Effect of platelet-rich plasma on bone regeneration in ovariectomized osteoporotic rats / 대한치과보철학회지

PURPOSE: The aim of this experimental study is to observe the effect of platelet-rich plasma (PRP) on early bone regeneration of rats both in normal condition and in osteoporosis induced by ovariectomy. MATERIAL AND METHODS: Total 40 Sprague-Dawley female rats were divided into 4 groups. A 8-mm-diameter calvarial critical-sized defect (CSD) was made by drilling with trephine at the center of calvaria in cranium of every rat. Every CSD was augmented with an osteoconductive synthetic alloplastic substitute (MBCP(TM)) and PRP as follows. Group A; 10 non-ovariectomized rats grafted with only MBCP(TM). Group B; 10 non-ovariectomized rats grafted with MBCP(TM)and PRP. Group C; 10 ovariectomized rats grafted with only MBCP(TM). Group D; 10 ovariectomized rats grafted with MBCP(TM) and PRP. At 4 weeks after graft, every rat was sacrificed. And histomorphometric analysis was performed by measuring calcified area of new bone formation within the CSD. RESULTS: Comparing four groups, results were obtained as follows. 1. In non-ovariectomized groups, PRP showed a positive effect somewhat but not significant (P > .05). 2. In ovariectomized groups, PRP showed a positive effect significantly (P .05). CONCLUSION: Within the limitation of this study, it can be concluded that PRP in combination with an osteoconductive synthetic alloplastic substitute has an effect on bone regeneration more significantly in ovariectomized osteoporotic rats than in normal rats.

The effect of silane treatment timing and saliva contamination on shear bond strength of resin cement to porcelain / 대한치과보철학회지

STATEMENT OF PROBLEM: Porcelain veneers have become a popular treatment modality for aesthetic anterior prosthesis. Fitting porcelain veneers in the mouth usually involve a try-in appointment, which frequently results in salivary contamination of fitting surfaces. PURPOSE: An in vitro study was carried out to investigate the effect of silane treatment timing and saliva contamination on the resin bond strength to porcelain veneer surface. MATERIAL AND METHODS: Cylindrical test specimens (n = 360) and rectangular test specimens (n = 5) were prepared for shear bond test and contact angle analysis. Whole cylindrical specimens divided into 20 groups, each of which received a different surface treatment and/or storage condition. The composite resin cement stubs were light-polymerized onto porcelain adherends. The shear bond strengths of cemented stubs were measured after dry storage and thermocycling (3,000 cycles) between 5 and 55 degrees C. The silane and their reactions were chemically monitored by using Fourier Transform Infrared Spectroscopy analysis (FTIR) and contact angle analysis. One-way analysis of variance (ANOVA) and Dunnett' multiple comparison were used to analyze the data. RESULTS: FT-IR analysis showed that salivary contamination and silane treatment timing did not affect the surface interactions of silane. Observed water contact angles were lower on the saliva contaminated porcelain surface and the addition of 37 percent phosphoric acid for 20 seconds on saliva contaminated porcelain increased the degree of contact angle. Silane applied to the porcelain, a few days before cementation, resulted in increasing the bond strength after thermocycling. CONCLUSION: Within the limitation of this study, it can be concluded that it would be better to protect porcelain prosthesis before saliva contamination with silane treatment and to clean the contaminated surface by use of phosphoric acid.

Screw Joint Stability under Cyclic Loading of Zirconia Implant Abutments / 대한치과보철학회지

