• 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 the Korean Association of Oral and Maxillofacial Surgeons
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• v.38 no.2
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• pp.71-77
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• 2012

Objectives: This study sought to investigate the positioning of the posterior superior alveolar artery in relation to the performance of the maxillary sinus bone graft procedure in a Korean population. Materials and Methods: We identified the position of the posterior superior alveolar artery relative to 93 maxillary sinuses in 58 patients and determined the distance from the inferior border of the artery in the premolar and molar areas to the alveolar ridge and sinus floor. Results: The mean distance from the alveolar ridge to the posterior superior alveolar artery in the dentate group ($20.62{\pm}3.05mm$ in the premolar region, $17.50{\pm}2.84mm$ in the molar region) was greater than as compared to the edentulous group ($18.83{\pm}2.79mm$ in the premolar region, $15.50{\pm}1.64mm$ in the molar region), and this difference was statistically significant (P<0.05). In contrast, there was no statistically significant difference (P>0.05) between the mean distance from the sinus floor to the posterior superior alveolar artery in the dentate group ($8.21{\pm}2.79mm$ in the premolar region, $7.52{\pm}2.07mm$ in the molar region) or in the edentulous group ($7.75{\pm}3.31mm$ in the premolar region, $7.97{\pm}2.31mm$ in the molar region). Conclusion: Prior to surgery, it is important to evaluate the position of the posterior superior maxillary artery by using computed tomography scans. The premolar area is safer than the molar area for performing the maxillary sinus bone graft without bleeding.

• Journal of Periodontal and Implant Science
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• v.44 no.2
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• pp.50-56
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• 2014

Purpose: The aims of this study were to measure the distance of the intraosseous vascular anastomosis in the anterolateral wall of the maxillary sinus from different reference points, and to correlate the location of the intraosseous vascular anastomosis with the tooth position and the residual bone height of the maxilla. Methods: Computed tomography (CT) images were taken from 283 patients undergoing dental implants placement in the posterior maxilla. Three horizontal lines were drawn at the ridge crest, maxillary sinus floor, and the position of the anastomosis. A vertical second line at the center of each tooth was drawn perpendicular to the horizontal lines. The distance from the ridge crest to the maxillary sinus floor and the distance from the maxillary sinus floor to the bony canal were measured from the intersections of the horizontal and vertical lines. The residual alveolar bone height was used to categorize three groups: group 1,<4 mm; group 2, between 4 and 8 mm; and group 3, >8 mm. Results: The residual bone height values of different tooth positions were significantly different (P=0.0002). The distance from the maxillary sinus floor to the intraosseous vascular anastomosis was significantly different between groups 1 and 3 (P=0.0039). At the molar sites, a moderate negative correlation was found between the residual bone height and the distance from the maxillary sinus floor to the intraosseous anastomosis. The distances of the alveolar ridge crest and the maxillary sinus from the intraosseous vascular anastomosis were not significantly different between sexes. Conclusions: Within the limitations of this study, sites with a higher residual bone height in the molar regions were at a relatively high risk of artery damage during window osteotomy preparation; therefore, we recommend taking more precautions when using a lateral approach for sinus elevation.

• Journal of Periodontal and Implant Science
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• v.50 no.3
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• pp.197-206
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• 2020

Purpose: The aim of this study was to determine the impact of different compressive forces on deproteinized bovine bone mineral (DBBM) particles covered by native bilayer collagen membrane (NBCM) during alveolar ridge preservation (ARP) in the molar area, and to identify any histomorphometric and clinical differences according to the compressive force applied. Methods: Sockets were filled with DBBM after tooth extraction, and different compressive forces (30 N and 5 N, respectively) were applied to the graft material in the test (30 N) and control (5 N) groups. The DBBM in both groups was covered with NBCM in a double-layered fashion. A crossed horizontal mattress suture (hidden X) was then made. A core biopsy was performed using a trephine bur without flap elevation at the implant placement site for histomorphometric evaluations after 4 months. The change of the marginal bone level was measured using radiography. Results: Twelve patients completed the study. The histomorphometric analysis demonstrated that the mean ratios of the areas of new bone, residual graft material, and soft tissue and the implant stability quotient did not differ significantly between the groups (P>0.05). However, the mean size of the residual graft material showed a significant intergroup difference (P<0.05). Conclusions: The application of 2 compressive forces (5 N, 30 N) on particulate DBBM grafts during open-healing ARP in the posterior area led to comparable new bone formation, implant feasibility and peri-implant bone level.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.310-322
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• 2016

