• The Journal of Korean Academy of Prosthodontics
• /
• v.40 no.3
• /
• pp.287-295
• /
• 2002

Statement of Problem. Endodontically treated teeth frequently required posts and cores to provide retention and resistance form for crowns. In spite of excellent mechanical properties of metal post and core, its metallic color can be detected through all ceramic restorations occasionally. To solve esthetic problems of metal post and core zirconia post system has been introduced recently. Purpose. The purpose of this study was to examine the fracture strength and mode of resin root analogs restored with zirconia, gold and titanium posts with resin, ceramic and metal cores after cementation with metal crowns. Materials and methods. To avoid the morphological variations of natural teeth, 40 root analogs were fabricated with composite resin. Forty resin root analogs were randomly assigned to four groups according to post and core materials: Group A: cast gold post and core and complete cast crowns, as control. Group B: titanium posts (Parapost, Coltent/Whaledent Inc., NJ, USA) and composite resin cores. Group C: zirconia posts (Cosmopost, Ivoclar AG, Schaan/Liechtenstein) and composite resin cores Group D: zirconia posts and heat-pressed ceramic cores (IPS Empress Cosmo Ingots, Ivoclar AG) After thermocycling ($5^{\circ}C{\sim}55^{\circ}C$, 30 sec.), cyclic loading was applied at 3mm below the incisal edge on the palatal surfaces at an angle of 135 degree to the long axis (2Hz, 50N, 50000cycles). Fracture strength was measured by universal testing machine (Instron, High Wycombe, UK) and fracture pattern of restored resin root analogs was also evaluated. Results and conclusion. Within the limitations of this study following results were drawn. 1. Resin root analogs restored with zirconia posts and composite resins demonstrated lowest fracture strength among tested groups. 2. There was no significant difference in the fracture strength between zirconia posts and heat pressed glass ceramic cores and cast gold posts and cores 3. The fracture strength of resin root analogs restored with titanium posts and composite resin cores was lower than that of gold posts and cores. 4. The deep oblique fracture lines were dominantly observed in root analogs restored with cast gold post and core and zirconia post and heat-pressed ceramic core groups.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.41
• /
• pp.33.1-33.7
• /
• 2019

Background: The concept of the ideal morphology for the alveolar bone form is an important element to reconstruct or restore the in maximizing esthetic profile and functional alveolar bone restoration. The purpose of this preliminary study is to evaluate the normal alveolar bone structure to provide the standard reference and guide template for use in diagnosing for implant placement, determining the correct amount of bone augmentation in actual clinical practice and producing prostheses based on three-dimensional imaging assessment of alveolar bone. Methods: This study was included 11 men and 11 women (average age, 22.6 and 24.5 years, respectively) selected from among 127 patients. The horizontal widths of alveolar bone of maxilla and mandible were measured at the crestal, mid-root, and root apex level on MDCT (multi-detector computed tomography) images reconstructed by medical imaging software. In addition, tooth dimensions of the central incisors, canines, second premolars, and first molars of maxilla and mandible, including the horizontal width of the interdental alveolar bone crest, were also measured and statistically analyzed. Results: The horizontal alveolar bone width of the palatal side of maxilla showed a distinct increment from the alveolar bone crest to the apical region in both anterior and posterior areas. The average widths of the maxillary alveolar ridge were as follows: central incisor, 7.43 mm; canine, 8.91 mm; second premolar, 9.57 mm; and first molar, 12.38 mm. The average widths of the mandibular alveolar ridge were as follows: central incisor, 6.21 mm; canine, 8.55 mm; second premolar, 8.45 mm; and first molar, 10.02 mm. In the buccal side, the alveolar bone width was not increased from the crest to the apical region. The horizontal alveolar bone width of an apical and mandibular border region was thinner than at the mid-root level. Conclusions: The results of the preliminary study are useful as a clinical guideline when determining dental implant diameter and position. And also, these measurements can also be useful during the production of prefabricated membranes and customized alveolar bone scaffolds.

• Journal of Periodontal and Implant Science
• /
• v.34 no.3
• /
• pp.563-572
• /
• 2004

Since bacterial plaque is known as the major cause of every oral disease, it is necessary to control plaque to maintain periodontal health. Although tooth brushing has been the typical method of plaque control, additional use of plaque control devices are necessary for cleansing interdental areas. Dental floss has been used for a long time as the additional plaque control device and proved to be effective. The newly developed embossed new dental pick is composed of elastic plastic material in form with its tip longer than other toothpick. In addition, as thickness of the tip gradually increases, it can be adapted easily with minimal trauma to interdental gingiva. The embossed tip can remove dental plaque easily, and the opposite end can approach lingual and palatal areas through triple angulation. Therefore, the authors studied the effect of embossed new dental pick and dental floss on periodontally involved 15 patient. The following results were obtained. 1. For embossed new dental pick, probing depth at baseline, 1 week, 4 weeks were $3.6{\pm}0.6mm$, $3.4{\pm}0.5mm$, $3.2{\pm}0.5mm$, respectively, and $4.2{\pm}0.9mm$, $4.1{\pm}0.9mm$, $4.0{\pm}0.9mm$, respectivly for clinical attachment level. 2. In case of embossed new dental pick, bleeding on probing at baseline, 1 week, 4 weeks were $43.0{\pm}4.4%$, $28.5{\pm}5.1%$, $22.2{\pm}5.6%$, respectively, and, at 1 week and 4 weeks, they were significantly different from that of dental floss. 3. Gingival index of toαhpick at baseline, 1 week, 4 weeks were $1.7{\pm}0.5$, $1.0{\pm}0.3$, $0.9{\pm}0.2$, respectively, and, $1.7{\pm}0.5$, $1.1{\pm}0.4$, $1.0{\pm}0.4$, respectively for plaque index, and $3.0{\pm}0.5$, $1.7{\pm}0.5$, $1.4{\pm}0.4$, respectively for proximal plaque index. proximal plaque index at 4 weeks was significantly different from that of dental floss. 4. The result of questionnaire showed that the two types of device were both satisfactory, however, embossed new dental pick had higher preference as well as satisfaction. As a result, embossed new dental pick is thought to be clinically effective for its simplicity and good accessibility.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.33 no.1
• /
• pp.99-102
• /
• 2006

