• Imaging Science in Dentistry
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• v.51 no.2
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• pp.155-165
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• 2021

Purpose: This study aimed to evaluate changes of the alveolar bone and interdental bone septum of the mandibular incisors through cone-beam computed tomography (CBCT) after orthodontic treatment of mandibular dental crowding without dental extraction. Materials and Methods: The sample consisted of 64 CBCT images(32 pre-treatment and 32 post-treatment) from 32 adult patients with class I malocclusion and an average age of 23.0±3.9 years. The width and height of the alveolar bone and interdental septum, the distance between the cementoenamel junction (CEJ) and the facial and lingual bone crests, and the inclination of the mandibular incisors were measured. Results: The distance between the CEJ and the marginal bone crest on the facial side increased significantly (P<0.05). An increased distance between the CEJ and the bone crest on the facial and lingual sides showed a correlation with the irregularity index (P<0.05); however, no significant association was observed with increasing mandibular incisor inclination (P>0.05). The change in the distance between the CEJ and the marginal bone crest on the facial side was correlated significantly with bone septum height(P<0.05). Conclusion: Bone dehiscence developed during the treatment of crowding without extraction only on the incisors' facial side. Increasing proclination of the mandibular incisor was not correlated with bone dehiscence. The degree of dental crowding assessed through the irregularity index was associated with the risk of developing bone dehiscence. The interdental septum reflected facial marginal bone loss in the mandibular incisors.

• Journal of Oral Medicine and Pain
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• v.12 no.1
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• pp.85-93
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• 1987

The author studied on the effect of TMJ sounds to the patterns and ranges of mandibular border movements in horizontal plane with Pantograph (Denar Corp.). For study, 19 patients with TMJ sounds only and 16 students with no TM disorder were selected and classified as experimental group and control group, respectively. The subject performed right lateral movement, left lateral movement, and forward movement. Each movement were performed 3 times and the movement trajectory obtained with mechanical pantograph were observed for accordance of centric relation position, reproducibility and/or restriction of lateral movement paths, deviation of protrusive path in anterior table, restriction of protrusive condylar movement path in posterior horizontal table, presence of Fisher angle in posterior vertical table. And pantographic reproducibility Index (PRI) were obtained with pantronic by the same movement method as in the mechanical pantograph record. The obtained results were as follows : 1. In experimental group, PRI scores in those who show accordance of centric relation position were 14.4, and were 26.53 in those who did not show accordance of centric relation position. However, the PRI scores of the two subgroups show no statistically significant difference in control group. Therefore, in experimental group, the capability of accordance of centric relation position affected largely the PRI scores than in control group. 2. Deviation of protrusive path was opposite to the affected side in experimental group, and was left side in control group. 3. Restriction side of condylar movement in protrusion was ipsilateral to the deviation side in experimental group, but in control group, restriction side was not related to the deviation side. 4. PRI scores in experimental group were 23.2 (moderate dysfunction category), and in control group, were 17.8 (slight dysfunction category). The PRI scores in control group, however, implies that the evaluation of temporomandibular disorders by the PRI scores only may be unreasonable.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.36 no.5
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• pp.185-191
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• 2014

Purpose: Although there have been several studies of reduced airway space after mandibular setback surgery using the sagittal split ramus osteotomy technique, research on the risk factors for changes of the airway space is lacking. Therefore, this study was performed to examine airway changes and the position of the hyoid bone after orthognathic surgery, and to assess possible risk factors. Methods: In this retrospective study, 50 patients who underwent posterior displacement of the mandible by the bilateral sagittal split ramus osteotomy technique were included. Changes of the position of the hyoid bone and the airway space were analyzed over various follow-up periods, using cephalometric radiography taken preoperatively, immediately after surgery, eight weeks after surgery, six months after surgery, and one year after surgery. To identify risk factors, multiple regression analysis of age, gender, body mass index (BMI), posterior mandibular movement, and the presence of genioplasty was performed. Results: Inferor and posterior movement of the hyoid bone was observed postoperatively, but subsequent observations showed regression towards the anterosuperior aspect. The airway space also significantly decreased after surgery (P<0.05), and increased slightly up until six months after surgery. The airway space significantly decreased (${\beta}=0.47$, P<0.01) as the amount of mandibular setback increased. However, age, sex, BMI, and presence of genioplasty were not associated with airway reduction. Conclusion: The amount of mandibular set back was significantly associated with postoperative reduction of airway space. It is necessary to establish a treatment plan considering this factor.