PURPOSE: The purpose of this study was to evaluate the effect of abutment material on screw-loosening before and after cyclic loading. Among the different materials of abutments, zirconia and metal abutment were used. MATERIAL AND METHODS:: Two types of implant systems: external butt joint (US II, Osstem Implant, Korea) and internal conical joint (GS II, Osstem Implant, Korea) were used. In each type, specimens were divided into two different kinds of abutments: zirconia and metal (n = 5). The implant was rigidly held in a special holding to device ensure fixation. Abutment was connected to 30 Ncm with digital torque gauge, and was retightened in 30 Ncm after 10 minutes. The initial removal torque values were measured. The same specimens were tightened in 30 Ncm again and held in the cycling loading simulator (Instron, USA) according to ISO/FPIS 1480. Cycling loading tests were performed at loads 10 to 250 N, for 1 million cycles, at 14 Hz, (by subjecting sinusoidal wave from 10 to 250 N at a frequency of 14 Hz for 1 million cycles,) and then postload removal torque values were evaluated. RESULTS: 1. In all samples, the removal values of abutment screw were lower than tightening torque values (30 Ncm), but the phenomenon of the screw loosening was not observed. 2. In both of the implant systems, initial and postload removal torque of zirconia abutment were significantly higher than those of metal abutment (P .05). 4. In metal abutments, the removal torque ratio of GS II system (internal conical joint system) was lower than that of US II system (external butt joint system) (P .05). CONCLUSION: Zirconia abutment had a good screw joint stability in the condition of one million cycling loading.

Effect of surface treatmet on the shear bond strength of a zirconia core to veneering ceramic / 대한치과보철학회지

PURPOSE: The purpose of this research was to evaluate the shear bond strength between zirconia core and veneer ceramic after surface treatment. MATERIAL AND METHODS: Zirconia cores (N = 40, n = 10, 10 mm x 10 mm x 3 mm) were fabricated according to the manufacturers??instructions and ultrasonically cleaned. The veneering ceramics (thickness 3 mm) were built and fired onto the zirconia core materials. Four groups of specimens with different surface treatment were prepared. Group I: without any pre-treatment, Group II: treated with sandblasting, Group III: treated with liner, Group IV: treated with sandblasting and liner. The shear bond strength was tested in a universal testing machine. Data were compared with an ANOVA and Scheffe post hoc test (P = .05). RESULTS: The shear bond strength of group VI was significantly higher than the other groups. CONCLUSION: Both mechanically and chemically treated simultaneously on zirconia core surface influenced the shear bond strength between the core and veneering ceramic in all-ceramic systems.

The effect of fluoridation on discoloring of bleached teeth / 대한치과보철학회지

STATEMENT OF PROBLEM & PURPOSE: To study the effect of different fluoridation methods after in-office bleaching on the color of teeth during severe staining with coffee. MATERIAL AND METHODS: 44 specimens were randomly divided into four groups. Group 1 (no bleaching, no fluoride, coffee) was served as control for the influence of coffee on the color of untreated teeth. Group 2, 3 and 4 were undergone bleaching with 35% H2O2 for 30 minutes a day on 3 consecutive days. Group 2 was remained without fluoridation. Group 3 and 4 were fluoridated for 1 hour with either Cavity shield(R) or pH 7 Gel(R). All of groups were immersed in coffee solution for 7 days. Color determination was accomplished using the spectrophotometer (VITA Easyshade(R)). RESULTS: Delta L and Delta h increased, whereas Delta C decreased in the bleached groups. Pairwise comparisons with Tukey's HSD showed that there were statistically significant differences for Delta L and Delta h between the bleached groups and the non-bleached group (P .05). Also there were no statistically significant differences for Delta L, Delta C and Delta h between the group 3 treated with Cavity shield(R) and the group 4 treated with pH 7 Gel(R) (P > .05). CONCLUSION: It was concluded that fluoridation was not beneficial to the prevention of extrinsic stains after bleaching.

Effects of activators contained in adhesives on dentin bond strengths / 대한치과보철학회지

STATEMENT OF PROBLEM: An incompatibility between the initiator systems of self-curing composite resins and light-curing adhesives was supposed recently. PURPOSE: The purpose of the study was to evaluate the influence of activators for self/dual bonding on dentin shear bonding strengths. MATERIAL AND METHODS: Fifty human molars were divided into 5 groups. A flat dentin surface was created for each tooth. A self-curing composite resin (Luxacore) was bonded with the following adhesives (n = 10): One-Step, Prime and Bond NT, AdheSE, Prime and Bond NT and AdheSe were also used in combination with activators. Shear bond strengths were measured after 24 hours of water storage. The specimens were loaded in shear in the Instron until failure at a 1 mm/min crosshead speed. Data were compared using one-way ANOVA and Tukey HSD test (alpha = 0.05). RESULTS: The dentin adhesive systems in order of decreasing median bond strength were One-Step > Prime & Bond NT with activator, AdheSe with activator > Prime and Bond NT, AdheSe. Among adhesives, One-Step had the highest bond strength. Prime & Bond NT with activator had higher bond strengths than Prime and Bond NT that was used alone, and so was AdheSe. CONCLUSION: Shear bond strengths were increased in Prime and Bond NT and AdheSe when these were used with activators comparing used without activators. But using activators was not effective clinically comparing One-Step.

