• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제31권2호
• /
• pp.136-142
• /
• 2009

Bone density in the recipient implant site seems to be an important factor for long term success of endosseous implants. Preoperative evaluation of bone density is very helpful to assist the clinician with the treatment planning of implant therapy. Accurate information on bone density will help the surgeon identify suitable implant sites, thereby improving the success rate of the procedure. Purpose; The aim of this study was to evaluate a correlation between bone density measured preoperatively with computerized tomography and histologically measured bone density by bone biopsy. Patients and methods; Twenty seven patients were selected. All the patients were in good health, with no systemic disorder and additional bone graft. Preoperatively the patients underwent CT scanning to evaluate Houmsfield Unit(HU). Each patients wore a surgical template for implant placement. During surgery 2mm in diameter and 6mm in length specimens were taken. Histomorphometric analysis was performed using digitalized image analysis software Axiovision 4.3. Also, the Resonance frequency analysis(RFA) and insertion torque values were recorded. Results; The highest histomorphometric values was found in the posterior mandible $32.3{\pm}3.8$, followed by $29.9{\pm}2.6$ for the posterior maxilla, $29.4{\pm}2.6$ for the anterior maxilla, $28.6{\pm}2.3$ for the anterior mandible(p=0.214). The hounsfield unit was $989.2{\pm}258.1$ in the posterior mandible, $845.0{\pm}241.5$ in the anterior maxilla, $744.5{\pm}92.6$ in the anterior mandible, $697.3{\pm}136.9$ in the posterior maxilla(p=0.045). This results may suggest that there are strong correlation between the histomorphometric values and hounsfield unit(r=0.760, p<0.05). The RF measurements were $81.9{\pm}2.4$ ISQ in the posterior mandible, $79.0{\pm}1.4$ ISQ in the anterior mandible, $78.3{\pm}4.6$ ISQ in the posterior maxilla, $76.5{\pm}5.0$ ISQ in the anterior maxilla(p=0.048). The insertion torque values was $43.2{\pm}4.2\;Ncm$ in the posterior mandible, $42.0{\pm}0.0\;Ncm$ in the anterior mandible, $41.3{\pm}4.1\;Ncm$ in the posterior maxilla, $40.8{\pm}3.8\;Ncm$ in the anterior maxilla(p=0.612). This results may suggest that there are statistical significance between the hounsfield unit and the insertion torque values(r=0.494, p<0.05), the histomorphometric values and the insertion torque values(r=0.689, p<0.05). But there was no correlation between histomorphometric values and ISQ. There was no statistical significance in age and gender effect on parameters. Conclusions; There was significant correlations between bone density and implant stability parameters. The bone density measurements using preoperative CT may help clinicians to predict primary stability before implant insertion, which is associated with implant survival rates.

• Imaging Science in Dentistry
• /
• 제43권4호
• /
• pp.227-233
• /
• 2013

Purpose: This study was performed to analyze human maxillary and mandibular trabecular bone using the data acquired from micro-computed tomography (micro-CT), and to characterize the site-specific microstructures of trabeculae. Materials and Methods: Sixty-nine cylindrical bone specimens were prepared from the mandible and maxilla. They were divided into 5 groups by region: the anterior maxilla, posterior maxilla, anterior mandible, posterior mandible, and mandibular condyle. After the specimens were scanned using a micro-CT system, three-dimensional microstructural parameters such as the percent bone volume, bone specific surface, trabecular thickness, trabecular separation, trabecular number, structure model index, and degrees of anisotropy were analyzed. Results: Among the regions other than the condylar area, the anterior mandibular region showed the highest trabecular thickness and the lowest value for the bone specific surface. On the other hand, the posterior maxilla region showed the lowest trabecular thickness and the highest value for the bone specific surface. The degree of anisotropy was lowest at the anterior mandible. The condyle showed thinner trabeculae with a more anisotropic arrangement than the other mandibular regions. Conclusion: There were microstructural differences between the regions of the maxilla and mandible. These results suggested that different mechanisms of external force might exist at each site.