Most supernumerary primary teeth erupt in the primary lateral incisor region and are reported to occur in 0.03 to 1.9% in the primary dentition. Most parents fail to recognize them because of their normal shape, eruption and exfoliation. Several theories have been proposed for the etiology of hyperdontia and the dental lamina hyperactivity theory is most widely accepted. When a supernumerary primary tooth develops, it is reported that there also exists a supplemental or rudimentary form of a succedaneous supernumerary tooth. Supernumerary primary teeth do not need specific treatment as 75% of them erupt and exfoliate normally Only periodic radiographic exams are necessary to find out whether there is any problem with the eruption of the succedaneous tooth. In the following two cases, a supplemental supernumerary primary tooth with a loss of the anterior developmental space was observed at the maxillary lateral incisor region. Radiographic examination revealed an impacted succedaneous supernumerary tooth at the palatal side of the supernumerary primary tooth.

• The korean journal of orthodontics
• /
• v.31 no.1 s.84
• /
• pp.25-38
• /
• 2001

The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear, The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal fortes that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed 'Avchiai Expansion Effect' 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, hut for the outer-bow 25mm and 35mn shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

• The korean journal of orthodontics
• /
• v.38 no.3
• /
• pp.187-201
• /
• 2008

Objective: The aim of this study was to determine whether cortical punching stimulates the expression of matrix metalloproteinase-1, -8, and -13 in orthodontic tooth movement in rats. Methods: A total of 32 male sprague-dawley rats at 15 weeks old were divided into two groups of 16 rats each, to form the tooth movement with cortical punching (TMC) group and tooth movement only (TM) group. A total of 20 gm of orthodontic force was applied to rat incisors to cause experimental tooth movement. Cortical punching was performed on the palatal side near the central incisor with a 1.0 mm width microscrew in the TMC group. The duration of tooth movement was 1, 4, 7, and 14 days. Results: Measurements of the mRNA expression were selected as the means to determine the identification of expression of MMP-1, -8, and -13. In the TMC group, the expression of collagen type I was greater than that of the TM group from day 4 to day 14. Expression of TIMP-1 in the TM group was greater than that of the TMC group in the pressure side of PDL and alveolar bone cell at day 4. In the TMC group, TIMP-1 was expressed at the osteoclast, but not at the tooth surface of the TM group at day 14, Maximum induction of the mRNA of MMP-1 was observed on day 4 in the TMC group, but it was observed on day 7 in the TM group. MMP-8 mRNA of the TMC group was twice greater than that of the TM group at f days. In the TMC group, maximum induction of MMP-13 mRNA was observed on day 1. Conclusions: These findings suggested that cortical punching can stimulate remodeling of PDL and alveolar bone connective tissues during experimental orthodontic tooth movement in rats.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.34 no.1
• /
• pp.140-149
• /
• 2007

Cleft lip and palate are congenital craniofacial malformation. Reconstruction of dental arch in patient with alveolo-palatal clefts is very important, because they have many problems in functions and esthetics. Malnutrition, poor oral hygiene, respiratory infections, speech malfunctions, maxillofacial deformity, and psychological problems may be occured without proper treatment during the long period of management of the cleft lip and palate. So the treatment should be managed with a multidisciplinary approach. Bone grafting is a consequential step in the dental rehabilitation of the cleft lip and palate patient A complete alveolar arch should be achieyed of the teeth to erupt in and to form a stable dentition. And the presence of the cleft complicate the orthodontic treatment. Therefore bone grafting in patients with cleft lip and palate is a widely adopted surgical procedure. Grafted bone stabilizes the alveolar process and allows the canine or incisor to move into the graft site. After the bone grafting, orthodontic closure of the maxillary arch has become a common practice for achieving dental reconstruction without any prosthodontic treatment. Various grafting materials have been used in alveolar clefts. Iliac bone is most widely fovoured, but tibia, rib, cranial bone, mandible have also been used. And according to its time of occurrence, the bone graft may be divided into primary, early secondary, secondary, late secondary. Bone grafting is called secondary when performed later, at the end of the mixed dentition. It is the most accepted procedure and has become part of treatment of protocol A secondary bone graft is performed preferably before the eruption of the permanent canine in order to provide adequate periodontal support for the eruption and preservation of the teeth adjacent to the cleft. In this report, we report here on a patient with unilateral cleft lip and palate, who underwent iliac bone graft. The cleft was fully obliterated by grafted bone in the region of the alveolar process. The presence of bone permitted physiologic tooth movement and the orthodontic movement of adjacent tooth into the former cleft area. Satisfactory arch alignment could be achieved in by subsequent orthodontic treatment.