The color stability of aesthetic restorative materials resulting from accelerated aging / 대한치과보철학회지

STATEMENT OF PROBLEM: The discoloration of anterior teeth restoration is one of the material problems demanding retreatment. OBJECTIVES: To evaluate the color stability and affecting factors on esthetic restorative materials when subjected to accelerated aging. MATERIAL AND METHODS: This study was conducted using porcelain disks (IPS Empress 2-glazed, IPS Empress 2-polished), direct restorative resin disks (SYNERGY Duo) and indirect restorative resin disks (Sinfony, TESCERA ATL). Accelerated aging was done by precipitating the specimens in 38 degrees C distilled water and irradiating with xenon light, and the total irradiation was 397.98 KJ/mm. Color and microhardness change of the specimens were measured before accelerated aging and after 100 hours, 200 hours and 300 hours of accelerated aging, and Surface of the specimens were examined with SEM before and after 300 hours of accelerated aging. RESULTS: 1. After 300 hours' accelerated aging, a delta E value was 3.3 or lower in IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony. 2. After 300 hours' accelerated aging, gloss was lost and surface changes including microcracks were observed in TESCERA ATL and SYNERGY Duo, and color changes of them ranged between 3.58 and 6.40 delta E units. 3. During 300 hours' accelerated aging, the microhardness of surface was increased by 3.21 - 19.64 percent in all kinds of composites resin. CONCLUSION: After 300 hours' accelerated aging, SEM images IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony showed little morphological change and their color changes were considered to be clinically acceptable. And there was significant correlation between microhardness changes and color changes of composites (P < .05).

Comparison of retentive forces of temporary cements and abutment height used with implant-supported prostheses / 대한치과보철학회지

STATEMENT OF THE PROBLEM: Recent data regarding the effects the cement type and abutment heights on the retentive force of a prosthetic crown are inconsistent and unable to suggest clinical guidelines. PURPOSE OF THE STUDY: This study evaluated the effects of different types of temporary cements and abutment heights on the retentive strength of cement-retained implant-supported prostheses. MATERIALS AND METHODS: Prefabricated implant abutments, 4 mm in diameter, 8degrees taper per side, and light chamfer margins, were used. The abutment heights of the implants were 4 mm, 5.5 mm and 7 mm. Seven specimens of a single crown similar to a first premolar were fabricated. Six commercially available temporary cements, TempBond, TempBond NE, Cavitec, Procem, Dycal, and IRM, were used in this study. Twenty-four hours after cementation, the retentive strengths were measured using a universal testing machine with a crosshead speed of 0.5 mm/min. The cementation procedures were repeated 3 times. The data was analyzed using two-way analysis of variance and a Tukey test (alpha=0.05). RESULTS: The tensile bond strength ranged from 1.76 kg to 19.98 kg. The lowest tensile strengths were similar in the TempBond and Cavitec agents. Dycal showed the highest tensile bond strength (P<0.01). More force was required to remove the crowns cemented to the long abutments (P<0.05). CONCLUSION: TempBond and Cavitec agents showed the lowest mean tensile bond strength. The Dycal agent showed more than double the tensile bond strength of the TempBond agent.

