• Journal of Korean Dental Science
• /
• v.7 no.2
• /
• pp.66-79
• /
• 2014

Purpose: To analyze the amount and pattern of tooth movement and the changes in arch dimension of mandibular dentition after orthodontic treatment using a new three-dimensional (3D)-indirect superimposition method. Materials and Methods: The samples consisted of fifteen adult patients with class I bialveolar protrusion and minimal anterior crowding, treated by extraction of four first premolars with conventional sliding mechanics. After superimposition of 3D-virtual maxillary models before and after treatment using best-fit method, 3D-virtual mandibular model at each stage was placed into a common coordinate of superimposition using 3D-bite information, which resulted in 3D-indirect superimposition for mandibular dentition. The changes in mandibular dental and arch dimensional variables were measured with Rapidform 2006 (INUS Technology). Paired t-test was used for statistical analysis. Result: The anterior teeth moved backward, displaced laterally, and inclined lingually. The posterior teeth showed statistically significant contraction toward midsagittal plane. The amounts of backward movement of anterior teeth and forward movement of posterior teeth showed a ratio of 6 : 1. Although the inter-canine width increased slightly (0.8 mm, P<0.05), the inter-second premolar, inter-first molar, and inter-second molar widths decreased significantly with similar amounts (2.2 mm, P<0.05; 2.3 mm, P<0.01; 2.3 mm, P<0.001). The molar depth decreased (6.7 mm, P<0.001) but canine depth did not change. Conclusion: A new 3D-indirect superimposition of the mandibular dentitions using best-fit method and 3D-bite information can present a guideline for virtual treatment planning in terms of tooth position and arch dimension.

• The Journal of Korean Academy of Prosthodontics
• /
• v.29 no.1
• /
• pp.39-52
• /
• 1991

The purpose of this study were to compare the condylar path and the anterior angle of glenoid fossae, and analyze the condylar path, and classify the patterns of condylar path. Thirty-three male and female dental students with normal occlusion and masticatory system ranging in age from 24 to 27, without present symptoms and any history of TM joint disturbance, were selected for this study. Then, sixty-six TM joint were examed. Transcranial radiographs of TM joint and Cephalometric radiographs under mandibular protrusive movement were obtained. They were taken at six positions on protrusive movement. The results obtained were as follows : 1. The sequence of the frequeny of condylar movement patterns were concave curve, "S"shape curve, convex curve, and reverse "S"shape. 2. The horizontal distance of the greatest changed position of condylar angle averaged 2.6mm. 3. The condylar path angle averaged 36.91 degree. 4. The angle of the anterior slope of glenoid fossae averaged 37.28 degree. 5. The distance fo condylar movement averaged 5.98mm and the distance of condylar horizontal movement averaged 4.71mm. 6. The slope of articular eminence was correlated to the condyalr path and three were no significant differences between right and left side of the anterior slope of articular eminence, and the condyalr path angle.

• The korean journal of orthodontics
• /
• v.45 no.6
• /
• pp.275-281
• /
• 2015

Objective: To assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models. Methods: Cone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by Student's t-test. Results: The mean discrepancies in maxillary and mandibular crown positions were $0.376{\pm}0.041mm$ and $0.398{\pm}0.037mm$, respectively. Maxillary and mandibular root positions differed by $2.062{\pm}0.128mm$ and $1.941{\pm}0.154mm$, respectively. Conclusions: Crowns but not roots of anterior teeth can be moved to designated positions using clear aligners, because these appliances cause tooth movement by tilting motion.

• Journal of Oral Medicine and Pain
• /
• v.13 no.1
• /
• pp.85-93
• /
• 1988

The author studied maximum clenching EMG activities of temporalis anterior and masseter muscle during canine guidance and centric occlusion. It was performed before and after anesthesia of maxillary and mandibular canines. The 22 normal subjects (15 males and 7 females) who had healthy maxillary and mandibular canines were selected. Their occlusal contact scheme was canine guidance during movement and they did not have temporomandibular disorder. The results were as follows : 1. The maximum clenching EMG activities of temporalis anterior and masseter muscle during guidance were less than those during centric occlusion. 2. After left maxillary and mandibular canines were anesthetized with 2% lidocanine with 1:100,000 epinephrine, the maximum clenching EMG acivities of temporalis anterior and masseter muscle during left canine guidance were greater than those before anesthesia of left maxillary and mandibular canines(p<0.01) 3. The maximum clenching EMG activities of temporalis anterior and masseter muscle during right guidance were not significantly different between before and after anesthesia of left maxillary and mandibular canines(p>0.05).

