Giseon Heo

Transverse, vertical, and anteroposterior changes from bone-anchored maxillary expansion vs traditional rapid maxillary expansion: A randomized clinical trial

INTRODUCTION The purpose of this study was to compare the transverse, vertical, and anteroposterior skeletal and dental changes in adolescents receiving expansion treatment with tooth-borne and bone-anchored expanders. Immediate and long-term changes were measured on cone-beam computed tomography (CBCT) images. METHODS Sixty-two patients needing maxillary expansion were randomly allocated to 1 of 3 groups: traditional hyrax tooth-borne expander, bone-anchored expander, and control. CBCT images were taken at baseline, immediately after expansion, after removal of the appliance (6 months), and just before fixed bonding (12 months). Repeated measures multivariate analysis of variance (MANOVA) was applied to the distances and angles measured to determine the statistical significance in the immediate and long time periods. Bonferroni post-hoc tests were used to identify significant differences between the treatment groups. RESULTS Immediately after expansion, the subjects in the tooth-borne expander group had significantly more expansion at the crown level of the maxillary first premolars (P = 0.003). Dental crown expansion was greater than apical expansion and skeletal expansion with both appliances. The control group showed little change (growth) over the 6-month interval. At 12 months, no group had a statistically significant difference in angle changes, suggesting symmetric expansion. Both treatment groups had significant long-term expansion at the level of the maxillary first molar crown and root apex, first premolar crown and root, alveolus in the first molar and premolar regions, and central incisor root. Tooth-borne expansion resulted in significantly more long-term expansion at the maxillary premolar crown and root than did bone-borne expansion. CONCLUSIONS Both expanders showed similar results. The greatest changes were seen in the transverse dimension; changes in the vertical and anteroposterior dimensions were negligible. Dental expansion was also greater than skeletal expansion.

Three-dimensional orthodontic force measurements

INTRODUCTION Until recently, much of the orthodontic biomechanics literature was restricted to 2-dimensional experimental studies and, more recently, to assumption-based 3-dimensional computer modeling. There is little evidence in the literature regarding 3-dimensional experimental measurements and analysis of orthodontic force systems. METHODS The purpose of this study was the design, construction, and validation of a laboratory-based human mouth model capable of accurately measuring forces and moments applied by orthodontic fixed appliances on all teeth in 1 arch. A high canine malocclusion was simulated, and forces and moments acting on the canine, lateral incisor, and premolar were measured with passive and conventional ligation. RESULTS We were successful in building this human mouth model. The error in force measurements of the 14 transducers was 1.54%. The force system resulting from passive ligation brackets was considerably different from that of conventional ligation. CONCLUSIONS This method will allow us, for the first time in the history of our specialty, to determine with great accuracy the forces acting on orthodontically treated teeth. Future research will focus on simulating many types of orthodontic clinical applications of full-fixed or partial-fixed appliances.

Torque expression of self-ligating brackets

INTRODUCTION The labiolingual inclination of maxillary and mandibular incisors is considered by many orthodontists to be an important determinant of pleasing dental esthetics and ideal stable occlusion. In contemporary fixed appliances, attaching a rectangular orthodontic archwire to a bracket with a rectangular slot makes third-order control possible. The purpose of this study was to measure the difference in third-order moments that can be delivered by engaging 0.019 x 0.025-in stainless steel archwires to 2 active self-ligating brackets (In-Ovation, GAC, Bohemia, NY; Speed, Strite Industries, Cambridge, Ontario, Canada) and 2 passive self-ligating brackets (Damon2, Ormco, Orange, Calif; Smart Clip, 3M Unitek, Monrovia, Calif). METHODS A bracket/wire assembly torsion device was developed. This novel apparatus can apply torsion to the wire while maintaining perfect vertical and horizontal alignment between the wire and the bracket. A multi-axis force/torque transducer was used to measure the moment of the couple (torque), and a digital inclinometer was used to measure the torsion angle. Fifty maxillary right central incisor brackets from each of the 4 manufacturers were tested. RESULTS There was a significant difference in the engagement angle between the 2 types of brackets; on average, torque started to be expressed at 7.5 degrees of torsion for the active self-ligating brackets and at 15 degrees of torsion for the passive self-ligating brackets. The torque expression was higher for the active self-ligating brackets up to 35 degrees of torsion. Torsion of the wire past this point resulted in a linear increase of the measured torque for the Damon2, the Smart Clip, and the In-Ovation brackets. The torque was relatively constant past 35 degrees of torsion for the Speed bracket. CONCLUSIONS We conclude that active self-ligating brackets are more effective in torque expression than passive self-ligating brackets.