Removal torque and bone formation of orthodontic miniscrew implant / 대한치과보철학회지

STATEMENT OF PROBLEM: An orthodontic miniscrew implant has been used as a skeletal anchorage for orthodontic treatment. However, any relation among the influence of the cortical bone, morphologic differences of orthodontic miniscrew implants and new bone formation hasn't been made clear yet. PURPOSE: The purpose of this study was to evaluate whether the orthodontic miniscrew implant could work as an intraoral skeletal anchorage immediately and stably for orthodontic treatment after insertion of it. MATERIAL AND METHODS: Two types of orthodontic miniscrew implants were used in this experiment; tapered type and straight type. One hundred and sixty eight orthodontic miniscrew implants were inserted into the tibiae of 21 rabbits and sacrificed on 3, 7, 11, 14, 21 and 28days later after insertion of them to study removal torque values and histologic and histomorphometric analyses. RESULTS: The results were as follows. 1. The removal torque values of the tapered type were higher than those of the straight type in all groups(p<0.05). 2. There wasn't any distinguishing differences between the tapered type and the straight type about the new bone formation percentage. 3. The removal torque values for both the tapered type and the straight type were gradually decreased at early stages of the test but started to increase at the 7 days group of the straight type and the 11 days group of the tapered type. 4. New bone formation percentage was increased gradually for both the tapered and the straight types as time passed(p<0.05). 5. It was found that the tapered type showed lower values in the cortical bone about both the maximum equilibratory stress distribution and the maximum principal stress distribution than the straight type in linear finite elements analysis. CONCLUSION: According to the research, the removal torque values were decreased at 7 days group of the tapered type and 11 days group of the straight type after the insertion of the orthodontic miniscrew implants in tibiae of rabbits. Considering the human bone activity, it is better to apply the orthodontic force 3.4 weeks later than to apply it immediately after the insertion of orthodontic miniscrew implants. Considering that general orthodontic force is about 250.500 grams, the tapered type can be worked as a stable skeletal anchorage in an orthodontic treatment even if the orthodontic force is applied on it immediately after the insertion of it.

Bone response of three different surface implants : Histomorphometric, perio test value and resonance frequency analysis in beagle dogs / 대한치과보철학회지

STATEMENT OF PROBLEM: The intial stability for osseointegration of implant has been an interesting factor. Especially, in the case of poor bone quality or immediately loaded implant, various strategies have been developed focusing on the surface of materials to improve implant fixation to bone. The microscopic properties of implant surfaces play a major role in the osseous healing of dental implants. PURPOSE: The aims of this study are to perform a histologic and histomorphometric comparison of the healing characteristics of three different surfaces and the comparison of resonance frequency analysis (RFA) values measured by Osstell(TM) and perio-test values (PTV) measured by Periotest. MATERIAL AND METHODS: A total of 24 screw titanium implants (Dentium Co., Seoul, Korea) with 6mm in length and 3.4mm in diameter, were placed in the mandible of 4 beagle dogs. Implants were divided into three groups following the surface treatment methods: Group I is machined(control group). Group II is anodically oxidized. Group III is coated 500nm in thickness with hydroxyapatite(HA) by ion beam assisted deposition(IBAD) on the anodized oxidization. Bone blocks from 2 dogs were caught after 3 weeks of covered healing and another blocks from 2 dogs after 6 weeks. RFA values and PTV were measured right after insertion and at 3 and 6weeks. Histomorphometric analysis was made with Kappa Image Base System to calculate bone-to-implant contact (BIC) and bone area inside the threads. Pearson's correlation analyses were performed to evaluate the correlation between RFA and PTV, BIC and bone area ratio of three different surfaces at 3 and 6 weeks. RESULTS: 1) In all surface treatment methods, the RFA values decreased and the PTV values increased until 6 weeks in comparison to initial values. 2) At 3 weeks, no significant difference was found from bone-to-implant contact ratio and bone area ratio of three different surface treatment methods(P>0.05). However, at 6 weeks, different surface treatment methods showed significantly different bone-toimplant contact ratio and bone area ratio(P<0.05). 3) In the implants with the IBAD on the anodic oxidization, significant difference was found between the 3 weeks and the 6 weeks bone area ratio(P<0.05). 4) Correlation was found between the RFA values and the bone area ratio at 3 and 6 weeks with significant difference(P<0.05). CONCLUSIONS: These results indicate that the implants with the IBAD on the anodic oxidization may have a high influence on the initial stability of implant.