Objective: The aim of this study was to determine the optimal loading conditions for pure intrusion of the six maxillary anterior teeth with miniscrews according to alveolar bone loss. Methods: A three-dimensional finite element model was created for a segment of the six anterior teeth, and the positions of the miniscrews and hooks were varied after setting the alveolar bone loss to 0, 2, or 4 mm. Under 100 g of intrusive force, initial displacement of the individual teeth in three directions and the degree of labial tilting were measured. Results: The degree of labial tilting increased with reduced alveolar bone height under the same load. When a miniscrew was inserted between the two central incisors, the amounts of medial-lateral and anterior-posterior displacement of the central incisor were significantly greater than in the other conditions. When the miniscrews were inserted distally to the canines and an intrusion force was applied distal to the lateral incisors, the degree of labial tilting and the amounts of displacement of the six anterior teeth were the lowest, and the maximum von Mises stress was distributed evenly across all the teeth, regardless of the bone loss. Conclusions: Initial tooth displacement similar to pure intrusion of the six maxillary anterior teeth was induced when miniscrews were inserted distal to the maxillary canines and an intrusion force was applied distal to the lateral incisors. In this condition, the maximum von Mises stresses were relatively evenly distributed across all the teeth, regardless of the bone loss.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.422-441
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• 1993

The purpose of this study was to compare effects of the bioceramics on healing processes of the alveolar bone defects in dogs. Five adult dogs aged 1 to 2 years were used in this study. Experimental alveolar bone defects were created surgically with a #1/2 round bur at the furcation area of the buccal surface of the mandibular 3rd, 4th premolars and 1st molar. Fifteen experimental alveolar bone defects were devided into three groups according to the type of graft materials. The groups were as follows : 1) flap operation with dense hydroxyapatite( DHA group ) 2) flap operation with porous hydroxyapatite( PHA group ) 3) flap operation with natural coral ( NC group ) At 1, 2, 4, 6, and 12 weeks, dogs were serially sacrificed and specimens were prepared with Hematoxylin-Eosin stain and Mallory stain for light microscopic evaluation. The results of this study were as follows : 1. In every group, inflammatory cell infiltrations were seen at 1st weeks due to surgical trauma, however inflammatory response owing to graft materials were not seen. 2. In every group, the appearance of connective tissue around graft materials was loosely formed at the initial stages, however the connective tissue was densely formed at 2 weeks. 3. The presence of osteocytes were observed at 2 weeks in the natural coral group, however the osteocytes were appeared at 6weeks in the dense hydroxyapatite group. 4. A new bone was formed from the base and walls of the defect and gradually expanded toward the graft materials. 5. A resorption of the natural coral occurred irregularly at the periphery of the material, therefore the size and shape of the natural coral were reduced at 6 weeks. 6. At 12 weeks, the porous hydroxyapatite and natural coral were surrounded by newly formed bone most completely, however dense hydroxyapatite was surrounded by newly formed bone in part.

• The korean journal of orthodontics
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• v.14 no.2
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• pp.187-202
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• 1984

There are evidences that exogenous electric currents are capable of enhancing bone formation and resolution, and that the conversion of the bioelectric response to biochemical activity provides the directional component of orthodontic tooth movement. In addition, evidence has implicated cyclic nucleotides in alveolar bone cellular activation mechanism during orthodontic tooth movement. In view of these evidences, this study was performed to investigate the effects of exogenous electric currents on cyclic nuclotide levels in feline alveolar bone and the possible clinical application of electric currents as an additional orthodontic tool. In the first study, three groups of three adult cats were subjected to application of a constant direct current of $10{\pm}2$ microamperes to gingival tissue near maxillary canine noninvasively for 1, 3, and 7 days respectively. In the second study, three groups of three adult cats each were treated by an electric-orthodontic procedure for 1, 3, and 7 days respectively. The left maxillary (control) canine received an orthodontic force of 80gm alone at time of initiation, while the right maxillary (experimental) canine received combined force-electric stimulation (80gm of force and $10{\pm}2$ microamperes of a constant D.C. currents). Alveola, bone samples were obtain from the mesial (tension and/or cathode) and the distal (compression and/or anode) sites surrounding maxillary canines as well as from contralateral control sites. The samples were extracted, boiled, homogenized, and the supernatants were assayed for cyclic nucleotides (cAMP, cGMP) by a radioimmunoassay method. And also the amount of tooth movement was measured in the second study. On the basis of this study, the following conclusions can be drawn: 1. The fluctuation pattern of cyclic nucleotide levels in alveolar bone treated by exogenous electric currents was similar to that treated by orthodontic force. 2. The cAMP levels in alveolar bone of electrically treated teeth significantly elevated above the control values. And of electrically treated teeth, the values of the anode sites were higher than those of the cathode sites. 9. The cGMP levels in alveolar bone of electrically treated teeth elevated above the control values at the initiation phase of treatment, but dropped below the control values at time of termination. And of electrically treated teeth, the values of the cathode sites were higher than those of the anode sites. 4. The rate of tooth movement in teeth . treated by force-electric combination increased with the length of treatment as compared to that treated by mechanical force alone.