• Journal of Oral Medicine and Pain
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• v.24 no.1
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• pp.37-47
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• 1999

This study was performed to investigate the factors related to vibration of temporomandibular joint during mandibular opening movement. For this study, 144 patients with temporomandibular disorders were randomly selected. Angle's classification, lateral guidance pattern, range of maximal mouth opening, preferred chewing side, and affected side were investigated clinically. Mandibular torque rotational movement during opening was recorded with $BioEGN^{(R)}$ and vibration of temporomandibular joint during opening was recorded with $Sonopak^{(R)}$. After clinical diagnosis was made, visual analogue scale(VAS) was used for evaluation of clinical progress of the subject's chief complaints. The author calculated VAS treatment index(VAS Ti) from the record of VAS. The more VAS Ti was, the less remission of subjective symptom was, The data were analyzed with SAS/Stat program and the results of this study were as follows: 1. There were no significant difference in all the variables of joint vibration by age and sex. 2. Integral and peak amplitude in patients of Angle's class I were higher than those of class II or III patients. Integral in patients of group function was higher than that in patients of canine guidance or other types of lateral excursion. 3. As to Angle's classification or lateral guidance type, there were almost not significant difference between subgroup of same class or type and subgroup of different class or type on both sides. And there were also almost not difference between one side and the other side related to preferred chewing side or affected side. 4. Patients with disk displacement with reduction showed higher value of integral and peak amplitude than any other patients. 5. Joint vibration variables significantly correlated with VAS Ti of pain. with clinical range of mouth opening, and with ingredients of mandibular torque rotational movement.

• Journal of Oral Medicine and Pain
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• v.12 no.1
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• pp.75-83
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• 1987

This study was designed to investigate the effects of TMJ incoordination to condylar movements, especially, the ISS. The sounds are one of the symptoms in TMJ incoordinated disorder, and it may cause the changes of mandibular movement trajectory. 19 students with only TMJ sounds and 16 students with no TMJ problems participated in this study. The subject performed Rt. lateral, Lt. lateral and protrusive movements, and repeated 3 times on each movement. Pantronic was used to record the measures of condylar movement paths. The obtained results were as follows : 1. The mean values of RISS and LISS in control group were 0.29mm, 0.36mm respectively, and those in experimental group were 0.49mm, 0.41mm repectively. The mean values of RISS was higher in experimental group than that of RISS in control group. 2. Correlation coefficients between PRI and RISS, LISS were slightly higher in experimental group than those in control group, therefore, PRI was more likely to be affected by ISS in experimental group. 3. In control group PRI was correlated to RISS, LORB, RPRO and LPRO, but in experimental group PRI was not correlated to those items. From the study, the author knew that the condylar movements was stable in control group.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.44 no.5
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• pp.232-236
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• 2018

Objectives: Hormonal changes during menopause alter a woman's susceptibility to some disorders. Information regarding the prevalence of temporomandibular disorder (TMD) in menopausal women is limited in the literature. In this study, the prevalence and severity of TMDs were compared between menopausal and non-menopausal women. Materials and Methods: The study included 140 women (69 premenopausal and 71 postmenopausal) 45 to 55 years of age that were examined in Shiraz Dental School, Shiraz in Iran. The Helkimo clinical dysfunction index (Di) was used to evaluate temporomandibular joint (TMJ) dysfunction. The data were analyzed using chi-square and Fisher's exact tests. Results: Occurrence of TMD was significantly higher in menopausal than non-menopausal women (P<0.001). All the TMD criteria based on Helkimo Di except range of mandibular movement were significantly more common in menopausal women. The range of mandibular movement was not significantly different between menopausal and non-menopausal women (P=0.178). Conclusion: The results from this study show that TMD can be considered more common and severe in menopausal than non-menopausal women. This finding indicates that, similar to other conditions in menopausal women such as arthritis and osteoporosis, TMD should be taken into consideration by dental and medical professionals.

