• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.3
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• pp.153-159
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• 2019

Purpose: Aims to analyze the occlusal wear patterns in maxillary posterior teeth with palatal side abfractions and study the association between occlusal force and abfractions. Materials and Methods: This study was conducted in a total of 308 teeth from 148 patients with palatal side abfractions in maxillary posterior teeth. The occlusal wears in maxillary premolars and molars with palatal side abfractions were classified and recorded. The classification was done by type of teeth, age, and gender, and in order to evaluate the statistical significance between groups, chi-square test was conducted (${\alpha}=0.05$). Results: Palatal side abfractions in maxillary posterior teeth were observed at the highest frequency in the 1st molars, and in all teeth with palatal side abfractions, more than one occlusal wear was observed. In classification by type of teeth, by age, and by gender, the occlusal wears in teeth with palatal side abfractions were observed at high frequency in cuspal inclined plane, central fossa, and marginal ridge, and there was a statistical significance (P < 0.05). Conclusion: Palatal side abfractions were observed at the highest frequency in maxillary 1st molars, and in all maxillary posterior teeth where palatal side abfractions were found, the occlusal wears were observed. And the occlusal wears were observed at high frequency in cuspal inclined plane, central fossa and marginal ridge. Such results show that abfraction is associated with occlusal force.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.24-34
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• 2023

The aim of this study was to retrospectively analyze the effects of pulp treatment on exfoliation of primary teeth and its related factors. In this study, 167 teeth of 97 patients aged 6 months to 12 years who were treated with pulp treatment at Dankook Dental Hospital were selected, and information related to pulp treatment and tooth loss was collected. The included subjects were 72 primary anterior teeth (43.1%) and 95 primary posterior teeth (56.9%), of which 56 were males (57.7%) and 41 females (42.3%). The mean follow-up period was 106.1 ± 38.7 months, and the mean age at pulp treatment was 34.8 ± 15.4 months for primary anterior teeth and 69.1 ± 25.1 months for primary posterior teeth. Unilaterally pulpectomized teeth were significantly exfoliated earlier than the same tooth on the opposite side (p < 0.05). Also, in the case of teeth with periapical lesions, despite pulp treatment, the probability of extraction due to infection has been increased on primary anterior teeth (p < 0.05), but not on posterior teeth (p > 0.05). Pulpectomized teeth were lost earlier, an average of 7.8 months for primary anterior teeth and 8.5 months for primary posterior teeth. Early loss of the primary tooth can lead to space loss and premature eruption of the successor, so this can be considered when planning or performing treatment of the primary tooth.

• Journal of Oral Medicine and Pain
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• v.18 no.1
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• pp.107-117
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• 1993

The author has taken intraoral standard films by the paralleling technique of 6414 teeth in 838 patients ranged from early twenties to early sixties and analysed the change of pulp cavity in the mandibular posterior teeth by ageing. The obtined results were as follows : 1. There was no significant difference between the right and left teeth. 2. The degree of change of pulp cavity in female was higher than that in male. 3. The change of pulp cavity was increased by ageing. 4. The correlation between the degree of change of pulp cavity inmandibular posterior teeth (X) and age (Y) were : Male 1st premolar Y=13.22X3.37+ r=0.79 2nd premolar Y=12.09X+3.65 r=0.79 1st molar Y=11.90X+1.25 r=0.78 2nd molar Y=10.51X+10.43 r=0.83 Female 1st premolar Y=13.66X-2.49 r=0.86 2nd premolar Y=13.63X-2.42 r=0.86 1st molar Y=12.42X-1.44 r=0.79 2nd molar Y=11.42X+5.91 r=0.84

• Restorative Dentistry and Endodontics
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• v.42 no.3
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• pp.157-167
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• 2017

