Marco Antonio de Oliveira Almeida

Stability of the palatal rugae as landmarks for analysis of dental casts

The aims of this study were to determine if the palatal rugae are stable during normal growth, and whether treatment with either headgear or functional appliances affects the position of the rugae. Initial and 15-month recall dental casts of 94 patients enrolled in a study of early Class II treatment were evaluated. The children had been randomly assigned to one of three groups: control (n = 34), headgear (n = 30), and functional appliance (n = 30). Landmarks on the palatal raphe and palatal rugae were recorded using the Reflex Metrograph. A median palatal plane was constructed using the digitized raphe points as reference. Offsets from this plane to the ruga points and transverse and anteroposterior linear distances between ruga points were obtained for all casts. Transverse offsets and linear distances between medial points of the first rugae and the anteroposterior distances between the medial points of the second and third rugae did not show statistically significant changes in all groups. Significant changes were observed for the lateral points of the rugae, particularly in the headgear group. The medial rugae appear to be suitable anatomic points for the construction of stable reference planes for longitudinal cast analysis.

Stability of the palatal rugae as landmarks for analysis of dental casts in extraction and nonextraction cases

To determine whether the positions of the palatal rugae were affected by orthodontic therapy, pre- and posttreatment maxillary dental casts of 57 adult patients treated in the graduate orthodontic clinic at the University of North Carolina were evaluated. The orthodontic extraction group (n = 27) was composed of patients whose treatment included the extraction of two maxillary premolars. The remaining patients (n = 30) had been treated without extractions. Transverse changes observed over time were significantly different from zero only for the medial points of the first rugae in the nonextraction group and for the lateral points of the first rugae in the extraction group. None of the changes observed in the transverse measures were statistically different between the two groups. In the extraction group, there were significant anteroposterior changes in the right lateral points between the first and second rugae and between the second and third rugae, and in the right medial points between the second and third rugae. There were no statistically significant anteroposterior changes observed in the nonextraction group over time. When the two groups were compared, the average distance between the lateral first and second right rugae, and the average distance between the lateral second and third right rugae were significantly different. The medial and lateral points of the third rugae appear to be stable landmarks for the construction of anatomic reference pints in longitudinal cast analysis.

Direct bonding to porcelain

Orthodontic brackets were bonded to 180 faces of 45 porcelain cubes that were divided into three groups according to their surface preparation. In group I, the glaze had been removed with a sandpaper disk, whereas in group II, it was maintained. A solution of acidulated phosphate fluoride (APF) gel was applied to the samples in groups I and II for 5 minutes after pumicing. In group III, the glaze had been removed with a coarse diamond bur. Each group was further divided into four subgroups, depending on whether a priming agent had been used, and the type of composite used to bond the brackets. Shear force was used to debond the brackets, and the results showed that the APF solution was unable to provide enough retention on porcelain surface to bond brackets. Mechanical retention, obtained with a coarse diamond bur, was necessary to increase bond strength, which can be further improved by chemical bonding, with a silane priming agent. Therefore bonding to porcelain is clinically possible and is an acceptable procedure in orthodontic treatment.

Oral health-related quality of life and orthodontic treatment seeking

INTRODUCTION The aim of this study was to assess oral health-related quality of life (OHQOL) in adolescents who sought orthodontic treatment. A comparison between these adolescents and their age-matched peers who were not seeking orthodontic treatment provided an assessment of the role of OHQOL in treatment seeking. METHODS The sample consisted of 225 subjects, 12 to 15 years of age; 101 had sought orthodontic treatment at a university clinic (orthodontic group), and 124, from a nearby public school, had never undergone or sought orthodontic treatment (comparison group). OHQOL was assessed with the Brazilian version of the short form of the oral health impact profile, and malocclusion severity was assessed with the index of orthodontic treatment need. RESULTS Simple and multiple logistic regression analysis showed that those who sought orthodontic treatment reported worse OHQOL than did the subjects in the comparison group (P <0.001). They also had more severe malocclusions as shown by the index of orthodontic treatment need (P = 0.003) and greater esthetic impairment, both when analyzed professionally (P = 0.008) and by self-perception (P <0.0001). No sex differences were observed in quality of life impacts (P = 0.22). However, when the orthodontic group was separately evaluated, the girls reported significantly worse impacts (P = 0.05). After controlling for confounding (dental caries status, esthetic impairment, and malocclusion severity), those who sought orthodontic treatment were 3.1 times more likely to have worse OHQOL than those in the comparison group. CONCLUSIONS Adolescents who sought orthodontic treatment had more severe malocclusions and esthetic impairments, and had worse OHQOL than those who did not seek orthodontic treatment, even though severely compromised esthetics was a better predictor of worse OHQOL than seeking orthodontic treatment.

