Biomedical subjects

Giseon Heo

Publications and source records attributed to Giseon Heo.

At least 19 recordsLinked to original sources

PubMed2006

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

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.

Adolescent↗

PubMed2006

Validity, reliability, and reproducibility of plaster vs digital study models: comparison of peer assessment rating and Bolton analysis and their constituent measurements.

INTRODUCTION: The objective of this validation study was to compare standard plaster models (the current gold standard for cast measurements) with their digital counterparts made with emodel software (version 6.0, GeoDigm, Chanhassen, Minn) for the analysis of tooth sizes and occlusal relationships--specifically the Bolton analysis and the peer assessment rating (PAR) index and their components. METHODS: Dental casts were poured from 24 subjects with 8 malocclusion types grouped according to American Board of Orthodontics categories. Measurements were made with a digital caliper to the nearest 0.01 mm from plaster models and with the software from the digital models. A paired samples t test was used to compare reliability and validity of measurements between plaster and digital methods. RESULTS: Reproducibility of digital models via the concordance correlation coefficient was excellent in most cases and good in some. Although statistically significant differences in some measurements were found for the reliability and validity of the digital models via the average mean of the absolute differences of repeated measurements, none was clinically significant. Grouping of the measurements according to the 8 American Board of Orthodontics categories produced no significant difference (Kruskal-Wallis test). No measurement associated with Bolton analysis or PAR index made on plaster vs digital models showed a clinically significant difference. The PAR analysis and its constituent measurements were not significantly different clinically between plaster and emodel media. CONCLUSIONS: Preliminary results did not indicate that digital models would cause an orthodontist to make a different diagnosis of malocclusion compared with plaster models; digital models are not a compromised choice for treatment planning or diagnosis.

Computer Simulation↗

PubMed2006

Longitudinal study of temporomandibular joint disc status and craniofacial growth.

INTRODUCTION: The objective of this retrospective cohort study was to assess the association of temporomandibular joint (TMJ) disc status and craniofacial growth. METHODS: Seventy-nine subjects (52 female, 27 male) with and without TMJ disc abnormalities were followed for a mean time of 3 years 8 months. Of this sample, 40 subjects (21 female, 19 male) received orthodontic treatment. Disc displacement and disc length measurements from magnetic resonance imaging of the jaw joints were used to evaluate TMJ disc status. A principal component analysis was used to produce a single disc status score per subject. Horizontal and vertical growth changes were obtained from cephalometric radiographs. The Fishman skeletal maturation index system was used to obtain the percentage of the total craniofacial growth attained. In addition, previous orthodontic treatment and time frames between the follow-up cephalometric radiographs were considered. RESULTS: A stepwise multiple linear regression analysis was used to evaluate the influence of TMJ disc status and orthodontic treatment on the displacement vectors between initial records (T1) and final records (T2) for each cephalometric point. Less horizontal and vertical growth was found in specific regions of the maxilla and the mandible in subjects with TMJ disc abnormalities, although their respective determination coefficients were mild (R2 <11.2%). CONCLUSIONS: TMJ disc abnormality was associated with reduced forward growth of the maxillary and mandibular bodies. TMJ disc abnormality was associated with reduced downward growth of the mandibular ramus.

Cephalometry↗

PubMed2006

Variations in orthodontic treatment planning decisions of Class II patients between virtual 3-dimensional models and traditional plaster study models.