This systematic review aims to summarize the current clinical studies that investigated survival rates against fracture of endodontically treated posterior teeth restored with crowns or resin composite restorations. Literature search were performed using keywords. Publications from 1980 to 2016 were searched in PubMed, ScienceDirect, ISI Web of SCIENCE, MEDLINE, and SCOPUS. Included studies were selected based on inclusion and exclusion criteria. Three clinical studies were included: 1 randomized controlled trial and 1 prospective and 1 retrospective cohort studies. Pooled survival rates ranged from 94%-100% and 91.9%-100% for crowns and resin composite, respectively. The majority of teeth had no more than 3 surface loss of tooth structure. The studies included were heterogeneous, and were not appropriate for further meta-analysis. Current evidence suggested that the survival rates against the fracture of endodontically treated posterior teeth restored with crowns or resin composites were not significantly different in the teeth with minimum to moderate loss of tooth structure.

• The korean journal of orthodontics
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• v.47 no.1
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• pp.21-30
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• 2017

Objective: The aim of this study was to investigate the three-dimensional (3D) position of the center of resistance of 4 mandibular anterior teeth, 6 mandibular anterior teeth, and the complete mandibular dentition by using 3D finite-element analysis. Methods: Finite-element models included the complete mandibular dentition, periodontal ligament, and alveolar bone. The crowns of teeth in each group were fixed with buccal and lingual arch wires and lingual splint wires to minimize individual tooth movement and to evenly disperse the forces onto the teeth. Each group of teeth was subdivided into 0.5-mm intervals horizontally and vertically, and a force of 200 g was applied on each group. The center of resistance was defined as the point where the applied force induced parallel movement. Results: The center of resistance of the 4 mandibular anterior teeth group was 13.0 mm apical and 6.0 mm posterior, that of the 6 mandibular anterior teeth group was 13.5 mm apical and 8.5 mm posterior, and that of the complete mandibular dentition group was 13.5 mm apical and 25.0 mm posterior to the incisal edge of the mandibular central incisors. Conclusions: Finite-element analysis was useful in determining the 3D position of the center of resistance of the 4 mandibular anterior teeth group, 6 mandibular anterior teeth group, and complete mandibular dentition group.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.357-367
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• 1993

The purpose of this study was to evaluate the fracture strength of class II restored premolars with amalgam, posterior composite, amalgam - Ketac silver, resin - Ketac silver restorations at marginal ridge. Fifty extacted maxillary and mandibular premolar teeth that were caries free, fracture free, and restoration free were selected and randomly divided into five groups : Group 1 : 10 intact teeth, Group 2 : 10 teeth with class II cavities and restored with, amalgam, Group 3: 10 teeth with class II cavities and restored with posterior resin, Group 4 : 10 teeth with class II cavities and restored with amalgam - ketac silver, Group 5 : 10 teeth with class II cavities and restored with resin - Ketac silver. All teeth were mounted in base of dental stone within metal rings of 2cm diameter, exposing only the crown portion. Class II mesio - occlusal or disto - occlusal cavities were prepared into specimens of Group 2 through 5 by using a No. 710 fissure bur. The occlusal portion was prepared to a faciolingual width of 1.5mm and a pulpal depth of 1.5mm. The proximal protion was prepared to a faciolingual width of 4mm, a occlusogingival height of 4mm, and a gingival floor of 1.5mm. The teeth in Group 2 and 3 were resotored with silver amalgam apd posterior resin respectively. In Group 4 and 5, proximal portions were first filled with Ketac silver 1.5mm gingivally and remaining cavities were restored with amalgam and posterior resin respectively. All specimens were stored in 100 % relative humidity at $37^{\circ}C$ for 48 hours before testing. All teeth were subjected to a compressive load in a Universal Instron Testing Machine at marginal ridges. The loads required to fracture the restorations were recorded in killograms and the data obtained were subjected to statisticall analysis. The results were all follows : 1. The fracture strength of Group 1 which were unprepared were $100{\pm}10.1\;kg$ and the higher values than Group 2, 3, 4, 5 which were prepared and resotred. 2. In restored groups, Group 2 had the higher fracture strength($81.8{\pm}12.4\;kg$) than other groups and Group 4 had the lowest fracture strength($66.8{\pm}9.2kg$). 3. There were significant differences between fracture strength of between Group 1 and Group 3, 4, 5(P<0.05), but not significant difference between fracture strength of Group 2, 3, 4, 5(P>0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.2
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• pp.165-173
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• 2024