• Journal of Oral Medicine and Pain
• /
• v.17 no.1
• /
• pp.61-71
• /
• 1992

52 Dental students without masticatory problems were selected for this study. They were trained on several mandibular position and mandibular movement exercise, that is, rest position, light bite, tapping, hinge opening, habitual opening, opening limitation, stretch exercise, resistance exercise and clenching. The objectives of this study was to investigate the effects of mandibular movement exercise, especially stretch and resistance, on the experimentally guided limited mouth opening. Muscle activity of the anterior temporalis and the masseter on above mentioned position or exercise were recorded with bioelectric processor EM2(Myotronics, U.S.A.) and the data were processed with SPSS. The obtained results were as follows : 1. Activity of the muscles at rest position were decreased with mandibular movement exercise. 2. Forceful mouth opening on opening limitation increased muscle activity greatly, especially of the masseter. 3. On opening limitation, stretch or resistance exercise was very efficient for decrease of muscle activities. 4. There were no difference of muscle activity between on hinge opening and on habitual opening. Therefore, for muscle relaxation, the two movement exercise can be used interchangeably.

• The korean journal of orthodontics
• /
• v.54 no.3
• /
• pp.171-184
• /
• 2024

Objective: This study aimed to determine the maxillary and mandibular basal bone regions and explore the three-dimensional positional relationship between the dentition and basal bone regions in patients with skeletal Class I and Class II malocclusions with mandibular retrusion. Methods: Eighty patients (40 each with Class I and Class II malocclusion) were enrolled. Maxillary and mandibular basal bone regions were determined using cone-beam computed tomography images. To measure the relationship between the dentition and basal bone region, the root position and root inclination were calculated using the coordinates of specific fixed points by a computer program written in Python. Results: In the Class II group, the mandibular anterior teeth inclined more labially (P < 0.05), with their apices positioned closer to the external boundary. The apex of the maxillary anterior root was positioned closer to the external boundary in both groups. Considering the molar region, the maxillary first molars tended to be more lingually inclined in females (P = 0.037), whereas the mandibular first molars were significantly more labially inclined in the Class II group (P < 0.05). Conclusions: Mandibular anterior teeth in Class II malocclusion exhibit a compensatory labial inclination trend with the crown and apex relative to the basal bone region when mandibular retrusion occurs. Moreover, as the root apices of the maxillary anterior teeth are much closer to the labial side in Class I and Class II malocclusion, the range of movement at the root apex should be limited to avoid extensive labial movement.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.34 no.4
• /
• pp.246-251
• /
• 2012

Purpose: The purpose of the study is to evaluate the effectiveness of anterior segmental osteotomy (ASO) in bimaxillary protrusion (BP) patients by comparison between the mandibular soft and hard tissue changes from orthodontic treatment and ASO. Methods: All 44 patients were diagnosed with BP in Kyung-Hee Medical Center. Orthodontic treatment with teeth extractions were underwent by 23 patients (Group A) and 21 patients underwent ASO (Group B). Mandibular soft and hard tissue changes were measured and evaluated, which were based on the vertical and horizontal reference line in lateral cephalometric radiographs. Statistical significance between the changes and correlation between each measurement were analyzed. Results: The amount of B point movement was lesser than that of the lower incisal tip (LIT) retraction, and LIT was tilted lingually in group A. The posterior movement discrepancy between LIT and B point was insignificant, and the inclination of lower incisor was not changed in group B. The soft tissues, including the lower lip, showed a posterior movement and reduction in the depth of mento-labial groove. According to the correlation analysis, the movement of the lower incisor was significantly related to the movement of the lower lip in group A, and the movement of the lower incisor was significantly related to that of the movement of lower lip, B point and Pog in group B. Conclusion: The orthodontic treatment in BP patients results in posterior tilting movement of the lower incisor, but ASO results in the bodily movement of the lower incisor. Consequently, ASO is more effective in BP cases because it ensures the controlled movement of the lower incisors.

