• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.181-192
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• 1997

The difficulty of endodontic retreatment depends on various factors and it is affected by retention of post. In this experiment, root canal therapy was done in extracted human teeth and cut into 10mm length from the root apex, and then cemented by zinc phosphate cement, Vitremer$^{(R)}$(glass ionomer) luting cement and Panavia 21$^{(R)}$(resin cement). Post preparation was done by #4 Parapost drill at 6mm length and cement was inserted by lentulo spiral. After 24 hours, tensile bond strength, post removal time was measured after the ultrasonic application and the separation site was measured. The following results were obtained. 1. In measuring tensile bond strength, there is no statistical difference between zinc phosphate cement and Panavia 21$^{(R)}$, but Vitremer$^{(R)}$ showed lower value compared with those two cements. (p<0.001) 2. When the post removal time was measured after ultrasonic application, significant different value in order of Panavia 21$^{(R)}$, zinc phosphate cement and Vitremer$^{(R)}$ was shown. (p<0.001) 3. As a result of examining the separating site of each cement, all 16 of zinc phosphate cement group showed the fracture site between cement and post, Vitremer$^{(R)}$ was 13/16, and Panavia 2$^{(R)}$ was 8/16. In case of tooth restoration using Parapost, the use of Panavia 21 showed good retention property than Vitremer$^{(R)}$, but when retreatment is needed the difficulty of post removal will be increased.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.334-346
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• 1997

Incidence of using esthetic composite resin in the posterior area is increasing but there were lots of inconsistent reports about their microleakage and marginal adaptation. The purpose of this study was to evaluate the differences of microleakage and marginal adaptation according to restorative techniques. 30 cavities with enamel gingival margin were prepared and restored with 3 types of composite resin [Z-100($Scotchbond^{TM}$ MP), AELITEFIL ($Onestep^{TM}$), Her culite XRV(Fuji BOND LC)] in direct technique and another 30 cavities were restored with preformed CR inlays and 3 different modern resin and resin-modified GI cements (Superbond C&B, Choice, Fuji Duet). Samples were chemically stressed in 75% ethanol for 24 hours and were thermocycled (5-$55^{\circ}C$(500 times. The degree of microleakage through proximal and gingival margins was examined by 1 % MB dye and the degree of marginal adaptation by examining the margins via SEM. The following results were obtained ; 1. In direct groups, Herculite XRV [Fuji BOND LC, 35.13 (15.50) %] group showed statistically different, less microleakage than Z-100 [$Scotchbond^{TM}$ MP, 72.91 (16.91 %] group and AELITEFIL [One-step, 93.73 (13.66) %] group (p<0.05). 2. In indirect groups, the degree of microleakage in Mean(S.D.) were: Super bond C & B [39.00 (24.35) %], Choice [57.19 (33.80) %], Fuji Duet [58.22 (40.36) %]. But there was no significant difference. 3. There was no significant difference between resin cement and resin-modified GI cement. 4. There were gaps at the interface with the tooth structure, but no gap was seen at the interface with restoration in all specimens. 5. In direct groups, Herculite XRV(Fuji BOND LC) group made little gap compared with other groups, but 40-$50{\mu}m$ thickness of bonding agent, Fuji BOND LC, looked like a cement used in indirect technique. 6. All indirect groups showed a variety of cement thickness, from less than $20{\mu}m$ to over $100{\mu}m$ and that dimension of buccal/lingual margin was less than that of gingival margin.

• The Journal of Advanced Prosthodontics
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• 제8권6호
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• pp.489-493
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• 2016

PURPOSE. This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS. Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to $45^{\circ}$ oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (${\alpha}=.05$). RESULTS. The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION. For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.

• The Journal of Advanced Prosthodontics
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• 제11권6호
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• pp.324-330
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• 2019