Restoring lost teeth is very important in terms of both function and aesthetics. If tooth loss occurs in the posterior region and the loss of support is persistent, it may cause a gradual shift in the position of the mandible and a change in occlusion. This clinical case attempted to restore support for the posterior teeth with a fixed prosthesis using implants in a patient whose opposing teeth were erupted and the occlusal plane collapsed due to long-term loss of the maxillary left posterior teeth and mandibular right first molars. To correct the occlusal plane of remaining dentition, wax-up of maxillary left posterior teeth was duplicated with acrylic resin and placed on maxilla. Surgical template for implant placement were fabricated using digital technology. After the support of the posterior teeth was restored with the placement of the implant, stable occlusion with temporary restorations was observed for a sufficient time. Afterwards, monolithic zirconia prosthesis was placed on the patient to ensure functional and aesthetic improvement.

• 대한치과교정학회:학술대회논문집
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• 1998.10a
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• pp.22-23
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• 1998

• The Korean Journal of Malacology
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• v.27 no.2
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• pp.91-97
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• 2011

This study examines the morphological features of larval and postlarval shells of the paedomorphic bivalve Crenella decussata Montagu, 1808 from the Sea of Japan. During the early morphogenesis of the shell of C. decussata the following characteristics appear: prodissoconch I -the anterior and posterior provincular teeth, a broad primary ligament pit located on the chondrophore; nepioconch - the anterior and posterior juvenile teeth,primary lateral teeth, fine commarginal and radial sculpture. Larvae of C. decussata distinctly differ from other mytilid larvae by a D-shaped shell, absence of umbo, astraight hinge margin, and homogeneous fine-grained sculpture without co-marginal lines of growth. These shell characters indicate lecithotrophic development of this species. Some morphostructures are revealed which might be used in crenellin taxonomy.

• The korean journal of orthodontics
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• v.46 no.2
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• pp.73-80
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• 2016

Objective: The purpose of this study was to investigate the static (SFF) and kinetic frictional forces (KFF) in sliding mechanics of hybrid bracket systems that involve placing a conventional bracket (CB) or active self-ligating bracket (ASLB) on the maxillary anterior teeth (MXAT) and a passive SLB (PSLB) on the maxillary posterior teeth (MXPT). Methods: The samples consisted of two thoroughbred types (group 1, anterior-CB + posterior-CB; group 2, anterior-ASLB + posterior-ASLB) and four hybrid types (group 3, anterior-CB + posterior-PSLB-type 1; group 4, anterior-CB + posterior-PSLB-type 2; group 5, anterior-ASLB + posterior-PSLB-type 1; group 6, anterior-ASLB + posterior-PSLB-type 2) (n = 13 per group). After maxillary dentition alignment and maxillary first premolars removal in the stereolithographically-made typodont system, a $0.019{\times}0.025$-inch stainless steel wire was drawn through the right quadrant of the maxillary arch at 0.5 mm/min for 5 min. The SFF and KFF were measured with a mechanical testing machine and statistical analyses were performed. Results: Four different categories of SFF and KFF were observed among all groups (all p < 0.001). Group 1 demonstrated the highest SFF and KFF; groups 4 and 3 were second and third highest, respectively. The fourth category included groups 2, 5, and 6. Placing PSLBs on the MXPT resulted in significant SFF and KFF reductions in cases with CBs on the MXAT, but not in cases with ASLBs on the MXAT. Conclusions: These data might aid in the development of a hybrid bracket system that enables low-friction sliding of an archwire through the MXPT.