Titanium-zirconium alloy narrow-diameter implants for the rehabilitation of horizontally deficient mandibular posterior edentulous ridges / 대한치과보철학회지

In case of the insufficient horizontal bone loss, a regular diameter implant is not possible without lateral bone augmentation. In this situation, narrow diameter implants (NDIs) could be the alternative to lateral bone augmentation procedures. However, complication generally expected with the NDI is implant fracture. Recently, the survival rate and success rate of NDI in the posterior region are similar to that of standard-diameter implants (SDIs). These 3 case reports demonstrate the incorporation of NDI to replace missing mandibular posterior teeth. So far, the follow-up examination period was maintained and no unusual complications were presented for more than four years. Long term follow-up clinical data are needed to confirm the excellent clinical performance of these implants.

Clinical application of implant assisted removable partial denture to patient who underwent mandibular resection with oral cancer: A case report / 대한치과보철학회지

Mandible defects could be caused by congenital malformations, trauma, osteomyelitis, tumor resection. If large areas are included for reconstruction, those are primarily due to tumor resection defects. The large jaw defect results in a problem about mastication, swallowing, occlusion and phonetics, and poor esthetics causes a lot of inconvenience in daily life. It is almost impossible to be a part underwent mandibular resection completely reproduced, should be rebuilt artificially. This case is of a patient who was diagnosed with squamous cell carcinoma pT1N0M0, stage I in February 2004 and received surgery (combined mandibulectomy and neck dissection operation (COMMANDO) in oromaxillofacial surgery) in March 2004, by implant assisted removable partial denture. We could obtain good retention and stability through sufficient coverage and implant holding. Follow up period was about four years. Mandibular left third molar regions have been observed to have resorption of surrounding bone, and periodic check-ups are necessary conditions.

The non-linear FEM analysis of different connection lengths of internal connection abutment / 대한치과보철학회지

PURPOSE: This study is aimed to assess changes of stress distribution dependent on different connection lengths and placement of the fixture top relative to the ridge crest. MATERIALS AND METHODS: The internal-conical connection implant which has a hexagonal anti-rotation index was used for FEM analysis on stress distribution in accordance with connection length of fixture-abutment. Different connection lengths of 2.5 mm, 3.5 mm, and 4.5 mm were designed respectively with the top of the fixture flush with residual ridge crest level, or 2 mm above. Therefore, a total of 6 models were made for the FEM analysis. The load was 170 N and 30-degree tilted. RESULTS: In all cases, the maximum von Mises stress was located adjacent to the top portion of the fixture and ridge crest in the bone. The longer the connection length was, the lower the maximum von Mises stress was in the fixture, abutment, screw and bone. The reduction rate of the maximum von Mises stress depending on increased connection length was greater in the case of the fixture top at 2 mm above the ridge crest versus flush with the ridge crest. CONCLUSION: It was found that the longer the connection length, the lower the maximum von Mises stress appears. Furthermore, it will help prevent mechanical or biological complications of implants.

Morphometric analysis of maxillary alveolar regions for immediate implantation

PURPOSE: The purpose of this study was to provide an actual guideline in determining the shape, diameter, and position of the implant in immediate implantation by the measurement of the thickness of facial and palatal plate, the thickness of cortical bone on the facial and palatal plate, the diameter of the root, and the distance between the roots in the cadavers. MATERIALS AND METHODS: The horizontal sections of 20 maxillae were measured and analyzed to obtain the average values. Resin blocks were produced and cut serially at 1 mm intervals from the cervical line to the root apex. Images of each section were obtained and the following measurements were performed: The thickness of the facial and palatal residual bone at each root surface, the thickness of the facial and palatal cortical bone at the interdental region, the diameter of all roots of each section on the faciopalatal and mesiodistal diameter, and the interroot distance. Three specimens with measurements close to the average values were chosen and 3-dimensional images were reconstructed. RESULTS: The thickness of the facial and palatal cortical bone at the interdental region in the maxilla, the buccal cortical bone was thicker in the posterior region compared to the anterior region. The interroot distance of the alveolar bone thickness between the roots increased from anterior to posterior region and from coronal to apical in the maxilla. CONCLUSION: In this study, the limited results of the morphometric analysis of the alveolar ridge using the sections of maxilla in the cadavers may offer the useful information when planning and selecting optimal implant for immediate implantation in the maxilla.