• The korean journal of orthodontics
• /
• v.13 no.2
• /
• pp.131-146
• /
• 1983

Faces of normal occlusion, open bite and class III malocclusion were measured using cephalogram in 190 male and female subjects. Using M.K.G., types of mandibular movement, amount of horizontal and vertical movement were studied in relation to occlusal types, and were compared with each other. The following conclusions were obtained. 1. Movement of protrusion was most different in relation to occlusal type. 2. In normal occlusion, maximal protrusion were horizontal 7.66mm, vertical 3.01mm in male, 6.41, 2.92mm respectively in female and maximal inferior position were -24.32, 33.63mm in male,-23.48, 32.27mm respectively in female. 3. Angle between maximal inferior position and horizontal plane were $53.51^{\circ}$ in male, $53.84^{\circ}$ in female. 4. Generally, amount of mandibular movement was greater in male than female. 5. In open bite, path of protrusion was nearly straight without curve $69.2\%$ in male, $70.2\%$ in female. 6. In class III malocclusion, angle and amount of protrusion were smaller than normal occlusion and path was directed anterior-superiorly in $22.7\%$. 7. There was no correlation coefficient between measurement of face and mandibular movement.

• The korean journal of orthodontics
• /
• v.37 no.3 s.122
• /
• pp.220-230
• /
• 2007

Objective: The purpose of this study was to determine the changes of mandibular anterior alveolar bone thickness with age. Methods: Cephalometric radiographs of 160 skeletal class I patients (male 80, female 80) with normal vertical growth pattern was investigated by measuring the buccolingual thickness of mandibular alveolar bone on the basis of root axis. Results: As the age increases, both male and female showed a significant decrease in buccolingual width of the mandibular anterior alveolar bone and in the width of mandibular anterior lingual alveolar bone except the CEJ area of females. However, there was no significant difference in the thickness of mandibular anterior buccal alveolar bone and in the width of maximum prominence of mandibular symphysis with age. Conclusion: From the above results, it is concluded that Korean children whose growth pattern is sagittally skeletal class l with a vertical normal growth pattern have a greater mandibular anterior lingual alveolar bone width than Korean adults; therefore, lingual movement of mandibular incisors, which is usually accompanied in extraction treatment, is considered to be more preferable in younger patients.

• Journal of Oral Medicine and Pain
• /
• v.13 no.1
• /
• pp.43-52
• /
• 1988

The author studied masticatory muscle activity and bite force in normal persons without Temporomandibular Disorders(TMD) signs and symptoms, The number of subjects was 15, and the age of them was from 22 to 25 years. Electromyography was used to record the muscle activity in tapping and clenching movement with or without occlusal splint. 3 splints were made from 3 different mandibular position, that if, centric occlusion position, Rocabado's mandibular rest position, Dawson's centric relation position. The thickness of splint was 3.0-3.5㎜ at molar region. The muscle examined were Masseter and Anterior Temporalis attached with surface electrodes and the device used to measure the EMG level was Bioelectric processor Model EM2. After recording the EMG, the author measured the bite force level in clenching movement with bite force meter Model MPM-3000 in the dame position used in the EMG experiment. The obtained results were as follow : 1. With occlusal splints insetion, the amount of decreased muscle activity in Anterior Temporalis was more than those in Masseter. 2. In the three maxillomandibular relationships with occlusal splints, Masseter showed slightly increased level of muscle in centric occlusion but Ant. Temporalis showed decreased level of muscle activity reversely in that position. 3. Muscle activities between Rocabado's rest position and Dawson's centric relation position were generally similar whatever the muscles or the movements the author examined. 4. Bite force in clenching movement increased with splints insertion, especially with the splint registered in centric occlusion position.