• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.371-379
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• 2008

The aim of this study was to evaluate the tightness of proximal tooth contact(TPTC) using a novel device at rest state on implant prostheses. Ten healthy young adults with class I normal occlusion consented to participate in the study and twenty patients were restored with a total 20 single-implant crowns in the left maxillary and mandibular second molars for 10 single-implant crowns, respectively. Test area were divided by 4 groups. UM describes the contact between the upper natural left first molar and natural second molar; LM the contact between the lower natural left first molar and natural second molar; IUM the contact between the upper natural left first molar and implant second molar and ILM the contact between the lower natural left first molar and implant second molar. The TPTC was measured at rest state in each area. The mean TPTC of the UM, LM, IUM and ILM was 1.48(${\pm}0.44$) N, 1.78(${\pm}0.40$) N, 1.14(${\pm}0.37$) N and 1.30(${\pm}0.32$) N respectively. These results indicate that the TPTC was less between natural tooth and implant prosthesis than between natural teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.4
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• pp.769-779
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• 1995

The understanding the nature of occlusal tooth contacts of natural dentition is important for correct diagnosis and treatment of diseases developed in stomatognatic system. Several investigator have studied the distribution of tooth contacts in maximum intercuspation and have repored contact locations with respect to the tooth position. However, there are few report the variation of the occlusal contact point with change in each head position. This study analysed the number of occlusal contact point with change in each head position. 30 subject(male 17, female 13), who ahad natural occlusion and no symptoms of temporomandibular disorder, were selected. The numbers and patterns of tooth contact were recorded by silicone bite registration on stone model at four different head positions with head anguration gauge(from the supine to the upright position). The results obtained were as follows : 1. The numbers of total occlusal contact point on teeth increased to average 25, 29, 35, 42 points as head angulation was changed from the supine to the upright position against the ala-tragus line, and there was significant difference(P<0.05). 2. In the 19 subject(65%)of total 30 subject, the perforated point of the silicone bite indicated that the locus for the prime contact point moved mesially as the head angulation was changed from the supine to the upright position. 3. On the basis of the fact that the anterior occlusal contact point increase as head angulation changed from the supine to the upright position, we could find that the mandibular position is moved anteriorly.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.23-37
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• 1991

The understanding the natureof occlusal tooth contacts of natural dentition is important for correct diagnosis and treatment of diseases developed in stomatognatic system. Several investigator have studied the distribution of tooth contacts in maximum intercuspation and have reported contact locations with respect to the tooth position. Many methods have been clinically applied for the occlusal analysis in the intercuspal position. However, there are few quantative methods. This study analyzed the new software version of the T-Scan system to record and analyze occlusal contact balance in the anterior-posterior and right-left directions. Six time moment statistics and five moment statistics were calculated in the midsagittal and the incisal axes of the occlusal plane. In the present study, informed consent was obtained from 100 subjects with natural dentitions. The results were as follows ; 1. The mean of the dental arch length & width were 48.78, 65.32mm in whole population, 49.09mm, 65.50mm in males, 48.78mm, 64.63mm in females, respectively. 2. The mean of TLR & PLR were 0.193mm(left), 0.311mm(left), respectively. Therefore, the distribution of tooth contacts was bilaterally symmetric. 3. The mean of TFB & PFB were 29.168mm, 29.055mm, and that of LFB & RFB were 29.627mm, 29.587mm, respectively, and the qualitative center of occlusal contacts was the firtst molar. 4. The mean of LL & RL were 31.666mm, 31.377mm, respectively, and the quantitative center of occlusal force was the first molar. 5. The mean of LF & RF were 60.237N, 59.276N, respectively and Left-right moment was 72.491Nmm. Therfore, the distribution of occlusal force was bilaterally balanced.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.223-235
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• 1998

The recognition of the esthetics as well as their function of the teeth in the dental field is growing. Evaluating the esthetics of a tooth concerns shape, texture, and color. And among these, color has been the most difficult element to make natural expression. Color is a very subjective element affected by many different factor like light source, object, observer. Numerous efforts to quantifying color has been made. Currently the use of colorimeter and spectrophotometercolor that the color measuring device has been suggested. In this study, the normal range of the tooth color in canines, lateral incisors and central incisors for Koreans was evaluated with a modified spectrophotometer for intraoral use. The color differences in terms of teeth positions, age and area within the tooth was evaluated and comparatively analyzed. Results were as follow ; 1. In all age groups, the central incisors are most bright and least yellowish opposit to the canines are most dark and yellowish. The central incisors and lateral incisors showed the similar color patterns. 2. In the comparison between gender, it showed that in the 10' s group male have more yellowish, the 20's female have lighter and more redness, the 30's indicated more redness in female and in the 40's the lightness is more in female. 3. With aging, there was no significant change in $L^*$ and $a^*$ coordinates but a shift was in $b^*$ to yellowish in the 30' sand 40's in central incisors. Lateral incisors and canines showed a lighter and more yellowish tooth color with an irregular change of color coordinate in $a^*$. 4. In all teeth the middle and cervical portion showed close correlation with over 0.7(0.05>p) but color ($a^*$, $b^*$) showed higher correlation than lightness($L^*$). 5. It has been shown that through the regression test the cervical color could be calculated by the middle color value.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.399-408
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• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.