Clinical comparison between a glass ionomer cement and a composite for direct bonding of orthodontic brackets

The clinical performance of a glass ionomer cement for direct bonding of orthodontic brackets was compared with a composite resin routinely used in this procedure. Brackets were bonded, using both materials, in alternate quadrants of 16 patients of the Orthodontic Clinic of the State University of Rio de Janeiro. A total of 225 teeth, 112 in the glass ionomer cement group and 113 in the composite group, were tested. Bond failure frequencies were recorded for 12 months, and chi-square statistical test was carried out comparing the failure rates of the materials. The composite showed a statistically significant lower failure rate (7.96%) than the glass ionomer cement (50.89%), regardless of the dental arch tested. Although the glass ionomer cement presents important properties not observed in the composite, it is necessary to increase its cohesive strength to permit its clinical use for direct bonding of orthodontic brackets.

Prediction of mesiodistal diameter of unerupted lower canines and premolars using 45° cephalometric radiography

Abstract The reliability of using the oblique cephalometric radiograph for early prediction of the mesiodistal widths of unerupted lower canines and premolars was investigated. Mandibular models and oblique cephalometric radiographs were obtained for 40 Brazilian children (20 boys and 20 girls), in the mixed dentition phase. Further models were obtained for the same sample when all permanent teeth had erupted. A Student t test showed statistically significant differences of tooth size between the sexes but not between right and left sides. Measurements of the unerupted canines and premolars taken from the 45° cephalometric radiograph were statistically greater than the actual values, although a high correlation was observed between them. Linear regression equations and correction tables were established to compensate for this magnification. The actual values for these teeth were compared with the corrected predicted values from the 45° radiograph and with the predicted values obtained from the methods of Ballard and Wylie, 5 Carey 7 Moyers 9 and Tanaka and Johnston. 11 A high correlation was observed only between the actual values and the corrected predicted values from the radiograph. The results indicate that, correcting the magnification, the 45° cephalometric radiographic may be used in predicting unerupted lower canine and premolar widths in Brazilian children. (A M J O RTHOD D ENTOFAC O RTHOP 1995;107:309-14.)

Soft tissue response to mandibular advancement using 3D CBCT scanning

This prospective longitudinal study assessed the 3D soft tissue changes following mandibular advancement surgery. Cranial base registration was performed for superimposition of virtual models built from cone beam computed tomography (CBCT) volumes. Displacements at the soft and hard tissue chin (n = 20), lower incisors and lower lip (n = 21) were computed for presurgery to splint removal (4-6-week surgical outcome), presurgery to 1 year postsurgery (1-year surgical outcome), and splint removal to 1 year postsurgery (postsurgical adaptation). Qualitative evaluations of color maps illustrated the surgical changes and postsurgical adaptations, but only the lower lip showed statistically significant postsurgical adaptations. Soft and hard tissue chin changes were significantly correlated for each of the intervals evaluated: presurgery to splint removal (r = 0.92), presurgery to 1 year postsurgery (r = 0.86), and splint removal to 1 year postsurgery (r = 0.77). A statistically significant correlation between lower incisor and lower lip was found only between presurgery and 1 year postsurgery (r = 0.55). At 1 year after surgery, 31% of the lower lip changes were explained by changes in the lower incisor position while 73% of the soft tissue chin changes were explained by the hard chin. This study suggests that 3D soft tissue response to mandibular advancement surgery is markedly variable.