INTRODUCTION: Study models provide invaluable information in treatment planning. Digital models have proved to be an effective measurement tool, but their use in treatment planning has not been studied. METHODS: Ten sets of records of Class II malocclusion subjects (dental study models, lateral cephalograms/tracings, panoramic radiographs, intraoral and extraoral photographs) were used for treatment planning by 20 orthodontists on 2 separate occasions. Digital models were used to evaluate the patients at 1 session and plaster models were used at the other session. Treatment recommendations were scored and compared for agreement. Eleven orthodontists served as the control group, looking at the records on 2 occasions with plaster models for agreement. RESULTS: Good agreement was noted for surgery (P = 1.00, kappa = 0.549), extractions (P = .360, kappa = 0.570), and auxiliary appliances (P = 1.00, kappa = 0.539) for the digital/plaster group. Agreement in the plaster/plaster group for surgery (P = 1.00, kappa = 0.671), extractions (P = 1.00, kappa = 0.626), and auxiliary appliances (P = .791, kappa = 0.672) was also good. Overall proportions of agreement ranged between 0.777 and 0.870 for digital/plaster and 0.818 and 0.873 for plaster/plaster. CONCLUSIONS: There was no statistical difference in intrarater treatment-planning agreement for Class II malocclusions based on the use of digital models in place of traditional plaster models. Digital orthodontic study models (e-models) are a valid alternative to traditional plaster study models in treatment planning for Class II malocclusion patients.

Computer Simulation↗

PubMed2006

Predictive factors of vertical bone depth in the paramedian palate of adolescents.

OBJECTIVE: To determine whether a relationship exists between the vertical bone depth in the paramedian palate (PP) of growing patients and age, gender, and palatal morphology. Clinically detectable traits may decrease the need for further imaging prior to implant placement for orthodontic anchorage. MATERIALS AND METHODS: Cone beam computed tomagraphic scans (Newtom-9000, Verona, Italy) were acquired in 183 orthodontic patients (10-19 years old). Vertical bone depth was measured at nine unilateral locations in the PP of each subject. Measurements were analyzed with univariate and multivariate statistical tests. RESULTS: Significant variability in the bone thickness was found among locations and among subjects. Male subjects had significantly greater mean bone thickness in six of the nine locations measured, showing a mean of 1.22 mm more vertical bone than females showed at these locations. Age and palatal measurements did not demonstrate a clinically useful relationship with bone depth. CONCLUSIONS: Age and palatal morphology are not valid predictors of bone height in the PP. Because of the large variability of bone thickness in this region, computed tomographic imaging remains valuable prior to paramedian implant placement in growing individuals. The paramedian palate presents a promising region for palatal implant placements when the midpalatal suture is to be avoided.

Adolescent↗

PubMed2006

Meta-analysis of immediate changes with rapid maxillary expansion treatment.

BACKGROUND: The authors conducted a literature review to evaluate immediate transverse, anteroposterior, and vertical dental and skeletal changes produced by rapid maxillary expansion (RME). TYPES OF STUDIES REVIEWED: The authors reviewed clinical trials that assessed immediate dental and/or skeletal changes after RME using cephalometric analysis, model casts or both. No surgical or other simultaneous treatment was accepted during the evaluation period. RESULTS: The authors searched electronic databases and found 31 articles that met the initial inclusion criteria. The authors later rejected 12 of these articles because they did not report immediate changes, three because they lacked detailed descriptions of their results and two because of their nonconventional appliance designs. Fourteen articles satisfied th final inclusion criteria; however, they had methodological deficiencies. CLINICAL IMPLICATIONS: The greatest changes resulting from RME in the studies analyzed were dental and skeletal transverse changes. Few vertical and anteroposterior immediate changes were statistically significant, though they probably are not clinically important.

Cephalometry↗

PubMed2006

Masticatory muscle reaction in simulated low-velocity rear-end impacts.