• Journal of Oral Medicine and Pain
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• v.23 no.4
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• pp.457-473
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• 1998

This study was performed to investigate the morophological and positional correlation between the upper cervical vertebra, the oral structures and the pharyngeal tissues, and the correlation of these anatomical structures with dental features, such as teeth wear area nad tooth contact status, etc. Seventy patients with temporamandibular disorders and sixty three dental students without any signs and symptoms in head and neck region were selected for this study. All they had natural dentition without any fixed and removable protheses. Teeth wear area and arch width wre measured from the upper dental cast, tooth contact status were observed by T-Scan system$^\textregistered$ and four cephaloradiograpohs were taken from four head postures, namely, natural(NHP), forward(FHP), upward(UHP), and downward head postiure(DHP). 22 cephalometric items were measured on the films and the data were processed with SAS statistical program. The result of this study were as follows : 1. In normal group, angle of cervical vertebra tangent and of between hard and soft palate were broader in female subjects than those in male subjacets, but distance from subocciput to axis, size of soft palate, and pharyngeal space width were larger in male subjects. 2. In normal group with natural head posture, the items correlated each others from the three anatomical regions were distance between first nad second vertebra in posterior part, distance from the lingual surface of lower anterior teeth to anterior surface of soft palate, and distance from the hyoid bone to third vertebra. 3. Three set of items showed significant correlation each other in the four head postures in normal group. First set was the angle between hard and soft palate and the idstance from subocciput to posterior arch of first vertebra, second set was the distance between first and second vertebra in posterior part and the teeth wear area, third set was number and force of tooth contact and length of soft palate and distance from anterior tip of hyoid bone to mandibular plane.

• The Journal of Advanced Prosthodontics
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• v.11 no.3
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• pp.187-192
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• 2019

PURPOSE. The purpose of this in vitro study was to investigate the fracture loads and modes of failure for the full range of natural teeth under simulated occlusal loading. MATERIALS AND METHODS. One hundred and forty natural teeth were taken from mandibles and maxillas of patients. There were 14 groups of teeth with 10 teeth in each group (5 males and 5 females). Each specimen was embedded in resin and mounted on a positioning jig, with the long axis of the tooth at an inclined angle of 30 degrees. A universal testing machine was used to measure the compression load at which fracture of the tooth specimen occurred; loads were applied on the incisal edge and/or functional cusp. RESULTS. The mean fracture load for the mandibular first premolar was the highest (2002 N) of all the types of teeth, while the mean fracture load for the maxillary first premolar was the lowest (525 N). Mean fracture loads for the mandibular and maxillary incisors, and the first and second maxillary premolars, had significantly lower values compared to the other types of teeth. The mean fracture load for the teeth from males was significantly greater than that for the teeth from females. There was an inverse relationship between age and mean fracture load, in which older teeth had lower fracture loads compared to younger teeth. CONCLUSION. The mean fracture loads for natural teeth were significantly different, with dependence on tooth position and the sex and age of the individual.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.127-133
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• 2017

The purpose of this study is to confirm the effect of natural tooth whitening using fruits that can be easily accessed in real life by increasing interest in tooth whitening in modern society. Twenty premolar teeth were divided into five groups (n=4). Strawberry (A), lemon (B), banana skin (C), baking soda (D) and whitening toothpaste (E) were treated with a toothbrush on the enamel surface. The tooth surface was treated with a toothbrush at the same time for 3 minutes for breakfast, lunch, and dinner, then washed with sterile distilled water, and stored in saline solution. This procedure was repeated for 4 weeks, and the color change of teeth was observed at intervals of one week. After 4 weeks, there was a significant difference in tooth color change after 3 weeks(p<0.05). Among them, strawberry and lemon showed higer effects to whitening toothpaste. It is believed that strawberries and lemons have a higher whitening effect than whitening toothpaste. Whitening toothpaste may be replaced with a safe natural whitening effect using strawberries and lemons instead of chemical ingredients that may be harmful to human body.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.3
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• pp.287-293
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• 2011

The enamel, the upper layer of a tooth has remarkable capability of bearing severe loading on the tooth. The fracture behavior is important to understand the mechanism of load bearing and it could be very useful for developing new materials. Non-destructive evaluation of such materials will also benefit from this knowledge. The graded microstructures of enamel were modeled by finite element analysis software and the J-integrals and the stress intensity factors were evaluated as the fracture parameters. The results show that these parameters are location dependent. Those values increase when measured in the direction of dentine enamel junction. This finding matched well with experiments and implies many useful understanding of biomaterials and applications to new materials.

• The Journal of the Korean dental association
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• v.48 no.4
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• pp.288-296
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• 2010

Although non-surgical endodontic procedures have high success rates, failures do occur, These can be managed by root canal re-treatment or surgical intervention. Intentional replantation is an accepted endodontic treatment procedure in which a tooth is extracted and treated outside the oral cavity and then inserted into its socket to correct an obvious radiographic or clinical endodontic failure. Intentional replantation is indicated when other endodontic treatments performed to maintain the tooth have failed, or when endodontic periradicular surgery is not feasible. Intentional replantation may be particularly useful in these cases because these difficult to access areas can be maximally treated while the tooth is out of the mouth without damaging the periodontal attachment in adjacent teeth. In conclusion, intentional replantation is a reliable and even predictable procedure, and should be considered more often as a treatment modality in our efforts to maintain the natural dentition.