Randomized controlled trial of botulinum toxin A for chronic myogenous orofacial pain

&NA; The purpose of this study was to determine whether botulinum toxin A (BTX‐A) was efficacious for the treatment of chronic moderate to severe jaw muscle pain in females. This was a randomized double‐blind, placebo‐controlled crossover trial of BTX‐A. Twenty five units injected into each temporalis muscle and 50 U injected into each masseter muscle using three sites per muscle with 0.2 cm3 per site. Data were collected at baseline, 8, 16, 24 weeks, with crossover occurring at 16 weeks. Primary outcome variables were pain intensity and unpleasantness, measured by horizontal visual analog scale (VAS). Secondary outcome variables were maximum interincisal opening without and irrespective of pain, muscle palpation tenderness (12 points), and four general questions. Fifteen female patients were enrolled (18–45 years), but only ten completed the trial. Of those who finished, no statistically significant difference was found in pain intensity (P=0.10), unpleasantness (P=0.40), palpation muscle tenderness (P=0.91), or the three general questions (P=0.64, P=0.66, P=0.67). Statistical significance was achieved for maximum opening without pain (P=0.02) and irrespective of pain (P=0.005) with the BTX‐A arm having a relative decreased opening. No statistically significant difference was observed in any outcome measures except maximum opening, which showed BTX‐A patient opening less wide than placebo. The results do not support the use of BTX‐A in the treatment of moderate to severe jaw muscle pain in this patient population.

Intraexaminer and interexaminer reliabilities of landmark identification on digitized lateral cephalograms and formatted 3-dimensional cone-beam computerized tomography images

INTRODUCTION The purposes of this study were to determine and compare the intraexaminer and interexaminer reliabilities of commonly used cephalometric landmarks identified on digitized lateral cephalograms and formatted cone-beam computerized tomography (CBCT) images. METHODS CBCT images from 10 randomly selected adolescent patients were obtained from the orthodontic records of a private practice. Measurement errors, and intraexaminer, and interexaminer reliability correlation coefficients (ICC) were obtained for all landmark coordinates. RESULTS Intraexaminer and interexaminer reliabilities for all coordinates for most landmarks on the digital lateral cephalograms and CBCT images were greater than 0.9 (ICC value). The means of landmark locations differed by approximately 1 mm in most coordinates from the lateral cephalograms and were predominantly higher than 1 mm for all coordinates from the CBCT images. CONCLUSIONS Intraexaminer and interexaminer reliabilities were high for most landmarks. Coordinates with greater measurement errors in the lateral cephalograms (condylion, gonion, porion, mandibular incisor apex, and posterior nasal spine) were in structures without clearly defined borders. In the CBCT images, gonion, condylion, and porion were located on surfaces that were flat or curved, making it difficult to recognize a specific reference point. Other less reliable landmarks (anterior nasal spine, posterior nasal spine, mandibular incisor apex) were located in structures with lower densities and could not be visualized with 3-dimensional reconstruction; thus, they had high measurement errors.

The Effect of Vertical and Horizontal Head Positioning in Panoramic Radiography on Mesiodistal Tooth Angulations

The purposes of this study were to examine the effect of potentially common patient positioning errors in panoramic radiography on imaged mesiodistal tooth angulations and to compare these results with the imaged mesiodistal tooth angulations present at an idealized head position. A human skull served as the matrix into which a constructed typodont testing device was fixed according to anteroposterior and vertical cephalometric normals. The skull was then repeatedly imaged and repositioned five times at each of the following five head positions: ideal head position, 5 degrees right, 5 degrees left, 5 degrees up, and 5 degrees down. The images were scanned and digitized with custom software to determine the image mesiodistal tooth angulations. Results revealed that the majority of image angles from the five head positions were statistically significantly different than image angles from the idealized head position. Maxillary teeth were more sensitive to 5 degrees up/down head rotation, with 5 degrees up causing mesial projection and 5 degrees down causing distal projection of maxillary roots. Mandibular anterior teeth were more sensitive to 5 degrees right/left head rotation, with the projected mesiodistal angular difference between 5 degrees right and 5 degrees left rotation ranging from 4.0 degrees to 22.3 degrees. Maxillary teeth were relatively unaffected by 5 degrees right/left head rotation, and mandibular teeth were relatively unaffected by 5 degrees up/down head rotation. It was concluded that the clinical assessment of mesiodistal tooth angulation with panoramic radiography should be approached with extreme caution with an understanding of the inherent image distortions that can be further complicated by the potential for aberrant head positioning.

