Grace Viana

Relationship between rapid maxillary expansion and nasal cavity size and airway resistance: Short- and long-term effects

INTRODUCTION The availability of new, reliable, objective, and 3-dimensional techniques to assess the effects of rapid maxillary expansion on the morphology of the maxillary dental arch, nasal cavity dimensions, and nasal airway resistance led to the development of this research. METHODS Thirty-eight subjects participated in this study (mean age, 13 years). Data were collected before expansion, when the expander was stabilized, when the expander was removed, and 9 to 12 months after the expander was removed. Subjective assessment of improvement in nasal respiration was obtained when the expander was stabilized. Three-dimensional imaging and acoustic rhinometry were used to assess the virtual cast and the nasal cavity, respectively. RESULTS AND CONCLUSIONS The statistically significant short-term effects of RME were (1) mean increases in palatal area, volume, and intermolar distance; (2) a mean reduction of nasal airway resistance; and (3) mean increases in total nasal volume and nasal valve area. Our long-term findings were the following: (1) mean palatal area and intermolar distance were reduced, while palatal volume was stable, and (2) nasal airway resistance was stable, whereas mean nasal cavity volume and minimal cross-sectional area increased. Additionally, 61.3% of our subjects reported subjective improvement in nasal respiration. Weak correlations were found between all variables analyzed.

Preferences for facial profiles between Mexican Americans and Caucasians.

The objective of this study was to determine differences between Mexican American and Caucasian judges in the acceptability of lip protrusion in computer animations of two male and two female persons of Mexican descent. Thirty Caucasians and 30 Mexican Americans of varying age, sex, education, and level of acculturation responded to facial profile computer animations that moved lips from an extreme protrusive to an extreme retrusive position. Judges were asked to complete two tasks: (1) to press the mouse button when the image was perceived to be most pleasing (MP) and (2) to determine the boundaries of a zone of acceptability (ZA) of lip protrusion by pressing the mouse button when the moving image became acceptable and releasing it when the image of the protrusion became unacceptable. In general, Mexican Americans preferred upper or lower lip positions to be less protrusive than did Caucasians. Larger mean ZAs for both upper and lower lip positions with male computer animation images and lower lip position for female computer animation images were found among Caucasians when compared with low-acculturated Mexican Americans. A significant mean difference in midpoint of acceptability (MA) for lip position between Caucasians and low-acculturated Mexican Americans was observed for both upper and lower lip position with female computer animation images.

Influence of Attachments and Interproximal Reduction on the Accuracy of Canine Rotation with Invisalign

OBJECTIVE To evaluate the influence of attachments and interproximal reduction on canines undergoing rotational movement with Invisalign. MATERIALS AND METHODS In this prospective clinical study, 53 canines (33 maxillary and 20 mandibular) were measured from the virtual TREAT models of 31 participants treated with anterior Invisalign. The pretreatment virtual model of the predicted final tooth position was superimposed on the posttreatment virtual model using ToothMeasure, Invisaligns proprietary measurement software. A one-way analysis of variance (ANOVA) (P < .05) compared three treatment modalities: attachments only (AO), interproximal reduction only (IO), and neither attachments nor interproximal reduction (N). Students t-tests (P < .05) compared the mean accuracy of canine rotation between arches. RESULTS The mean accuracy of canine rotation with Invisalign was 35.8% (SD = 26.3). Statistical analyses indicated that there was no significant difference in accuracy between groups AO, IO, and N (P = .343). There was no statistically significant difference (P = .888) in rotational accuracy for maxillary and mandibular canines for any of the treatment groups. The most commonly prescribed attachment shape was the vertical-ellipsoid (70.5%). CONCLUSIONS Vertical-ellipsoid attachments and interproximal reduction do not significantly improve the accuracy of canine rotation with the Invisalign system.

Solubility study of phytochemical cross-linking agents on dentin stiffness

OBJECTIVES The effects of interactions between cross-linking proanthocyanidins (PA) in polar solvents and type-I collagen of demineralized dentin were investigated. METHODS Three PA-rich extracts, two from grape seed (GSEP and GSES) and one from cocoa (COE), were dissolved (water, ethanol:water and acetone:water) and analyzed for their ability to increase the modulus of elasticity of demineralized dentin. Sound dentin beams (0.5mmx1.7mmx7mm) were fully demineralized and divided into 12 groups according to the type of cross-linking agent and solvents used. Specimens were immersed in the respective solutions and tested at baseline, 10, 30, 60, 120 and 240min. RESULTS The elastic modulus (EM) of dentin was significantly increased by the PA treatment regardless of time (p<0.05 for all times). The extracts showed different solubility in different solvents. GSEP showed the highest increase in EM when diluted in distilled water and acetone at all exposure times. Both GSEs showed superior results when diluted in distilled water and after 4h of treatment, while COE produced strongest enhancement when dissolved in ethanol:water. CONCLUSIONS The results indicates that herbal extraction process and other pharmacognostic parameters have an important influence on extract solubility as well as constitution and, consequently, on the PA-dentin matrix interaction.

