• The korean journal of orthodontics
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• v.16 no.2
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• pp.53-67
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• 1986

The physical tooth movement by orthodontic force is based upon alveolar bone resorption at compression site and new bone formation at tension site of the alveolar socket. The function of the cyclic AMP is to participate not only in initial action of bone cells by mechanical forces but also in the continuous cellular response leading to bone remodelling. This experiment was performed to clarify the role of cyclic AMP in bone remodelling by mechanical force in the NORMAL group, the DIABETES group and the INSULIN TREATED group. The 72 rats were divided into the NORMAL group, the DIABETES group and the INSULIN TREATED group. The same orthodontic forces were applied to the rats of 3 groups. These rats were treated for periods of time ranging from 1 hour, 1 day, 7 days, 14 days, 21 days and 28 days. The samples of alveolar bones were obtained from compression and tension sites surrounding the tipping teeth from NORMAL, DIABETE and INSULIN TREATED rats. The samples were assayed for cyclic AMP by the cyclic AMP RIA kit. The results were as follows: 1. The cyclic AMP levels of alveolar bone in compression and tension sites showed initial decrease, then increased and .remained elevated by the time consuming. 2. The highest cyclic AMP level showed in the DIABETES group and the lowest level was in the NORMAL group. 3. The cyclic AMP levels in the INSULIN TREATED group was similar with the NORMAL group in control and tension sites, but in the compression sites it was similar with the DIABETES group.

• International Journal of Oral Biology
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• v.34 no.2
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• pp.53-59
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• 2009

Periodontal ligament (PDL) tissue is a connective tissue that is interposed between the roots of the teeth and the inner wall of the alveolar bone socket. PDL is always exposed to physiologic mechanical force such as masticatory force and PDL cells play important roles during orthodontic tooth movement by synthesizing and secreting different mediators involved in bone remodeling. The Wnt/${\beta}$-catenin signaling pathway was recently shown to play a significant role in the control of bone formation. In the present study, we applied cyclic tensile stress of 20% elongation to cultured human PDL cells and assessed its impact after six days upon components of the Wnt/${\beta}$-catenin signaling pathway. RTPCR analysis showed that Wnt1a, Wnt3a, Wnt10b and the Wnt receptor LRP5 were down-regulated, whereas the Wnt inhibitor DKK1 was up-regulated in response to these stress conditions. In contrast, little change was detected in the mRNA expression of Wnt5a, Wnt7b, Fz1, and LRP6. By western blotting we found decreased expression of the ${\beta}$-catenin and p-GSK-3${\beta}$ proteins. Our results thus show that mechanical stress suppresses the canonical Wnt/${\beta}$-catenin signaling pathway in PDL cells.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.225-230
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• 2008

Purpose: Many clinical studies have reported that higher success rates are achieved with teeth that have immature roots than other autotransplanted teeth that have more immature root. However, based on date published recently, the success rate of autotransplantation of teeth with complete root formation was higher. The purpose of this study was to examine the long term(2 to 6 years follow-up) success rate of autotransplantation of third molar with complete root formation and to discuss some conditions and prerequisites for success. Materials and Methods: 26 sites of 24 patients aged 26 to 55 (mean age 40.8) were autotransplanted with third molars with complete root formation. These cases were followed for 2 to 6 years after surgery. The success criteria included (1) no discomfort during functioning (2) absence of progressive root resorption and alveolar bone resorption. Result: Of 26 teeth 5 teeth were failed, therefore success rate is 81%(21/26 teeth). The results suggested that higher success rate is acquired from (1) extraction socket due to dental caries (2) mandibular recipient site (3) patient younger than 40 years old. Autotransplantation of third molar to replace molars with advanced periodontal disease also showed considerably high success rate(84%). Conclusion: With appropriate case selection, autotransplantation of third molar with complete root formation remains a viable alternative for replacing a missing molar tooth.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.8.1-8.6
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• 2018