PURPOSE. The aim of the study was to evaluate and compare the fracture resistance and modes of fracture of monolithic zirconia crowns with two preparation designs. MATERIALS AND METHODS. Forty human maxillary first premolar teeth were extracted for orthodontic purposes and divided into two main groups (n=20): Group A: monolithic traditional zirconia; Group B: monolithic translucent zirconia. The groups were further subdivided into two subgroups (n=10): (A1, B1) shoulder margin design; (A2, B2) feather-edge margin design. Teeth were prepared with either a 1 mm shoulder margin design or a feather-edge margin design. The prepared teeth were scanned using a digital intraoral scanner. The crowns were cemented using self-adhesive resin cement. All cemented teeth were stored in water for 7 days and thermocycling was done before testing. All samples were subjected to compressive axial loading until fracture. The fractographic analysis was done to assess the modes of fracture of the tested samples. RESULTS. The highest mean values of fracture resistance were recorded in kilo-newton and were in the order of subgroup A1 (2.903); subgroup A2 (2.3); subgroup B1 (1.854) and subgroup B2 (1.523). One-way ANOVA showed a statistically significant difference among the 4 subgroups. Concerning modes of fracture, the majority of samples in subgroups A1 and B1 were fracture of restoration and/or tooth, while in subgroups A2 and B2, the majority of samples fractured through the central fossa. CONCLUSION. Even though all the tested crowns fractured at a higher level than the maximum occlusal forces, the shoulder margin design was better than the feather-edge margin design and the monolithic traditional zirconia was better than the monolithic translucent zirconia in terms of fracture strength.

• 구강회복응용과학지
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• 제30권4호
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• pp.329-338
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• 2014

치주질환이나 우식으로 인해 구치부 치아가 상실된 환자들은 잔존하고 있는 전치부 및 소구치부 치아로 안정된 교합고경을 유지하기 어렵다. 구치의 상실로 대합치의 정출이나 인접치의 경사가 발생되는 경우 교합평면이 붕괴되거나 부적절한 교합간섭을 야기하게 된다. 만약 치아 상실 상태가 지속된 경우에는 하악의 전방이동으로 인해 상악 전치의 동요와 순측 이개를 초래하게 되며 치주질환이 동반된 경우에는 더욱 심각한 상황으로 변화한다. 이와 같이 치아의 병적 이동이 일어난 환자의 치료는 보존 및 치주치료, 교정 치료를 통한 재배열, 그리고 상실된 치아의 보철수복을 통한 교합 고경의 재설정 및 유지와 같은 다과간 협력 진료가 매우 중요하다.

• 한국재료학회지
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• 제23권3호
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• pp.168-176
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• 2013

In this study, hydroxyapatite (HAp) was incorporated into toothpaste and its effect on the remineralization and restoration of dental enamel was evaluated. Different sets of toothpaste were incorporated with HAp levels of 0%, 5%, 10 %, and 15 %. The filler particles of the resulting toothpaste samples were observed via SEM and XRD and compared with compositions of several commercially available toothpastes, showing that the HAp was successfully incorporated into the toothpaste samples. Different sets of human enamel were inflicted with lesions and then treated with the different fabricated toothpaste samples for five minutes three times a day for seven days. During the treatment, the teeth were subjected to demineralization and remineralization cycles to simulate the effect of natural saliva. The surface of the enamel samples were observed using SEM before and after one week of treatment, showing the formation of HAp layers on the surfaces of the enamel samples. The effect of the toothpaste on the lesions was observed using an inverted light microscope and the lesion depth was found to decrease as the concentration of HAp in the toothpaste used increased. HAp was successfully incorporated in the toothpaste and its presence was found to lessen lesion depths and improve tooth remineralization.

• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.393-398
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• 2001

Polymerization of light-activated restorations results in temperature increase caused by both the exothermic reaction process and the energy absorbed during irradiation. Within composite resin, temperature increases up to 2$0^{\circ}C$ or more during polymerization. But, insulation of hard tissue of tooth lowers this temperature increase in pulp. However, many clinicians are concerned about intrapulpal temperature injury. The purpose of this study was to evaluate temperature changes in the pulp according to various restorative materials and bases during curing procedure. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece fissure bur. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn below restorative materials for evaluating of temperature changes. This thermocouple was connected to temperature-recording device(Multiplication analyzer MX, 6.000, JAPAN). Temperature changes was evaluated from initial 37.$0^{\circ}C$ after temperature changes to 37.$0^{\circ}C$. Tip of curing unit was placed in the center of prepared cavity separated 1mm from restorative materials. Curing time was 40s. The restorative materials were used with Z 100, Fuji II LC, Compoglass flow and bases were used with Vitrebond, Dycal. Resrorative materials were placed in 2mm. The depth of bases were formed in 1mm and in this upper portion, resin of 2mm depth was placed. This procedure was performed 10 times. The results were as follows. 1. All the groups showed that the temperature in pulp increased as curing time increased 2. The temperature increase of glass ionomer was significantly higher than that of Resin and Compomer during curing procedure (P<0.05). 3. The temperature increase in glass ionomer base was significantly higher than that of Calcium hydroxide base during Resin curing procedure (P<0.05).