AIMS: To evaluate the electromyographic (EMG) activity of masseter and temporalis muscles in relation to impact awareness, gender, impact magnitude, and kinematics of head movement in simulated low-velocity rear-end impacts. METHODS: Twenty-nine individuals (17 men and 12 women) were subjected in random order to 3 rear-end impacts: 2 unexpected impacts (chair accelerations of 4.5 m/s2 and 10.1 m/s2) and 1 expected impact (chair acceleration of 10.1 m/s2). The EMG activity of the deep and superficial masseter muscle was recorded bilaterally. EMG activity was also recorded for the left anterior temporalis muscle. Angular acceleration and angular displacement of the head were also recorded. The temporal relationship between onset of the masticatory muscle activity and maximum peak of the kinematics of head movement was determined. RESULTS: The magnitude of normalized masticatory EMG activity ranged from 1.4 to 1.8 times higher (P < .05) for fast unexpected impacts compared to slow unexpected impacts in all masticatory muscles. The magnitude of normalized anterior temporalis EMG peak response ranged from 1.8 to 2.5 times higher (P < .05) in female subjects than in male subjects for all impacts. No significant differences were identified for impact awareness in the magnitude of normalized EMG activity for any masticatory muscle. No significant differences were identified with respect to timing of masticatory muscle response (P > .05). CONCLUSION: EMG activity increased with increased impact magnitude. Temporal and amplitude awareness of a simulated impact did not produce a difference in the masticatory muscle response. Gender differences were identified in the anterior temporalis muscle response. The onset of the masticatory muscle response occurred after peak angular acceleration of the head but prior to peak angular displacement of the head.

Accidents, Traffic↗

PubMed2005

Kinematics of head movement in simulated low velocity rear-end impacts.

OBJECTIVES: To evaluate kinematics of head movement related to impact velocity, gender and awareness in simulated low velocity rear-end impacts. METHODS: Thirty individuals were subjected in random order to three rear-end impacts: two unexpected impacts causing chair acceleration of 4.5m/s2 (slow) and 10.0m/s2 (fast) and one 10.0m/s2 expected impact. Rearward head displacement, and linear and angular head accelerations were recorded. RESULTS: Angular head displacement was almost two times higher for the fast than the slow unexpected-impacts (P=0.04). Rearward and forward angular head accelerations increased two to three times with increased impact magnitude (P<0.05). Rearward and forward linear head accelerations were two and a half to three and a half times higher for the fast than for the slow unexpected impacts (P<0.05). Males presented two times higher upward linear head acceleration than females in the unexpected fast impact. No significant magnitude differences were identified for impact awareness in kinematics of head movement (P>0.05). Rearward angular head acceleration reached the peak between 62 and 84 ms later than the rearward linear head acceleration (P<0.05) in all impacts. No significant differences were identified for timing of kinematics of head movement (P>0.05) with increased impact magnitude; however, statistical powers were low. INTERPRETATION: Kinematics of head movement increases with increased impact magnitude. Gender differences exist for vertical linear head acceleration only. Temporal and amplitude awareness do not change the magnitude in kinematics of head movement. There are temporal differences between angular and linear head accelerations.

Acceleration↗

PubMed2005

The role of sternocleidomastoid muscle in simulated low velocity rear-end impacts.

The objectives of this study were to evaluate behavior of sternocleidomastoid muscle (SCM) electromyogram (EMG) related to impact velocity, gender, awareness and kinematics of head movement in simulated low velocity rear-end impacts. Twenty-nine healthy adults (17 male) were subjected in random order to three rear-end impacts: Two unexpected impacts causing chair accelerations of 4.5 m/s(2) (slow) and 10.1 m/s(2) (fast) and one 10.1 m/s(2) expected impact. Normalized left and right SCM EMG, linear head acceleration, angular head acceleration and maximum angular head displacement were recorded. The magnitude of normalized SCM EMG peak response ranged 2-3 times higher (P< 0.001) in female subjects than their counterpart male subjects. SCM EMG magnitude was 3-4 times higher (P< 0.001) for the fast unexpected than slow unexpected impacts, but there was no significant difference (P> 0.05) for the fast expected compared to the fast unexpected impacts. The onset time of SCM peak EMG ranged from 78 ms to 114 ms later than peak of linear head acceleration for all groups. Onset time of peak SCM EMG was not significantly different (P> 0.05) than onset of angular acceleration for the slow and fast-unexpected impacts, but onset peak SCM EMG was significantly earlier than peak angular head acceleration (30 ms) (P </= 0.05) for the fast expected impact. SCM EMG magnitude increased with increased impact velocity. Gender differences exist for SCM EMG magnitude. Temporal and amplitude awareness of a simulated impact do not produce different magnitude of SCM EMG response. The temporal relationship between the SCM and angular head acceleration is different from the temporal relationship between the SCM and linear head acceleration.