Background: This study was to evaluate the effect of bone graft procedure on the primary stability of implants installed in fresh sockets and assess the vertical alteration of peri-implant bone radiographically. Methods: Twenty-three implants were inserted in 18 patients immediately after tooth extraction. The horizontal gap between the implant and bony walls of the extraction socket was grafted with xenografts. The implant stability before and after graft procedure was measured by Osstell Mentor as implant stability quotient before bone graft (ISQ bbg) and implant stability quotient after bone graft (ISQ abg). Peri-apical radiographs were taken to measure peri-implant bone change immediately after implant surgery and 12 months after implant placement. Data were analyzed by independent t test; the relationships between stability parameters (insertion torque value (ITV), ISQ abg, and ISQ bbg) and peri-implant bone changes were analyzed according to Pearson correlation coefficients. Results: The increase of ISQ in low primary stability group (LPSG) was 6.87 ± 3.62, which was significantly higher than the increase in high primary stability group (HPSG). A significant correlation between ITV and ISQ bbg (R = 0.606, P = 0.002) was found; however, age and peri-implant bone change were not found significantly related to implant stability parameters. It was presented that there were no significant peri-implant bone changes at 1 year after bone graft surgery. Conclusions: Bone graft procedure is beneficial for increasing the primary stability of immediately placed implants, especially when the ISQ of implants is below 65 and that bone grafts have some effects on peri-implant bone maintenance.

• Imaging Science in Dentistry
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• v.52 no.1
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• pp.75-82
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• 2022

Purpose: This cross-sectional study evaluated and categorized the tomographic sagittal root position (SRP) of the maxillary anterior teeth in a Brazilian population. Materials and Methods: Cone-beam computed tomographic scans of 420 maxillary anterior teeth of 70 patients (35 men and 35 women, mean age 25.2±5.9 years) were evaluated. The SRP was classified as class I, II, III, or IV. In class I, the root is positioned against the buccal cortical plate; in class II, the root is centered in the middle of the alveolar housing; in class III, the root is positioned against the palatal cortical plate; and in class IV, at least two-thirds of the root engage both the buccal and palatal cortical plates. Results: In total, 274 teeth (65.2%) were class I, 39 (9.3%) were class II, 3 (0.7%) were class III, and 104 (24.8%) were class IV. The frequency distribution over the teeth groups was different from the overall analysis. Important differences were found in the frequencies of classes I, II, and IV compared to other populations. Sex was not associated with the SRP classes (P=0.307). Age distribution was significantly different over the classes (P=0.004). Conclusion: The findings of this study on the distribution of SRP classes among the Brazilian population compared to other populations demonstrate that the SRP should be analyzed on a case-by-case basis for an accurate treatment plan in the maxillary anterior area.

• Journal of Periodontal and Implant Science
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• v.52 no.1
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• pp.3-27
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• 2022

Purpose: This study was conducted to evaluate and compare the effects of different graft materials used in alveolar ridge preservation on dimensional hard tissue changes of the alveolar ridge, assessed using cone-beam computed tomography (CBCT) scans. Methods: A systematic electronic search of MEDLINE and the Cochrane Central Register of Controlled Trials and a manual search were conducted from November 2019 until January 2020. Randomized controlled trials were included if they assessed at least 1 variable related to vertical or horizontal hard tissue changes measured using CBCT scans. After a qualitative analysis of the included studies, subgroups were formed according to the graft material used, and a quantitative analysis was performed for 5 outcome variables: changes in vertical alveolar bone height at 2 points (midbuccal and midpalatal/midlingual) and changes in horizontal (buccolingual) alveolar bone width at 3 different levels from the initial crest height (1, 3, and 5 mm). Results: The search resulted in 1,582 studies, and after an independent 3-stage screening, 16 studies were selected for qualitative analysis and 9 for quantitative analysis. The metaanalysis showed a significantly (P<0.05) lower reduction of alveolar ridge dimensions for the xenogenic subgroup than in the allogenic subgroup, both vertically at the midbuccal aspect (weighted mean difference [WMD]=-0.20; standard error [SE]=0.26 vs. WMD=-0.90; SE=0.22) as well as horizontally at 1 mm (WMD=-1.32; SE=0.07 vs. WMD=-2.99; SE=0.96) and 3 mm (WMD=-0.78; SE=0.11 vs. WMD=-1.63; SE=0.40) from the initial crest height. No statistical analysis could be performed for the autogenic subgroup because it was not reported in sufficient numbers. Conclusions: Less vertical and horizontal bone reduction was observed when xenogenic graft materials were used than when allogenic graft materials were used; however, the loss of alveolar ridge dimensions could not be completely prevented by any graft material.