• The Journal of Korean Academy of Prosthodontics
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• v.24 no.1
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• pp.105-116
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• 1986

In order to determine if a relationship exists between the clinical symptoms of TMJ dysfunction and the reproducibility of mandibular movements, twenty one subjects were chosen. The control group consisted of 5 subjects who were determined to be free from signs and symptoms of dysfunction . The sixteen experimental subjects were selected on the basis of their having dysfunctional symptoms. The author obtained two sets of pantographic tracings. Each set consisted of tracings from three both lateral and one protrusive movements. A second set of tracings were recorded immediately on the new recording papers using the same procedure as the first tracing. The tracings were scored by Pantographic reproducibility index (PRI). The obtained results were as follows. 1. Mean PRI scores of groups increased as the degree of dysfunction were increased. 2. For the groups of no or slight dysfunctional symptoms the PRI scores of the second tracing were smaller than the first one, wherea the scores of the second tracing from $D_2,\;D_3$ group were larger than the first tracing. 3. Differences between the mean PRI scores of control group and those of experimental group were statistically significant. 4. The second sets of tracings were more reliable statistically than those of first ones. 5. PRI can be used as a meaningful aid for the evaluation of the diagnostic and therapeutic results of treatment modalities for the TMJ dysfunction. 6. At 3east two sets of tracings should be recorded when the PRI is to be used to detect the incoordinated movements of TMJ dysfunction patient. 7. PRI scores of control group ($D_0$) was 137.7, thus, mandibular movement was reproducible, whereas PRI scores of experimental groups ($D_1,\;D_2,\;D_3$) were 22.5, 27.7, 30.45 respectively, thus were nonreproducible.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.3
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• pp.288-297
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• 1999

This study has been carried out in order to measure the thickness of soft-tissue on lateral cephalographs based on body mass index(BMI) and the change in soft-tissue thickness after surgical correction of mandibular protrusion. The control material in cephalometric study comprised students at The Dental College, 38 persons, aged 21~24 years and the patient material comprised 20 women and 12men, aged 19~28 years with mandibular protrusion.The thickness of the soft-tissue based on BMI in control and study groups, the comparison between them, immediate postoperative change in the thickness, 6 months after surgery, ratio of soft-tissue response and correlation was established through various statistical methods. The result were as follows : 1. The groups based on BMI showed significant differences each other as regards the linear measurements. The thickest soft-tissue was measured 13.6mm, 15.47mm, 16.76mm at Ss, the thinnest at G' 6.0mm, 6.7mm, 7.26mm respectively. 2. The differences between control and experimental groups based on BMI showed to be significant. There were no differences at G'. The soft-tissue in prognathic patients was thicker at Ss, Ls and thinner at Li, Ls, Pg', Gn', Me'. Differential gap was greater in overweight groups. 3. The immediate soft-tissue change after surgery showed the increase at Li, Ls, Pg', Gn', Me' except G', Ls in all groups. 4. The postoperative soft-tissue change 6 months after surgery was similar with immediate change. The soft-tissue shows the increase in the thickness at Li, Pg', Gn', Me' and the greatest difference occurred at Li, 1.1mm, 0.98mm, 1.2mm respectively. 5. The patients with lower BMI index showed higher soft-tissue response to bony movement at Pg'. The immediate response ratio was 91%, 87%, 81% in A,B,C groups respectively, the response 6 months after surgery showed 96%, 91%, 84%.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.607-617
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• 2002