• The korean journal of orthodontics
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• v.14 no.1
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• pp.65-81
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• 1984

In order to observe the responses of the periodontal tissue on the tension side following the experimental tooth movement, 35 Guinea pigs were divided into the control group (5 animals) and 6 experimental groups (3 movement groups and 3 retention groups) consisting of each 5 animals. The experimental tooth movement of Guinea pig's upper incisors installing open helical loop were carried out by rendering continuous force : 5g (1st groups) 35g (2nd groups), 100g (3rd groups), respectively for 7 days. 3 movement groups (15 animals) were sacrificed soon after the continuous force, and 3 retention groups (15 animals) were sacrificed after the retention period of another 7 days. The following results were obtained from the observation of the surrounding tissues of teeth on the tension side through light microscopy any transmission electron microscopy. 1. The vessel walls in the experimental groups were thinner than those of the control group, the number of blood vessel had the tendency to increase. The greater the strong force applied to each group, the more the destruction of cells and fibers was found and the more the number of the red blood cell of vessel outside appeared. 2. New collagen fibers were produced from fibroblasts in the 1st groups (light force), but were produced rather less in the 2nd groups (medium force) and the 3rd groups (heavy force). 3. In the forming patterns of the new alveolar bone of the 3rd groups (heavy force), the bone trabeculae were formed towards the direction of the force to be applied, but the new alveolar bone in the 1st groups (light force) was produced evenly throughout the all surfaces of the alveolar bone rather than the patterns of bone trabeculae ; therefore, the patterns of new alveolar bone were observed differently according to the magnitude of the force applied. 4. In the retention group, it was observed that the collagen fibers were produced from the osteoblasts in the marginal areas of the periodontal ligaments being widely opened and were deposited on the alveolar bone surface but the production of collagen fibers from the osteoblasts in the other area of the periodontal ligaments was almost ceased, and a rest line on the new alveolar bone surface was found.

• The korean journal of orthodontics
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• v.40 no.5
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• pp.314-324
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• 2010

Objective: The purpose of this study was to determine differences of mandibular anterior alveolar bone thickness and symphysial cross sectional area in 9 different horizontal and vertical facial types. Methods: By using the initial cephalometric radiographs of 270 adult patients (male 135, female 135), the authors measured the buccolingual thickness of anterior alveolar bone on the basis of the root axis and symphysial cross sectional distance. Results: The high angle group showed significantly thinner buccolingual alveolar bone width except for the CEJ area and lingual alveolar bone width ($p$ < 0.05). The low angle group and Class I, II average group showed similar or significantly thicker alveolar bone width than the Class I average group ($p$ < 0.05). The Class III average group showed significantly thinner buccolingual and lingual alveolar bone width than Class I and II average groups ($p$ < 0.05). The Class III high angle group showed minimal alveolar bone width in all facial skeletal types. No significant difference was found in the symphysial cross sectional area of the different vertical facial skeletal types ($p$ > 0.05). Conclusions: The results of this study found that Class III high angle patients have thinner mandibular anterior alveolar bone thickness; therefore, more attention will be needed to determine the incisor position during orthodontic treatment for this group of patients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.1
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• pp.28-39
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• 2007

The purpose of this study is to evaluate the regenerative capacity of reconstruction in the atrophied posterior maxilla by comparing bone graft procedures and alveolar distraction osteogenesis (ADO) techniques. We performed the autogenous iliac bone graft (AGB group, 5 specimens in 3 patients), and the combination (Mixed group, 3 specimens in 3 patients) of the autogenous and deproteinized bovine bone ($Bio-Oss^{(R)}$, Geistlich Co., Switzerland) as the ratio of 2:1 in the sinus floor elevation procedures. ADO procedures using $TRACK^{(R)}$ (KLS Martin Co., Germany) were also performed to augment vertical alveolar height in atrophied posterior maxilla (ADO group, 5 specimens in 4 patients). Newly generated bone tissues were obtained with the 2.0mm diameter trephine bur (3i Co., USA) during implant fixture installation after 5-7 months. Routine histolomorphological observation, immunodot blot assay for quantitative evaluation, and immunohistochemical staining with antibodies to MMP-1, -9, -10, TIMP-1, -2, and BMP-2, -4 were all carried out. Lamellar bone formation was well shown in all specimens and new bone formations of ADO group increased than those of other procedures. In immunohistochemical staining, the strong expression of BMP-2 was shown in all specimens, and immunodot blot assay showed that bone formation is accompanied by the good induction of factors associated with angiogenesis and appeared more increased amount of osteogenic and angiogenic factors in ADO group. ADO is the most effective technique for new bone formation compared to sinus floor elevation with autogenous or mixed bone graft in the atrophied posterior maxilla. In the quantitative immunodot blot assay, the regenerated bone after ADO showed more increased products of VEGF, BMP-2, PCNA and MMP-1 than those after the other procedures, and these findings were able to be confirmed by immunohistochemical stainings.