Immediate implant placement into extraction sites with periapical lesions in the esthetic zone: a case report / 대한치과보철학회지

Esthetics is important in restoring maxillary anterior area. Alveolar bone resorption and loss of interdental papilla may be minimized by immediate implantation. Previous studies showed successful results with the immediate implantation in healthy extraction socket, while many of these studies objected the immediate implantation into extraction sites with periapical lesions. Recent studies, however, reported successful results of the immediate implantation into extraction sites with periapical lesions with careful debridement of extraction sockets and general medication of antibiotics prior to implantation. A 73-year-old female visited the department of Prosthodontics in oo University Dental Hospital with the chief complaint of fallen post-core and crown on left maxillary incisor. Although the incisor was with vertical root fracture and periapical lesion, the immediate implantation following the extraction of tooth was planned. Thorough socket debridement, irrigation with chlorhexidine, and tetracycline soaking were followed by immediate implantation. The general medication of antibiotics (Moxicle Tab.(R), 375 mg) was prescribed before and after the surgery. Immediate provisional restoration was delivered two days after the surgery, and the definitive metal-ceramic restoration was placed about six months later after reproducing the emergence profile from the provisional restoration. This case presents satisfying result esthetically and functionally upto two years after the placement of prosthesis with the harmonious gingival line and no loss of marginal bone.

Oral rehabilitation of a young adult with amelogenesis imperfect using metal-ceramic restoration: a clinical report / 대한치과보철학회지

Some patients with generalized attrition and teeth discoloration may want their anterior teeth to be treated just for esthetic improvement. Ameologenesis imperfecta, however, should be considered for such patients prior to any treatment with thorough clinical and radiographic examination. If a patient is diagnosed with amelogenesis imperfecta, the treatment on anterior teeth just for esthetic purpose is not advisable. In this case, a young man with amelogenesis imperfecta was treated with metal-ceramic restorations. The patient had generalized attrition, teeth discoloration, crown fracture, and cross-bite on the left teeth. The ultimate objective of this treatment was to enhance esthetics and masticatory function. The cross-bite on the left anterior teeth was treated with restorations, whereas the reverse horizontal overlap was maintained on the posterior. The patient was satisfied with the result esthetically and functionally, and the third month recall examination revealed no pathologic changes associated with the treatment.

Success rate and marginal bone loss of Osstem USII plus implants; Short term clinical study / 대한치과보철학회지

PURPOSE: The aim of this study was to evaluate the clinical value of Osstem(R) USII plus system implants. Clinical and radiographic data were analyzed for 88 implants placed and functionally loaded for a 12 month period at the Yonsei University Dental Hospital. MATERIALS AND METHOD: Based on the patient's medical records, clinical factors and their effects on implant marginal bone resorption, distribution and survival rate were analyzed. The marginal bone loss was evaluated at implant placement and during a 6 to 12 months functional loading period. The independent sample t-test was used to evaluate the interrelationship between the factors (alpha=0.05), and one way repeated measures ANOVA was used to compare the amount of marginal bone resorption. RESULTS: The cumulative survival rate for 88 implants was 100%. The marginal bone resorption from implant placement to prosthetic delivery was 0.24 mm and the average marginal bone resorption from prosthetic delivery to 12 months of functional loading was 0.19 mm. The total average bone resorption from implant placement to 12 months of functional loading was 0.43 mm. There were no statistically differences in the amount of marginal bone resorption when implants were placed in the maxilla or the mandible (P>.05), however, implants placed in the posterior areas showed significantly more marginal bone loss than those placed in the anterior areas (P<.05). CONCLUSION: Based on these results, the short term clinical success rate of RBM surface treated external connection domestic implants showed satisfactory results and the marginal bone loss was in accord with the success criteria of dental implants.

The effects of local factors on the survival of dental implants: A 19 year retrospective study / 대한치과보철학회지

PURPOSE: The aim of this retrospective study was to provide long-term data about the correlation between multifactorial local factors and the survival of implants. MATERIAL AND METHODS: During 19 years (1991 to 2009), 2796 implants were placed in 879 patients. From dental charts and radiographs, the following data were collected: patient's age at implant placement, gender, implant system, surface, length, diameter, location of implant placement, bone quality, primary stability, type of prosthesis. The correlations between these data and implant survival were analyzed. Statistical analysis was performed using Kaplan-Meier survival analysis, Chi-square test, odds ratio. RESULTS: 1. Among the 2796 implants, 150 implants failed that resulted in a cumulative survival rate of 94.64%. The cumulative survival rate of smooth surface implants (91.76%) was lower than rough surface implants (96.02%). 2. Anatomic location, implant surface, diameter of smooth surface implant, primary stability, type of prosthesis, patient's age and gender were significantly associated with implant survival (P < .05). 3. No significant difference in implant survival was found in relation to the following factors: implant length, bone quality, diameter of rough surface implants and type of rough surface according to implant manufacturer (P < .05). CONCLUSION: Local factors such as anatomic location, implant surface, diameter of smooth surface implant, primary stability and type of prosthesis have a significant effect on implant survival.