Analgesic action of gabapentin on chronic pain in the masticatory muscles: A randomized controlled trial

Abstract Chronic masticatory myalgia (CMM) can be defined as constant pain in the masticatory muscles for more than 6 months and is influenced by the central nervous system. The antiepileptic agent gabapentin acts centrally and is used for managing different types of chronic pain conditions. The objective of this study was to evaluate the analgesic action of gabapentin on CMM. In this 12‐week randomized controlled clinical trial 50 patients were randomly allocated into two study groups: 25 received gabapentin and 25 received placebo. The outcome measures utilized were pain reported on a VAS (VAS‐pain), Palpation Index (PI) and impact of CMM on daily functioning reported on a VAS (VAS‐function). Thirty‐six patients completed the study. Gabapentin showed to be clinically and statistically superior to placebo in reducing pain reported by patients (gabapentin = 51.04%; placebo = 24.30%; P = 0.037), masticatory muscle hyperalgesia (gabapentin = 67.03%; placebo = 14.37%; P = 0.001) and impact of CMM on daily functioning (gabapentin = 57.70%; placebo = 16.92%; P = 0.022). It can be concluded from this study that gabapentin is effective for the management of CMM.

Reliability of traditional cephalometric landmarks as seen in three-dimensional analysis in maxillary expansion treatments.

OBJECTIVE To evaluate intra-examiner and inter-examiner reliability of 3D CBCT-generated landmarks previously used in traditional 2D cephalometry. MATERIALS AND METHODS Twenty-four CBCTs NewTom 3G (Aperio Services, Verona, Italy) were randomly selected from patients participating in a clinical trial involving maxillary expansion treatments. The principal investigator located the landmarks five times, and four other investigators located the same landmarks once. Intra-examiner and inter-examiner reliability values were determined using intraclass correlation coefficients (ICCs). To assist in interpretation of the clinical significance of landmark identification differences, average mean differences for x, y, and z landmark coordinates were determined from the repeated assessments. Landmarks then were separated into groups with respect to the region they represented and then were compared via repeated measures ANOVA and multiple comparisons via Bonferroni corrected alpha. RESULTS Intra-examiner and inter-examiner reliability for x, y, and z coordinates for all landmarks were acceptable, all being greater than 0.80. Most of the mean measurement differences obtained from trials within the principal investigator in all three axes were less than 1.5 mm. Inter-examiner mean measurement differences generally were larger than the intra-examiner differences. CONCLUSIONS Based on this, the best landmarks for use in verifying expansion treatment results are Ekm, buccal surface, and apexes of upper molars, upper premolars and upper canines, and buccal surfaces of lower molars and lower canines. Foramen Spinosum, ELSA, Auditory External Meatus, and Dorsum Foramen Magnum demonstrated adequate reliability for determining a standardized reference system.

Effect of buccolingual root angulation on the mesiodistal angulation shown on panoramic radiographs

INTRODUCTION The purpose of this study was to evaluate the effect of buccolingual root angulation on the perception of root parallelism in panoramic images. METHODS A skull-typodont device was constructed according to cephalometric norms. The bases of the typodont were partially sectioned so that the buccolingual orientation of 4 adjacent pairs of teeth could be easily modified. Three buccolingual angulations were used for each tooth. Nine image sequences were necessary to analyze all possible buccolingual orientation combinations between adjacent teeth. The true root parallelism angulations relative to an orthodontic archwire were compared with the angulations obtained from scanned panoramic films. RESULTS The largest root parallelism differences for adjacent teeth occurred between the maxillary canine and the first premolar. The second largest differences occurred in the mandibular canine-premolar area. No significant differences were found in the incisor area. CONCLUSIONS The root parallelism expression in the canine-premolar region can be modified by altering the buccolingual orientation. Buccolingual orientation changes do not seem to affect the incisor area. The clinical usefulness of panoramic radiography to assess root parallelism should be approached with caution, especially in premolar extraction sites.

A comparison of torque expression between stainless steel, titanium molybdenum alloy, and copper nickel titanium wires in metallic self-ligating brackets

OBJECTIVE The force moment providing rotation of the tooth around the x-axis (buccal-lingual) is referred to as torque expression in orthodontic literature. Many factors affect torque expression, including the wire material characteristics. This investigation aims to provide an experimental study into and comparison of the torque expression between wire types. MATERIALS AND METHODS With a worm-gear-driven torquing apparatus, wire was torqued while a bracket mounted on a six-axis load cell was engaged. Three 0.019 x 0.0195 inch wire (stainless steel, titanium molybdenum alloy [TMA], copper nickel titanium [CuNiTi]), and three 0.022 inch slot bracket combinations (Damon 3MX, In-Ovation-R, SPEED) were compared. RESULTS At low twist angles (<12 degrees), the differences in torque expression between wires were not statistically significant. At twist angles over 24 degrees, stainless steel wire yielded 1.5 to 2 times the torque expression of TMA and 2.5 to 3 times that of nickel titanium (NiTi). At high angles of torsion (over 40 degrees) with a stiff wire material, loss of linear torque expression sometimes occurred. CONCLUSIONS Stainless steel has the largest torque expression, followed by TMA and then NiTi.