• Journal of Yeungnam Medical Science
• /
• 제38권1호
• /
• pp.47-52
• /
• 2021

Background: Short stature is defined as a height below the 3rd percentile or more than two standard deviations below the mean for a given age, sex, and population. There have been inconsistent results regarding craniofacial morphology in short-statured children. This study aimed to analyze the differences between short-statured children with growth hormone deficiency, idiopathic short-statured children, and normal children. Methods: Thirty-one short-statured children with growth hormone deficiency, 32 idiopathic short-statured children, and 32 healthy children were enrolled in this study. The measurements of their craniofacial structures from lateral cephalograms were evaluated. Results: There were statistically significant differences among the three groups seven variables (anterior cranial base length, posterior cranial base length, total cranial base length, upper posterior facial height, posterior total facial height, mandibular ramus length, and overall mandibular length) in the linear measurement and five variables (saddle angle, gonial angle, mandibular plane angle, position of mandible, and maxilla versus mandible) in the angular measurement. Conclusion: Compared to the control group, many linear and angular measurements of the craniofacial structures were significantly different in the two short-statured groups (p <0.05). Treatment plans by orthodontists should include these craniofacial structure characteristics.

• 대한치과교정학회지
• /
• 제10권1호
• /
• pp.29-36
• /
• 1980

Inclined plane, one of frequently used orthodontic appliances, may cause posterior displacement of mandible and injure the normal growth of temporomandibular joint. So author carried out the mandibular posterior displacement experimentally induced by inserting inclined plane in the rat incisors in order to investigate the histological reactions occuring in the temporomandibular joint of experimental animals. Following results were obtained. 1. The posterior displacement of condyle resulted in the widening of anterior synovial space with anterior condylar hyperplasia and posterior condylar atrophy. In addition, tissue changes were more severe in young rats than in adult rats. 2. The tissue reactions were localized only to condylar head ana there were no evidence of traumatic features in young rats. In adult rats, hemorrhage was an additional finding 1 week after experiment. 3. The remodelling processes were accompanied by the increasing or reduction of fibrous layer and subsequent replacement by cartilage layer occured massively and abruptly in young rats, it occured slightly and slowly in adult rats. 4. The remodelling process of injured condyle occured from 1 week to 4 weeks after experiment and completed between 8 weeks after experiment.

• Journal of Oral Medicine and Pain
• /
• 제42권4호
• /
• pp.109-115
• /
• 2017

Purpose: This study analyzed the effects of digastric muscle injury on mandibular growth in young rats. Methods: Fourteen 4-week-old Wistar rats were divided into 3 groups; experimental group A (n=6) with unilateral (right) shortening of the posterior digastric muscle, experimental group B (n=6) with bilateral shortening of the posterior digastric muscles, and control group C (n=2) who underwent a sham operation. Eight weeks after the operation all animals were sacrificed and the outcomes were compared using body weight evaluation, mensurations on lateral radiograph of hemimandibles and histological evaluation. Results: There was no significant difference between groups A and B in body weight gain. Comparison of the mean values of hemimandible distance on radiograph was performed. The difference in group mean value of mandible-related distances was analyzed using the Wilcoxon test (rank sum test) and a comparison of the homonymous distances of group A and B was performed using the Mann-Whitney test. There were differences between sides in mandibular length in group B and mandibular ramus height and transverse width of the condyle in group A (all, p<0.05). There were differences in condylar height and mandibular length on the left side between groups A and B (p<0.05). Histologic examination of temporomandibular joint showed similar findings in all specimens. Conclusions: Injury of the posterior belly of the digastric muscle during the rat growth period induced shortening of mandibular ramus height and transverse width of the condyle. It can be inferred that trauma to the posterior belly of the digastric muscle affects horizontal and vertical growth of the mandible.

• Imaging Science in Dentistry
• /
• 제35권1호
• /
• pp.55-58
• /
• 2005

Ameloblastic fibro-odontoma is a rare benign mixed odontogenic tumor with histologic characteristics of ameloblastic fibroma and complex odontoma. As with ameloblastic fibroma, it may be asymptomatic or found because of painless swelling and delayed eruption of associated tooth. This report presents a case of ameloblastic fibro-odontoma in the posterior mandible of a 14-year-old girl and analyses its clinical features and radiographic features on plain X-ray film and CT images. (Korean J Oral Maxillofac Radiol 2005; 35 : 55-8)

• 대한치과교정학회지
• /
• 제5권1호
• /
• pp.33-41
• /
• 1975

To study the effect of the tetracycline-HCl on the growth of the rats, the author made a daily injection of tetracycline-HCl in the amount of 40mg/kg of body weight to the lactating mother and weanling rats for 7 days. Lactating and weanling young rats were killed at a week intervals and removed tibia and mandible from soft tissues. The effect of the tetracycline on the growth of rats were analysed from the weight, the length of tibia and the size of mandible. The results were as follows: 1. Tetracycline inhibited the growth of young rats. 2. Inhibitory effects were greater ill the weanling group than the lactating group. 3. The inhibitory effect was marked just after the injection of tetracycline-HCl in body weight and after a week in mandible and tibia. 4. The inhibitory effect of growth nab continued for 2-3 weeks in body weight and 3-4 weeks in tibia and mandible. 5. In growth of mandible, the antero-posterior growth was more inhibited than the vertical.