Bone response of two different surface titanium subperiosteal implants: anodized surface, ibad ha coating surface / 대한치과보철학회지

STATEMENT OF PROBLEM: In case of poor bone quality or immediately loaded implant, various strategies have been developed focusing on the surface of materials to improve direct implant fixation to the bone. The microscopic properties of implant surfaces play a major role in the osseous healing of dental implant. PURPOSE OF STUDY: This study was undertaken to evaluate bone response of ion beam-assisted deposition(IBAD) of hydroxyapatite(HA) on the anodized surface of subperiosteal titanium implants. MATERIAL AND METHODS: Two half doughnut shape subperiosteal titanium implants were made. The control group was treated with Anodized surface treatment and the test group was treated with IBAD of HA on control surface. Then two implants inserted together into the subperiosteum of the skull of 30 rats and histological response around implant was observed under LM(light microscope) and TEM(transmission electron microscope) on 4th, 6th and 8th week. RESULTS: Many subperiosteal implants were fixed with fibrous connective tissue not with bony tissue because of weak primary stability. The control group observed poor bone response and there was no significant change at any observation time. However the test group showed advanced bone formation and showed direct bone to implant contact under LM on 8th week. The test group observed much rER in the cell of osteoblast but the control group showed little rER under TEM. CONCLUSIONS: The test group showed better bone formation than the control group at the condition of weak primary stability. With these results IBAD surface treatment method on Anodized surface, may be good effect at the condition of weak primary stability.

Effect of surface treatment methods on the shear bond strength of resin cement to zirconia ceramic / 대한치과보철학회지

STATEMENT OF PROBLEM: The aims of the study were to evaluate the effect of current surface conditioning methods on the bond strength of a resin composite luting cement bonded to ceramic surfaces and to identify the optimum cement type. MATERIAL AND METHODS: The sixty zirconia ceramic specimens(10 per group) with EVEREST milling machine and 60 tooth block were made. The zirconia ceramic surface was divided into two groups according to surface treatment: (1) airborne abrasion with 110micrometeraluminum oxide particles; (2) Rocatec system, tribochemical silica coating. The zirconia ceramic specimens were cemented to tooth block using resin cements. The tested resin cements were Rely X ARC, Panavia F and Superbond C and B. Each specimen was mounted in a jig of the universal testing machine for shear strength. The results were subjected to 2-way ANOVA and Post hoc tests was performed using Tukey, Scheffe, and Bonferroni test. RESULTS: The mean value of shear bond strength(MPa) were as follows: RelyXARC(+Al2O3),5.35+/-1.69; RelyXARC(+Rocatec),8.50+/-2.13; PanaviaF(+Al2O3),9.58+/-1.13; PanaviaF(+Rocatec),12.98+/-1.71; Superbond C and B(+Al2O3),8.27+/-2.04; Superbond C and B(+Rocatec),14.46+/-2.39. There was a significant increase in the shear bond strength when the ceramic surface was subjected to the tribochemical treatment(Rocatec 3M) in all cement groups(P<0.05). Bonding strengths of cements applied to samples treated with Al2O3 were compared; Rely X ARC showed the lowest values, whereas Panavia F cement showed higher value than that of Superbond C and B group with no statistical significance. When the bond strength of cements with Rocatec treatment was compared, Rely X ARC showed lowest values. Overall, it was apparent that tribochemical treated Super-Bond possessed higher mean bond strength.(14.46MPa; P<0.05) than that of Panavia F cement group with no significance. CONCLUSIONS: Silica coating followed silanization(Rocatec treatment) increase the bond strength between resin cement and zirconia ceramic. Panavia F containing phosphate monomer and Superbond C and B comprised of 4-META tend to bond chemically with zirconia ceramic, thus demonstrating higher bond strength compared to BisGMA resin cement. Superbond C and B has shown to have highest value of bonding strength to zirconia ceramic after Rocatec treatment compared to other cement.

Removal torque of bicortically stabilized RBM(resorbable blast media) pin implants in rabbit tibia / 대한치과보철학회지