Long-term effects of orthodontic therapy on the maxillary dental arch and nasal cavity

INTRODUCTION Rapid maxillary expansion (RME) can enlarge the maxillary dental arch while increasing nasal cavity volume and nasal valve area, and decreasing upper airway resistance over time. However, the long-term effects of RME on arch morphology and nasal cavity geometry in patients treated with RME compared with the general population are unclear. METHODS Three-dimensional morphometic analysis and acoustic rhinometry were used to evaluate the maxillary dental arches and nasal cavities in a post-RME-treatment group (n = 25) and a control group (n = 25). RESULTS Palatal area and volume increased substantially after expansion and remained stable until posttreatment. Small increases in intermolar distance were not significant between the time points. Nasal airway resistance significantly decreased after RME and remained stable until posttreatment. Nasal cavity volume was stable during expansion and posttreatment. It increased significantly during expander stabilization and 9-12 months after expander removal. The minimal cross-sectional area significantly increased between the end of expansion and expander removal and remained stable until posttreatment. All measurements were comparable with those of the matched controls at posttreatment except for palatal area, which was smaller in the treatment group. CONCLUSIONS RME is a powerful tool to normalize most of the variables investigated. Edgewise orthodontic treatment and a retention regimen that consisted of maxillary circumferential or traditional Hawley retainers met satisfactory standards to stabilize the achieved outcomes. Future studies should include morphometric, functional, and skeletal analyses so that the effects of growth and remodeling are better elucidated.

Measuring Progressive Soft Tissue Change With Nasoalveolar Molding Using a Three-dimensional System

Background: For craniofacial orthodontics and surgery to progress, accurate temporal evaluation of soft tissue and skeletal change with treatment is necessary. Evolution in three-dimensional imaging eliminates certain inherent challenges in making such measurements in infants with facial clefts. Objective: The aim of this pilot study was to measure progressive three-dimensional changes in nasal form in a series of infants with facial clefts during the course of presurgical nasoalveolar molding. Materials and Methods: In 5 infants with unrepaired cleft lip and palate, three-dimensional photographs were obtained using the 3dMD system (3dMD, Inc, Atlanta, GA) at 2-week intervals during nasoalveolar molding treatment. Using the 3dMD Vultus software, temporal soft tissue changes were evaluated quantitatively based on three-dimensional linear measurements of 3 landmarks in the nasal area and qualitative changes in the surface shell. Results: Increase in columellar length on the cleft side and decrease of the nostril floor on the noncleft side were observed in all subjects. Progressive changes were observed most significantly in week 4 (T3) into treatment. Conclusions: This pilot study describes an approach using the 3dMD photo system with Vultus software for measuring the progressive change in the nasal soft tissues. The 3dMD system was believed to be valuable for facial analysis in this setting.

3D evaluation of palatal rugae for human identification using digital study models.

Background: While there is literature suggesting that the palatal rugae could be used for human identification, most of these studies use two-dimensional (2D) approach. Aim: The aims of this study were to evaluate palatal ruga patterns using three-dimensional (3D) digital models; compare the most clinically relevant digital model conversion techniques for identification of the palatal rugae; develop a protocol for overlay registration; determine changes in palatal ruga individual patterns through time; and investigate the efficiency and accuracy of 3D matching processes between different individuals’ patterns. Material and Methods: Five cross sections in the anteroposterior dimension and four cross sections in the transverse dimension were computed which generated 18 2D variables. In addition, 13 3D variables were defined: The posterior point of incisive papilla (IP), and the most medial and lateral end points of the palatal rugae (R1MR, R1ML, R1LR, R1LL, R2MR, R2ML, R2LR, R2LL, R3MR, R3ML, R3LR, and R3LL). The deviation magnitude for each variable was statistically analyzed in this study. Five different data sets with the same 31 landmarks were evaluated in this study. Results: The results demonstrated that 2D images and linear measurements in the anteroposterior and transverse dimensions were not sufficient for comparing different digital model conversion techniques using the palatal rugae. 3D digital models proved to be a highly effective tool in evaluating different palatal ruga patterns. The 3D landmarks showed no statistically significant mean differences over time or as a result of orthodontic treatment. No statistically significant mean differences were found between different digital model conversion techniques, that is, between OrthoCAD™ and Ortho Insight 3D™, and between Ortho Insight 3D™ and the iTero® scans, when using 12 3D palatal rugae landmarks for comparison. Conclusion: Although 12 palatal 3D landmarks could be used for human identification, certain landmarks were especially important in the matching process and were arranged by strength and importance. Proposed values for 3D palatal landmarks were introduced that could be useful in biometrics and forensic odontology for the verification of human identity.