• 대한치과교정학회지
• /
• 제23권4호
• /
• pp.529-541
• /
• 1993

The purpose of this study was to investigate not only the variability in the timing and amount of the maximum pubertal spurt in cranial base and mandible, but also its interrelationship with the timing of peak height velocity. This study was carried out by analysing biannual serial lateral cephalometric radiographs of twenty-six males and twenty-one females who were taken from 8.5years to 16.5years old of mean age, according to the established land-marks and linear measurements. The results of this study were summarized as follows. 1. Prevalance of the maximum growth spurt more than 80 percentage was occurred in all measurements of cranial base and mandible, except posterior cranial base length in the female. 2. In all measurements of cranial base and mandible, the maximum spurt was occurred earlier in the female than the male while it was greater in male in all measurements except ramal height. 3. In body height measurement, the peak height velocity was occurred 2 years earlier for the female(11.0 years old) than the male(13.0 years old). 4. The timing of maximum spurt in anterior cranial base length and total mandibular length in both sexes and ramal height in the female were coincided with PHV. The maximum spurt was occurred in both sexes in all measurements 2 years before or after PHV, except mandibular body length and posterior cranial base length the in female. 5. In all ages, there was significant correlation between the total mandibular length and ramal height, and was also correlation between total cranial base length and anterior cranial base length(P<0.05). However, there was no significant correlation between the ramal height and mandibular body length. In addition, there was also no any correlation between the anterior cranial base length and posterior cranial base length in all ages(P>0.05).

• Journal of Periodontal and Implant Science
• /
• 제26권4호
• /
• pp.933-948
• /
• 1996

The purpose of this study was to examine the anatomic structures of the mandible-inferior alveolar canal, mental foramen, mental canal-with panoramic radiography and conventional tomography and to compare both radiographic techniques in conjunction with endosseous implants. In this study 14 adult dentulous mandibles -27 cases of right and left side of mandibles- were examined and the results were as follows. 1. The distance between superior border of the inferior alveolar canal and the alveolar ridge crest showed a decreasing tendency from the mental foramen to 4cm posterior to the mental foramen. 2. The mean diameter of the inferior alveolar canal was $4.11{\pm}0.50mm$ with panoramic radiography and $3.29{\pm}0.59mm$ with conventional tomography. 3. The inferior border of the inferior alveolar canal and inferior border of the mandible was closest at 2cm posterior to the mental foramen but it was not statistically significant. the mean distance was $1l.64{\pm}2.95mm$ in panoramic radiography and $1l.68{\pm} 2.91mm$ in conventional tomography. 4. The inferior alveolar canal located lingually in bucco-lingual direction 16%(mental foramen), 54%(lcm posterior to the mental foramen), 68%(2cm posterior to the mental foramen), 50%(3cm posterior to mental foramen), 55%(4cm posterior to the mental foramen). 5. Mean length of the anterior loop of the mental canal was 2.73mm, and the loop below 2mm was 35% and 15% of mental canal was invisible in panoramic radiography. 6. The minimum interforaminal distance was 56.7mm, the maximum distance was 73.2mm and the mean distance was 66.42mm in panoramic radiography. 7. The mean distance between midpoint of the mental canal and alveolar ridge crest was 16.24mm and the mean buccolingual angulation of the mental canal was $52.98^{\circ}$ in conventional tomography. 8. In comparison of panoramic radiography and conventional tomography, inferior alveolar canal is better visualized with conventional tomography than panoramic radiography from the mental foramen to the 2cm posterior to the mental foramen, while visiblity of conventional tomography prominently decreased in 4cm posterior to the mental foramen and alveolar ridge crest is better visualized with panoramic radiography than conventional radiography at the mental foramen and at 4cm posterior to the mental foramen. In radiologic examination of anatomic structures of the mandible for endosseous implants, panoramic radiography and conventional tomography can be effectively used when it is used to overcome the anatomic limitations.

• 대한치과보철학회:학술대회논문집
• /
• 대한치과보철학회 1999년도 Asian Academy of Prosthodntics. Korean Academy of Prosthodontics
• /
• pp.96.2-97
• /
• 1999