STATEMENT OF PROBLEM: The use of small diameter implants having less than 3 mm in diameter were restricted because of lack of bonding strength to bone. PURPOSE: The purpose of this study was to observe how much resorbable blast media pin implants increase the binding force to the bone compared to machined transitional pin implants by measuring removal torque, and whether they can be used as final implants for replacement of small diameter teeth. MATERIAL AND METHOD: Fifteen rabbits were used in this study. Two kinds of implants (resorbable blast media pin implants and machined transitional pin implants) were inserted in each tibia bicortically. After healing time of 2, 4 and 8 weeks, the removal torque values were recorded and the rabbits were sacrificed for histological analysis. Linear finite element method analyses were conducted to compare bicortical fixation with monocortical fixation. RESULT AND CONCLUSION: Within the limitation of this in vivo study, the following conclusions were drawn: 1) The removal torque value of RBM pin implants showed statistically significant increase compared to machined pin implants at 2, 4, and 8 weeks respectively (p<0.05). 2) The removal torque value of RBM pin implants at 2, 4, and 8 weeks was increased statistically significantly with time (p<0.05). 3) Bicortical fixation showed better stress distribution compared with monocortical fixation in a linear finite element method analysis. 4) RBM pin implants are not recommended as transitional implants because they showed a lot of bone fracture in histologic specimens.

A tissue response to the titanium alloy (Ti-13Zr-6Nb) in vivo / 대한치과보철학회지

STATEMENT OF PROBLEM: Mechanisms of tissue-implant interaction and the effect of the implant surface on the behavior of cells has not yet been clarified. PURPOSE: This study was performed to investigate the tissue reaction to the titanium alloy submerged into rat peritoneum in vivo. MATERIALS AND METHODS: Titanium alloys (titanium-13Zirconium-6Niobium) were inserted inside the peritoneal cavity of Sprague Dawley rats. After 3 months, the tissue formed around the inserted titanium alloys were examined with a light-microscope. Tissue reaction around the material was analyzed by confocal microscopy to evaluate their biocompatibility in a living body. RESULTS: In in vivo study, foreign body type multinucleated giant cells were found in the fibrous tissue formed as a reaction to the foreign material (4 in 20 cases), but the inflammatory reaction was very weak. After experiment, the contaminants of biomaterials was removed from living tissue. In confocal microscopy, we observed that the staining of vinculin and actin showed mixed appearance. In a few cases, we found that the staining of vinculin and beta-catenin showed the prominent appearance. CONCLUSION: We found that titanium-13Zirconium-6Niobium alloy was an excellent biomaterial.

MARGINAL FITNESS AND MARGINAL LEAKAGE OF FIBER-REINFORCED COMPOSITE CROWNS DEPENDING UPON LUTING CEMENTS / 대한치과보철학회지

As Fiber-reinforced composite restorations cannot be made without leaving a marginal gap, luting cements play a pivotal role in sealing the margins as a prevention against margnal leakage. A recently introduced adhesive resin cement system is claimed to adhere chemically, as well as mechanically, to tooth substances, dental alloys and porcelain. But when considering the clinical variation, conventional cementation using Zinc Phosphate and Glass-Ionomer can be requested. A vitro study was undertaken to compare microleakage and marginal fitness of Fiberreinforced composite crowns(Targis/Vectris) depending upon luting cements. Fifty non-carious human premolar teeth were randomly divided into five experimental groups of 10 teeth each and luted with five luting cements.(Bistite II., Super-bond., Variolink II.), Zinc phosphate and Glass- Ionomer cement) After 24 hours of being luted, all specimens were thermocycled 300 times through water bath of 5degrees C and 55degrees C in each bath, then the quality of the marginal fitness was measured by the Digital Microscope and marginal leakage was characterized using Dye Penetration technique and the Digital Microscope The results were as follows : 1. The mean values of marginal fit were Bistite II(46.78micrometer), Variolink II(56.25micrometer), Super-Bond(56.78 micrometer), Glass-Ionomer(99.21micrometer), Zinc Phosphate(109.49micrometer) indicated a statistically significant difference at p<0.001. 2. The mean microleakage values of tooth-cement interface, restoration-cement interface were increased in the order of Variolink II, Bistite II, Super-Bond, Glass-Ionomer, Zinc Phosphate. 3. Crowns luted with resin cement (Bistite II, Super-Bond, Variolink II, etc) exhibited less marginal gap and marginal leakage than those luted with conventional Glass-Ionomer and Zinc Phosphate cement. 4. The results indicated that all five luting systems yielded comparable and acceptable marginal fit.

Finite element stress analysis on the supporting tissues depending upon the position of osseointegrated implants supporting fixed bridges / 대한치과보철학회지

No abstract available.