Acceleration↗

PubMed2005

Predictors for Class II treatment duration.

BACKGROUND: The purpose of this study was to identify clinical factors that predict treatment length for patients with Class II malocclusions. METHODS: A sample of 237 active retention patients representing 3 observational groups (Angle Class I nonextraction, and Class II Division 1 extraction and nonextraction), based on specific selection criteria, was obtained from 3 private offices. From the patient records, data were collected in these categories: (1) patient information, (2) model information, (3) pretreatment cephalogram information, and (4) treatment information. Two regression analyses were completed, with total treatment time as the dependent variable for both models. RESULTS: The first regression analysis (Class I and Class II patients) indicated significant predictors for the patient, model, and cephalometric variables. These predictors included age, pretreatment overjet, and pretreatment ANB angle. The second regression analysis (Class II treatment variables) identified the following factors as significantly associated with treatment length: (1) type of Class II appliance, (2) number of months of Class II appliance wear, (3) number of months of interarch elastic wear, (4) maxillary expansion, (5) number of debonds, and (6) average time (weeks) between appointments. CONCLUSIONS: Six variables explained 56.7% of the variation in Class II treatment length. Further research is required to help explain more of the variance associated with treatment duration.

Adolescent↗

PubMed2005

True incisor intrusion attained during orthodontic treatment: a systematic review and meta-analysis.

INTRODUCTION: The purpose of this meta-analysis was to quantify the amount of true incisor intrusion attained during orthodontic treatment. METHODS: Electronic databases (PubMed, Medline, Medline In-Process & Other Non-Indexed Citations, all EBM reviews [Cochrane Database of Systematic Reviews, ASP Journal Club, DARE, and CCTR], Embase, Web of Science, and Lilacs) were searched with the help of a senior health sciences librarian. The goal was to identify clinical trials that assessed true incisor intrusion through cephalometric analysis and factored out craniofacial growth when required. From the selected abstracts, original articles were retrieved, and their references were hand searched for missing articles. RESULTS: Twenty-eight articles met the initial inclusion criteria, but 24 were rejected because they did not quantify true incisor intrusion or factor out normal growth impact when required. The remaining 4 articles showed that true incisor intrusion is attainable (0.26 to 1.88 mm for the maxillary incisors and -0.19 to 2.84 mm for the mandibular incisors) but with large variability depending on the appliance used. A meta-analysis with results from the 2 articles that used the segmental technique was completed. The combined mean estimates of intrusion and 95% CI were 1.46 mm (1.05-1.86 mm) for the maxillary incisors and 1.90 mm (1.22-2.57 mm) for the mandibular incisors. CONCLUSIONS: True incisor intrusion is achievable in both arches, but the clinical significance of the magnitude of true intrusion as the sole treatment option is questionable for patients with severe deepbite. In nongrowing patients, the segmented arch technique can produce 1.5 mm of incisor intrusion in the maxillary arch and 1.9 mm in the mandibular arch.

Cephalometry↗

PubMed2005

Condylar shape analysis using panoramic radiography units and conventional tomography.

OBJECTIVE: The objective of this study was to compare condyle shape between lateral temporomandibular joint (TMJ) images from axially corrected tomography and 3 panoramic radiography units with TMJ-specific programs. STUDY DESIGN: The TMJ from a single dry human skull was imaged with multidirectional tomography and the following 3 panoramic radiography units: Instrumentarium OP 100, Planmeca PM 2002 CC Proline, and Soredex Orthophos DS. A curve-fitting procedure (spline curves) was used to mathematically describe condyle outlines. One sample t tests were used to compare panoramic images against the tomograms (gold standard). RESULTS: A significant difference (P < .05) in condyle shape was found between TMJ tomography images and each of the 3 panoramic images. Images from the PM 2002 CC Proline demonstrated the smallest shape difference (13.4%), followed by the OP 100 (17.5%) and the Orthophos DS (24.8%). CONCLUSION: If panoramic radiography is to be used for the initial radiographic examination of the TMJ, practitioners should be aware of the potential for shape distortion of the condyle.