• Restorative Dentistry and Endodontics
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• v.48 no.2
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• pp.16.1-16.11
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• 2023

Objectives: The aim of this study was to evaluate the influence of peak kilovoltage (kVp) and a metal artifact reduction (MAR) tool on image quality and the diagnosis of vertical root fracture (VRF) in cone-beam computed tomography (CBCT). Materials and Methods: Twenty single-rooted human teeth filled with an intracanal metal post were divided into 2 groups: control (n = 10) and VRF (n = 10). Each tooth was placed into the socket of a dry mandible, and CBCT scans were acquired using a Picasso Trio varying the kVp (70, 80, 90, or 99), and the use of MAR (with or without). The examinations were assessed by 5 examiners for the diagnosis of VRF using a 5-point scale. A subjective evaluation of the expression of artifacts was done by comparing random axial images of the studied protocols. The results of the diagnoses were analyzed using 2-way analysis of variance and the Tukey post hoc test, the subjective evaluations were compared using the Friedman test, and intra-examiner reproducibility was evaluated using the weighted kappa test (α = 5%). Results: The kVp and MAR did not influence the diagnosis of VRF (p > 0.05). According to the subjective classification, the 99 kVp protocol with MAR demonstrated the least expression of artifacts, while the 70 kVp protocol without MAR led to the most artifacts. Conclusions: Protocols with higher kVp combined with MAR improved the image quality of CBCT examinations. However, those factors did not lead to an improvement in the diagnosis of VRF.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.92-97
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• 2004

Traumatic injuries in the young peranent dentition are common, but root fractures, defined as fractures in volving dentin, cementum and pulp, are relatively uncommon. Case 1 is a 9-year-old boy who had a horizontal root fracture of his maxillary right central incisor in the apical third. Root canal therapy was performed in coronal segment and calcium hydroxide therapy was initiated. Six months after treatment, a periapical radiograph showed calcific tissue formation and normal root development. 1 year and 3 months later, the canal was permanently obturated with gutta-percha. Case 2 is a 7-year-old girl who had a vertical root fracture of her maxillary right central incisor. Fractured tooth was intentionally extracted atraumatically, and then the separated fragments are bonded with resin cement. the restored tooth was replanted into the original socket. Recalls up to 8 months showed normal mobility and no periapical pathosis. In these cases, we performed conservative treatment. Clinical and radiographic examination showed no pathosis or abnormality of the teeth and periodontal tissue.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.3
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• pp.262-269
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• 2011

Ameloblastic fibroma is rare true benign mixed odontogenic tumor. Most of these tumors occur in the posterior region of the mandible under 20 years of age. It develops generally associated with unerupted tooth and grows slowly on the surface of alveolar bone, therefore interferes normal tooth eruption. These lesions rarely showing a little bony expansion, are usually asymptomatic and are discovered incidentally on routine dental exam. It is similar to amleoblastic fibroodontoma and ameloblastic fibrodentinoma clinically and roentgenographically but represents no dental hard tissue formation histologically. Enucleation and curettage of surrounding bone are generally recommended options for treatment. Even though there are some reports of recurrence and malignant transformation and more aggressive treatment options like block resection are suggested sometimes, but in most cases, recurrence is unusual because it is well encapsulated and easily separated from adjucent bony socket. In these cases, we did conservative treatment such as enucleation and curettage to the patients who were visited for ameloblastic fibroma associated with delayed eruption of lower first molar. After regular check-ups, we found relatively natural eruption process of combined teeth.

• Journal of Periodontal and Implant Science
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• v.47 no.6
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• pp.372-380
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• 2017

Purpose: The aim of this prospective pilot study was to compare alveolar ridge preservation (ARP) procedures with open-healing approach using a single-layer and a double-layer coverage with collagen membranes using radiographic and clinical analyses. Methods: Eleven molars from 9 healthy patients requiring extraction of the maxillary or mandibular posterior teeth were included and allocated into 2 groups. After tooth extraction, deproteinized bovine bone mineral mixed with 10% collagen was grafted into the socket and covered either with a double-layer of resorbable non-cross-linked collagen membranes (DL group, n=6) or with a single-layer (SL group, n=5). Primary closure was not obtained. Cone-beam computed tomography images were taken immediately after the ARP procedure and after a healing period of 4 months before implant placement. Radiographic measurements were made of the width and height changes of the alveolar ridge. Results: All sites healed without any complications, and dental implants were placed at all operated sites with acceptable initial stability. The measurements showed that the reductions in width at the level 1 mm apical from the alveolar crest (including the bone graft) were $-1.7{\pm}0.5mm$ in the SL group and $-1.8{\pm}0.4mm$ in the DL group, and the horizontal changes in the other areas were also similar in the DL and SL groups. The reductions in height were also comparable between groups. Conclusions: Within the limitations of this study, single-layer and double-layer coverage with collagen membranes after ARP failed to show substantial differences in the preservation of horizontal or vertical dimensions or in clinical healing. Thus, both approaches seem to be suitable for open-healing ridge preservation procedures.