensors are a valid option to characterize that single reed instrumentalists apply substantial forces at the lower lip that can be equivalent to medium orthodontic forces. The implementation of the Lip Pressure Appliance can be a valid solution on the prevention of eventual lesions resulting from the embouchure forces.

Thermographic Study of the Orofacial Structures Involved in Clarinetists Musical Performance.

INTRODUCTION: Wind instrumentalists like clarinetists, may present a muscular hyperactivity on certain groups of the cranio-cervico-mandibular complex, due to their musical activity. Therefore, the use of infrared thermography can be used to assess and characterize the orofacial structures involved in clarinet performance. AIM: The objective of this study was to analyze and record the thermal patterns using the thermographic camera Flir® E60sc to evaluate anatomically and physiologically certain orofacial structures of the cranio-cervical-mandibular complex, such as the masticatory muscles and the region of the temporomandibular joint. METHODOLOGY: A sample of 30 clarinetists completed an individual questionnaire composed of two components (musical and clinical history of the participant), and were subjected to a clinical examination. Four thermographic images were taken of the cranio-cervical-mandibular complex at a rest position with frontal, right lateral, left lateral and anterior dentoalveolar components views. Each musician performed a piece of music for an uninterrupted period of 10 min. New thermographic images were captured with the same incidences, after the performance, respecting the same protocol. RESULTS: There were statistically significant differences in the areas corresponding to the left temporal muscle, the orbicularis muscle (labial component), the left and right perioral teguments, as well as in the upper central incisors. There was also statistical evidence regarding the initial and final temperature asymmetries regarding temporal muscle and orbicular muscles (labial and marginal components). CONCLUSION: Infrared thermography has been shown to be an effective complementary diagnostic tool in the monitorization of the cranio-cervical-mandibular complex of clarinetists.

How to Achieve Facial Balance by Mandibular Contouring Ostectomy in Hemimandibular Hyperplasia.

Hemimandibular hyperplasia is a rare type of condylar hyperplasia which leads to facial asymmetry. Its surgical correction may be challenging since it usually requires complex mandibular osteotomies. Mandibular inferior border ostectomy is poorly described in the literature. The aim of this report is to present a new surgical technique guided by a customized surgical splint manufactured using computer-aided design/computer-aided manufacturing technology. Very good aesthetic results are achieved as it is very precise.

Different manifestations of Class II Division 2 incisor retroclination: a morphologic study.

INTRODUCTION: The aims of this study were to investigate whether there is a different transverse morphologic pattern of dental arches among patients with different manifestations of Class II Division 2 incisor retroclination and to evaluate to what extent the pattern of smaller-than-average teeth in Class II Division 2 malocclusion is common to all groups studied. This information might clarify whether different Class II Division 2 phenotypes represent a single etiology or multiple etiologies. METHODS: The sample comprised 108 subjects with Class II Division 2 malocclusions, divided into 2 groups according to the type of incisor retroclination: group I included 43 Class II Division 2 subjects with retroclination exclusively of the maxillary central incisors, and group II included 65 Class II Division 2 subjects with retroclination of the 4 maxillary incisors. Maxillary and mandibular intercanine and intermolar widths as well as mesiodistal crown dimensions of the 4 maxillary and mandibular incisors were determined from the patients' initial study models. Mean values of all variables were compared between the 2 groups by sex with analysis of variance. RESULTS: From the comparison between these 2 groups, no statistically significant differences were found for all transverse measurements (P >0.05). For all mesiodistal measurements analyzed, statistically significant differences between the groups were only found for the mean value of both maxillary lateral incisors' mesiodistal dimensions in both sexes (P <0.05). CONCLUSIONS: It is not possible to attribute a characteristic pattern of dental arch-width and incisor mesiodistal dimensions to the different manifestations of incisor retroclination in Class II Division 2 malocclusion.