Analysis of Variance↗

PubMed2004

An evaluation and comparison of orthodontic bracket bond strengths achieved with self-etching primer.

The bonding of orthodontic brackets to enamel is a multistep process. To simplify bonding and decrease chair time, Transbond Plus Self-Etching Primer (3M Unitek, Monrovia, Calif) has been introduced; the primer combines the etching, rinsing, and priming steps. This in vitro study evaluated the shear bond strengths and interoperator variability of self-etching primer, as compared with conventional phosphoric acid etching with 2 common orthodontic resins. A total of 214 teeth were bonded, according to the following protocols: group A: self-etching primer plus Transbond XT light-cured resin (3M Unitek); group B: 35% phosphoric acid (15 seconds) plus Transbond XT resin; and group C: 37% phosphoric acid (15 seconds) plus Enlight bonding resin (Ormco, Glendora, Calif). Significantly higher bond strengths were seen in group B than in group A (P =.004) and group C (P =.002). The mean shear bond strengths of group A were not significantly different from those of group C (P =.99). When 3 orthodontists bonded a total of 60 premolars using the protocols of groups A and B, significant differences in shear bond strengths and strength ranking were found. The mean values they obtained using the self-etching primer were not significantly different, but significant differences in mean values were found between operators when the phosphoric acid-etching technique was used.

Acid Etching, Dental↗

PubMed2004

The relationship between occupational stress and job satisfaction in orthodontics.

The goal of this project was to describe the relationship between overall occupational stress (OS), categories of stressors, overall job satisfaction (JS), and facets of JS in orthodontics. Canadian orthodontists were mailed an anonymous, self-administered survey. The response rate was 51.2% (335 of 654). The survey included a list of 67 potential stressors representing 6 categories, an overall OS score, and a modified version of the Dentists Satisfaction Survey (DSS). The correlation between the overall OS score and the overall JS scale of the DSS was r = -0.392. The overall OS scores were most strongly correlated to satisfaction with personal time (r = -0.385, P <.01) and satisfaction with practice management (r = -0.334, P <.01). Work-related stressors (r = -0.301, P <.01) and income-related stressors (r = -0.268, P <.01) were the categories with the highest correlation to the overall JS scale. Orthodontists reporting low OS had significantly higher satisfaction scores on all sections of the DSS. This difference was greatest in satisfaction with personal time and practice management. The results indicate the importance of OS in determining JS in orthodontics.

Adult↗

PubMed2003

Job satisfaction among Canadian orthodontists.

Job satisfaction has been well researched for many professions, including general dentistry. The job satisfaction of orthodontists has not been adequately studied. The aims of this study were to describe job satisfaction among orthodontists and to determine characteristics associated with job satisfaction in the profession. A self-administered, anonymous survey was mailed to Canadian orthodontists. It included a modified version of the Dentist Satisfaction Survey, an overall occupational stress score, and items addressing various characteristics of the respondents. Of 654 mailed surveys, 335 were returned, for a response rate of 51.2%. Most orthodontists (79.3%) were classified as satisfied according to the overall job satisfaction scale of the Dentist Satisfaction Survey; however, some (2.5%) were classified as dissatisfied. The facets of orthodontics with the highest degree of satisfaction were patient relations (93%), delivery of care (86%), respect (84%), professional relations (80%), and staff (76%). The most dissatisfaction was associated with personal time (26%) and practice management (15%). Stepwise multiple regression analysis resulted in a model including overall occupational stress, membership in the Canadian Association of Orthodontists, total number of staff, and age to account for 27.1% of the variation in the overall job satisfaction scale. Based on accountable sources of variance, the overall job satisfaction scale seems to be more affected by other variables than the characteristics evaluated by this survey.