The purposes of this study were to evaluate the timing of tooth calcification and the change of tooth position with tooth developmental stage on the mandibular teeth. Seven hundred seventy two children(male:446, female:326), 3 to 12 years of age were examined radiographically with panoramic film. Dental development was determined by inspecting radiographs and assigning a rating according to consecutive stages defined by Moorrees, and tooth cusp position and root terminus position were measured from the lower border of mandibular body and calculated the position index to evaluate the movement of tooth with developmental stage. The results were as follows. 1. There were no significant differences between boys and girls in the timing of calcification until crown completion, but timing of calcification tend to be faster in girls than in boys after root initiation stage. 2. In terms of mean age, crown completion of central incisor in boys and girls occurred at the age of 3.71, 4.05 years, at 4.44, 4.60 years for the lateral incisor, at 5.35, 5.11 years for the canine, at 6.62, 6.36 years for the first premolar, at 7.36, 7.17 years of second premolar, at 3.51, 3.69 years of first molar, and at 7.90, 7.64 years for the second molar respectively. Apex 1/2 closed stage of central incisor occurred at the age of 8.70 in boys, 8.18 in girls, at 9.55, 8.99 years for the lateral incisor, at 12.48, 11.60 years for the canine, at 12.30, 12.01 years for the first premolar, at 12.19, 12.26 years of second premolar, at 9.12, 8.87 years of first molar, and at 12.59, 12.45 years for the second molar respectively. 3. There was no noticeable movement of cusp tip until crown completion (Crc), but showed rapid movement toward occlusion plane after root initiation(Ri) and again maintain stable position after root completion stage(Rc). 4. Root terminus position was stable until root 1/4 formation stage(R1/4), followed by rapid movement toward occlusal plane and was stable again after root 3/4 formation stage(R3/4). 5. Developmental stage at the time of alveolar bone penetration by cusp tip varied with each of the permanent teeth. 6. Canine tooth follicle was at the lowest position in the mandibular body during the early stage of calcification, followed by second premolar, first premolar, lateral incisor, second molar, first molar and central incisor in order.

• The Journal of Korean Academy of Prosthodontics
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• v.20 no.1
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• pp.51-66
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• 1982

The purpose of this study was primarily to determine the relationship between temporomandibular joint mobility and generalized benign joint hypermobility. The subjects were 85 men and 76 women, who were students of dental and dental hygiene schools, aged 18 to 30 years old. They had no disturbances or complaints of movement of temporomandibular joints and other joints in the body. The joint mobility was measured by a test which is a modification of a method developed originally by Carter and Wilkinson (1964). The mandibular mobility was measured during active and passive maximal opening, laterotrusion, protrusion, and retrusion by Ingervall's method (1970). The obtained results were as follows: 1. The distribution of joint hypermobility disclosed was 4.8% in men and 19.7% in women, and 11.8% of total subjects. 2. The joint mobility index was a mean of 0.37 for men and 0.51 for women in total subjects, and 0.80 for men and 0.73 for women in hypermobile subjects. 3. The angle of passive dorsiflexion of the little finger was greater in the left than in the right hand for both sexes and in hypermobile subjects than in total subjects. 4. There was a positive correlation between the joint mobility index and the angle of passive dorsiflexion of the little finger in total subjects. 5. The joint mobility was greater in women than in men, and in the left than in the right hand. 6. In the active maximal mandibular movements of total subjects, the mean values for the opening capacity was 56.01 mm and 52.04mm, the laterotrusion mean 8.07 and 8.08, the protrusion mean 8.72 and 8.24, and the retrusion mean 0.48 and 0.49 for men and women respectively. 7. In the passive maximal mandibular movements of total subjects, the mean values for the opening capacity was 59.07mm and 54.85mm, the laterotrusion mean 8.90 and 9.12, the protrusion mean 10.03 and 10.00, and the retrusion mean 0.69 and 0.72 in men and women respectively. The active and passive maximal opening capacity was larger in men than in women but in the other movements there were no significant differences between men and women. 8. The range of active and passive maximal mandibular movements of hypermobile subjects tended to be larger in men but no significant difference in women compared with that of total subjects. 9. The range of maximal mandibular movements was increased more in passive than in active.