• Restorative Dentistry and Endodontics
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• 제37권1호
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• pp.41-49
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• 2012

Objectives: The internal adaptation of composite restorations with or without resin modified glass ionomer cement (RMGIC) was analyzed non-destructively using Microcomputed tomography (micro-CT). Materials and Methods: Thirty intact human teeth were used. The specimens were divided into 3 groups. In the control group, the cavities were etched with 10% phosphoric acid for 15 sec. Composite resin was filled into the cavity without adhesive. In group 1, light cured glass ionomer cement (GIC, Fuji II LC, GC) was applied as a base. The cavities were then etched, bonded, light cured and filled with composites. In group 2, the cavities were then etched, bonded, light cured and filled with composites without base application. They were immersed in a 25% silver nitrate solution. Micro-CT was performed before and after mechanical loading. One-way ANOVA with Duncan analysis was used to compare the internal adaptation between the groups before or after loading. A paired t-test was used to compare internal adaptation before and after mechanical loading. All statistical inferences were made within the 95% confidence interval. Results: The silver nitrate solution successfully penetrated into the dentinal tubules from the pulp spaces, and infiltrated into the gap between restoration and pulpal floor. Group 2 showed a lower adaptation than the control group and group 1 (p < 0.05). There was no significant difference between the control group and group 1. For all groups, there was a significant difference between before and after mechanical loading (p < 0.05). Conclusions: The internal adaptation before and after loading was better when composites were bonded to tooth using adhesive than composites based with RMGIC.

• 대한소아치과학회지
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• 제23권2호
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• pp.401-414
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• 1996

The purpose of this study was to compare the marginal leakage of resin liner which was used as a liner to amalgam restoration. Control group composed of no liner group, copalite group and experimental group composed of All-bond 2, Vitrebond, Superbond D-liner applied groups were evaluated. Cl.V preparation with a size of $3{\times}2{\times}1.5mm$ on 70 extracted primary molars were made and applied appropriate liners for each groups. After amalgam filling and polishing, polished specimens underwent temperature changed from $5^{\circ}C\;to\;55^{\circ}C$ a thousand times. After thermocycling, specimens were placed in 2% methylene blue dye solution for 72 hours in an incubator set at $37^{\circ}C$. The teeth were sectioned buccolingually and the degree of dye penetration was observed with a spectroscopy. (${\times}30$) The following results were obtained. 1. Vitrebond, All-bond 2, Superbond D-liner group exhibited a statistically significant lower degree of dye penetration than no liner and copalite group. (Kruskal-Wallis analysis, P<0.05) 2. No liner group and copalite group exhibited a similar degree of dye penetration. (Mann-Whitney analysis, P>0.05) 3. All-bond 2 group exhibited a statistically significant lower degree of dye penetration than Vitrebond group, (Mann-Whitney analysis, P<0.05) Superbond D-liner group also exhibited a lower degree of dye penetration than Vitrebond group but was statistically insignificant. (Mann-Whitney analysis, P>0.05)

• Journal of Periodontal and Implant Science
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• 제36권1호
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• pp.139-146
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• 2006

Many factors have been implicated in the etiology of gingival recession, including faulty toothbrushing, the position of the tooth in the arch(malalignment), the presence of inflammation, frenal attachment, impingement of restoration margins, orthodontic treatment and trauma from occlusion. Among the many factors, this study was to evaluate the relationship of occlusion and gingival recession. 640 teeth without other etiologic factors of gingival recession were evaluated in 40 subjects aged 21-59 years. Only 1st, 2nd premolar and molar were included in this study. We recorded nonworking contacts, working contacts, cervical abrasion, sex, gingival recession and evaluated that relation of occlusion and gingival recession. The results of this study were as follows; 1. Teeth with nonworking contacts were significantly more gingival recession than teeth without nonworking contacts.(p<0.01) 2. Teeth with working contacts were significantly more gingival recession than teeth without working contacts.(p<0.01) 3. Teeth with cervical lesion were significantly more gingival recession than teeth without cervical lesion.(p<0.01) 4. Men's teeth were more gingival recession than women's teeth but it was not significant.(p>0.01)