Age Factors↗

PubMed2003

Occupational stress among Canadian orthodontists.

The occupational stress associated with many professions, including general dentistry, has been well researched. An anonymous, self-administered, mail-out survey was distributed to Canadian orthodontists. The survey included 67 potential stressors, an overall occupational stress score, an overall job satisfaction scale, and items addressing various characteristics of the respondents. The response rate was 51.2% (335/654). Pronounced differences were found between the respondents in the evaluation of potential stressors and the overall occupational stress score. The category of stressors with the highest mean severity of stress scores was time-related stressors. The stressors with high mean severity scores and high mean frequency scores were as follows: falling behind schedule, trying to keep to a schedule, constant time pressures, patients with broken appliances, and motivating patients with poor OH and/or decalcification. Stepwise multiple regression determined a model, involving overall job satisfaction, age, participation in a study group, hours worked per week, part-time academics, days of continuing education per year, and participation in stress management, to account for 35.9% of the variation in overall occupational stress scores. The results indicate the importance of time-management skills in reducing occupational stress, but other factors seem to have more effect on reported occupational stress than do the characteristics addressed by this survey.

Age Factors↗

PubMed2003

A comparison of dynamic and static testing of latex and nonlatex orthodontic elastics.

The purpose of this study was to determine the effects of repeated stretching (cyclic testing) and static testing on the force decay properties of two different types of orthodontic elastics from a single supplier. Samples of American Orthodontics' 0.25 inch, 4.5 oz (6.35 mm, 127.5 g) latex and nonlatex elastics were used and a sample size of 12 elastics per group was tested. Static testing involved stretching the elastics to three times marketed internal diameter (19.05 mm) and measuring force levels at intervals over 24 hours. Cyclic testing used the same initial extension but cycled the elastics an additional 24.7 mm to simulate extension with maximal opening in the mouth. Both types of elastic had similar initial forces that were statistically below the marketed force (122 and 118 g for latex and nonlatex elastics, respectively) at three times marketed internal diameter. Cyclic testing caused significantly more force loss and this difference occurred primarily within the first 30 minutes. For statically tested elastics the percentage of initial force remaining at 4, 8, and 24 hours was 87%, 85%, 83%, and 83%, 78%, 69% for latex and nonlatex elastics, respectively. For cyclically tested elastics the percentage of initial force remaining at 4, 8, and 24 hours was 77%, 76%, 75%, and 65%, 63%, 53% for latex and nonlatex elastics, respectively.

Analysis of Variance↗

PubMed2003

An in vitro comparison of 4 brands of nonlatex orthodontic elastics.

The purpose of this study was to compare 4 brands of nonlatex orthodontic elastics with respect to initial force produced and force decay over a 24-hour period. Sample sizes of 12 elastics from American Orthodontics (Sheboygan, Wis), Ortho Organizers (San Marcos, Calif), GAC International (Islandia, NY), and Masel (Bristol, Pa) were used. Equivalent or near-equivalent products were tested: the quarter-in (6.35 mm), 4 or 4.5 oz (113 or 128 g) elastics from each company. An apparatus that repeatedly cycled the elastics to simulate interarch usage with chewing was used to measure force decay over a 24-hour period. Results showed a wide range of initial forces between the brands at an extension of 3 times the marketed internal diameter. The elastics from American Orthodontics, Ortho Organizers, and Masel generated forces statistically below their marketed force levels at 3 times their marketed internal diameter extensions. GAC elastics generated significantly higher forces than marketed at 3 times internal diameter extension. All elastics generated forces below those marketed at 2 times internal diameter. Initial force production was significantly correlated with the measured cross-sectional area of the elastics (P <.01). The force decay patterns of all brands were very similar, but there were significant differences in their abilities to withstand testing. Grouped average percentages of initial force at 4, 8, and 24 hours were 68%, 61%, and 49%, respectively, for the elastics that did not break during testing.

Analysis of Variance↗