The effectiveness of Oraqix versus TAC(a) for placement of orthodontic temporary anchorage devices

OBJECTIVE To test the hypothesis that there is no difference in the actions and effectiveness of topical anesthetics TAC Alternate (TAC((a))) and Oraqix in placing temporary anchorage devices (TADs). MATERIALS AND METHODS Each topical anesthetic was placed on opposing sides in the maxilla or mandible using blinded applicators for 3-9 minutes followed by the TAD placement. A total of 21 patients ranging from 10-25 years old were studied. During the procedure the primary investigator (PI) used the sound, eye, and motor scale to measure the movements elicited by the patient. The PI also noted the time taken for the topical anesthetic to be effective and the amount that was applied. Following the placement of the TADs, the patients were given the Wong-Baker FACES Scale and the Visual Analog Scale to rate the degree of discomfort. The nonparametric Wilcoxon signed-rank test was used to test the effectiveness of the treatments based on the three ordinal scales, the dosage, and the onset time. RESULTS The time it took for the TAC((a)) to provide adequate anesthesia averaged 4.43 minutes and for Oraqix the time was 6.33 minutes (P = .00). The minimum dosage of TAC((a)) to provide adequate anesthesia averaged 0.25 mL, and for Oraqix the minimum dosage averaged 0.31 mL (P = .00). CONCLUSIONS The hypothesis was rejected. TAC((a)) was more effective than Oraqix in placing TADs with a recommended dose of 0.20-0.30 mL and a minimum application time of 3 minutes.

Comparison of the transformation temperatures of heat-activated Nickel-Titanium orthodontic archwires by two different techniques.

OBJECTIVES The purpose of this study was to investigate the suitability of the Bend and Free Recovery (BFR) method as a standard test method to determine the transformation temperatures of heat-activated Ni-Ti orthodontic archwires. This was done by determining the transformation temperatures of two brands of heat-activated Ni-Ti orthodontic archwires using the both the BFR method and the standard method of Differential Scanning Calorimetry (DSC). The values obtained from the two methods were compared with each other and to the manufacturer-listed values. METHODS Forty heat-activated Ni-Ti archwires from both Rocky Mountain Orthodontics (RMO) and Opal Orthodontics (Opal) were tested using BFR and DSC. Round (0.016 inches) and rectangular (0.019×0.025 inches) archwires from each manufacturer were tested. The austenite start temperatures (As) and austenite finish temperatures (Af) were recorded. RESULTS For four of the eight test groups, the BFR method resulted in lower standard deviations than the DSC method, and, overall, the average standard deviation for BFR testing was slightly lower than for DSC testing. Statistically significant differences were seen between the transformation temperatures obtained from the BFR and DSC test methods. However, the Af temperatures obtained from the two methods were remarkably similar with the mean differences ranging from 0.0 to 2.1°C: Af Opal round (BFR 26.7°C, DSC 27.6°C) and rectangular (BFR 27.6°C, DSC 28.6°C); Af RMO round (BFR 25.5°C, DSC 25.5°C) and rectangular (BFR 28.0°C, DSC 25.9°C). Significant differences were observed between the manufacturer-listed transformation temperatures and those obtained with BFR and DSC testing for both manufacturers. SIGNIFICANCE The results of this study suggest that the Bend and Free Recovery method is suitable as a standard method to evaluate the transformation temperatures of heat-activated Ni-Ti orthodontic archwires.

Effect of prophylactic pastes containing active ingredients on the enamel-bracket bond strength of etch-and-rinse and self-etching systems.

OBJECTIVE To evaluate the effect of prophylactic pastes containing active ingredients such as amorphous calcium phosphate (ACP), fluoride, or a combination of both on the enamel-bracket tensile bond strength. MATERIALS AND METHODS Human molars were randomly divided into four groups (N = 40) according to the type of prophylactic pastes: control (no active ingredients), paste containing fluoride, paste containing ACP, and paste containing both fluoride and ACP. After prophylaxis, 20 brackets per group were bonded using an etch-and-rinse bonding technique (37% phosphoric acid and Ortho solo), and the other remaining 20 brackets were bonded using a self-etch bonding technique (Clearfil S(3)Bond). Samples were tested for tensile strength 24 hours after bonding using a universal testing machine. Data were analyzed using analysis of variance (ANOVA) and Students t-test with significance level at .05. RESULTS The mean tensile bond strength varied between 3.043 (ACP) and 9.232 (control) MPa. The etch-and-rinse bonding technique was significantly affected by pastes containing active ingredients (P < .001). The self-etching system was not significantly affected by different pastes (P > .05). CONCLUSIONS Cleaning enamel surfaces with prophylactic pastes that contain ACP and/or fluoride, prior to orthodontic bonding, resulted in a statistically significant decrease in the tensile bond strength of etch-and-rinse bonding technique.