Three-dimensional assessment of mandibular advancement 1 year after surgery

INTRODUCTION This prospective observational study evaluated changes in the 3-dimensional position and remodeling of the mandibular rami, condyles, and chin at splint removal and 1 year after mandibular advancement surgery. METHODS Presurgery, splint removal (4-6 weeks postsurgery), and 1-year postsurgery cone-beam computed tomography scans of 27 subjects were used. Superimposition on the cranial base was used to assess positional or remodeling changes in the anatomic regions of interest. Surface distance displacements were visually displayed and quantified by 3-dimensional color maps. A 1-sample t test was used to assess the average postsurgical changes of each region of interest. The level of significance was set at 0.05. RESULTS After antero-inferior chin displacement with surgery (mean, 6.81 +/- 3.2 mm at splint removal), the average 1-year postsurgery displacement was not statistically significant (P = 0.44). Postsurgical adaptations greater than 2 mm were observed in 48% of the patients: 16% with an additional anterior-inferior displacement of the chin of 2 to 4 mm, and 4% with >or= 4 mm; 20% had postero-superior movement of 2 to 4 mm, and 8% had postero-superior movement of >or= 4 mm. The condyles tended to move, on average, <or= 2 mm supero-posteriorly with surgery, and this small positional displacement was maintained 1 year postsurgery (right condyle, P = 0.58; left, P = 0.88). The rami exhibited outward (lateral) movements with surgery, with greater displacement of the inferior part of the rami (2 mm in 65% of the subjects). This torque of the ramus with surgery was stable 1 year postsurgery. CONCLUSIONS Three-dimensional assessment of skeletal changes with mandibular advancement surgery shows that nearly half of the patients have >2 mm change in chin position from splint removal to the 1-year follow-up, with approximately equal chances of anterior and posterior movement. Torque of the rami usually occurs with mandibular advancement surgery.

Three-dimensional regional displacements after mandibular advancement surgery: one year of follow-up.

PURPOSE To evaluate the association of 3-dimensional changes in the position of the condyles, rami, and chin at splint removal and 1 year after mandibular advancement surgery. PATIENTS AND METHODS This prospective observational study used preoperative and postoperative scans of 27 subjects presenting with a skeletal Class II jaw relationship with a normal or deep overbite. An automatic technique of cranial base superimposition was used to assess the positional and/or remodeling changes in the anatomic regions of interest. The displacements were visually displayed and quantified using 3-dimensional color maps. The positive and negative values of surface distances in the color maps indicated the direction of the displacements. Pearson correlation coefficients and a linear model for correlated data were used to evaluate the association between the regional displacements. RESULTS The postoperative adaptations in the chin position between splint removal and 1 year after surgery were significantly negatively correlated with changes in the borders of the posterior ramus (left, r = -0.73, P ≤ .0001; and right, r = -0.68, P = .00) and the condyles (left, r = -0.53, P = .01; and right, r = -0.46, P = .02), indicating that these structures tended to be displaced in the same direction. Even though the mean condylar displacement with surgery was less than 1 mm, individual displacements greater than 2 mm with surgery were observed for 24% of the condyles. The condylar displacements were maintained at 1 year after surgery for 17% of the condyles. CONCLUSIONS The surface distance displacements indicated that the postoperative adaptations at different anatomic regions were significantly related.

A systematic review of etiological and risk factors associated with bruxism

Objective The aim of the present work was to systematically review the literature and identify all peer-reviewed papers dealing with etiological and risk factors associated with bruxism. Data sources Data extraction was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for randomized clinical trials (RCT), controlled clinical trials (CCT) or cohort studies: Cochrane Library, Medline, and Embase from 1980 to 2011. Unpublished literature was searched electronically using ClinicalTrials.gov. Data selection The primary outcome was bruxism etiology. Studies should have a standardized method to assess bruxism. Data extraction Screening of eligible studies, assessment of the methodological quality and data extraction were conducted independently and in duplicate. Two reviewers inspected the references using the same search strategy and then applied the same inclusion criteria to the selected studies. They used criteria for methodological quality that was previously described in the Cochrane Handbook. Among the 1247 related articles that were critically assessed, one randomized clinical trial, one controlled clinical trial and seven longitudinal studies were included in the critical appraisal. Of these studies, five were selected, but reported different outcomes. Data synthesis There is convincing evidence that (sleep-related) bruxism can be induced by esophageal acidification and also that it has an important relationship with smoking in a dose-dependent manner. Disturbances in the central dopaminergic system are also implicated in the etiology of bruxism.