Impact of immediate and non-immediate provisionalization on the soft tissue esthetics of final restorations on immediately placed implants / 대한치과보철학회지

STATEMENT OF PROBLEM: Interpoximal papilla could be re-established without immeidate support with a provisional resotration following an immdiate implant placement. PURPOSE: Successful esthetic outcomes were reported utilizing immediate provisionalization following immediate implant placements. The aim of this study was to evaluate the soft tissue esthetics around immediately placed single tooth implant restorations with or without immediate provisional restorations. METHODS: A total of ten patients, who had a hopeless maxillary anterior tooth, were enrolled in this study. Screw retained provisional restorations were delivered to the randomly chosen 5 patients (immediate provisionalization group) on the day of immediate implant placement and maintained for about 5 months. For the remaining five patients (non-immediate provisionalization group), healing abutments were delivered on the day of surgery, replaced with screw retained provisional restorations approximately 3 months afterwards, and the provisional restorations were maintained for about 3 months. Digital photographs were taken at the delivery of final restorations in order to assess following variables; mesial papilla, distal papilla, soft tissue level, soft tissue contour and facial soft tissue prominence. The variables were compared to those of the contralateral natural tooth and scored by prosthodontists, periodontists, orthodontists and dental students. RESULTS: The immediate provisionalization group marked significantly higher scores on the following variables; soft tissue level and facial soft tissue prominence. In evaluating each variable, there were no notable differences in opinion between four dentist groups. CONCLUSION: Immediate provisionalization can be a treatment option to achieve superior soft tissue esthetics around immediately placed single implant restorations rather than non-immediate provisionalization approaches.

Oral health status and treatment need of institutionalized elderly patients / 대한치과보철학회지

STATEMENT OF PROBLEMS: In the area of dental care, the institutionalized elderly have placed the most vulnerable state, and we cannot find their subjective need of dental treatment because of the physical and mental disabilities, But we have no basic investigation of their oral health conditions. PURPOSE: The aims of the current study were to investigate the oral health status of institutionalized elderly patients who are in the least benefited side of dental service, and to analyze their dental treatment needs. MATERIAL AND METHODS: The survey of the oral status was carried out on 758 institutionalized elderly, and 212 elderly who was more than 65 years old from D dental office, and it was based on the Guidelines of Oral Health Research of year 2000 in Republic of Korea. RESULTS AND CONCLUSION: The DMFT index of the institutionalized elderly appeared higher than that of the same ages in control group, and it increased with age. The number of residual teeth of the institutionalized elderly appeared lower than that of the same ages in control group, and it decreased with age (p < .05). The number of fixed partial denture in institutionalized elderly was lower than that of the same ages in control group (p < .05). The percentage wearing removable partial denture was not significant between the elderly in institutions and the control group, and was not different according to age between the two groups. The percentage of institutionalized elderly wearing complete denture appeared lower than that of the same ages in control group, and it increased with age. The percentage of institutionalized elderly needing complete denture was higher than that of control group, and the percentage of elderly needing complete denture on the maxilla was higher than that of the mandible. 16.35% of the institutionalized elderly was living without denture in spite of their fully edentulous state. The need for complete denture increased rapidly with age. The number of valued teeth and dental prostheses in shortened dental arch concept and number of occluding pairs of teeth of institutionalized elderly were lower than that of the control group (p < .05). In institutionalized elderly, the number of residual teeth, the number of fixed partial dentures, and the percentage wearing removable partial dentures were higher in the mandible, and the percentage wearing complete dentures was higher in the maxilla (p < .05). The rate of institutionalized elderly needing prosthodontic treatment appeared to be 67.82%, where the number of occluding pairs of teeth was less than 10. When it is difficult to evaluate the subjective need of dental treatment as with the institutionalized elderly, estimation using the number of occluding pairs of teeth can be a useful indicator that can project treatment needs. For the oral health care of institutionalized elderly, it is essential to increase the awareness of nurses and caregivers who take care of them, about the importance of the oral health. Since the average life span and number of residual teeth are increasing gradually, the welfare policy should be changed to implementing regular dental examinations, preservative treatment forms and oral health control of dentulous patients where the traveling-treatment system and visit system are supplemented. And principles should be set that the present denture project of edentulous patients should be done by specialists who'll also be responsible for postmanagement. Through this research of institutionalized elderly, the oral health status which is worsened by aging could be confirmed. And the interest and positive participation of dental society on the elderly should come first in order to solve the rising treatment needs of the elderly patients.

The influence of collar design on peri-implant marginal bone tissue / 대한치과보철학회지

STATEMENT OF PROBLEM: Peri-implant marginal bone loss is an important factor that affects the success of implants in esthetics and function. Various efforts have been made to reduce this bone loss by improving implant design and surface texture. Previous studies have shown that early marginal bone loss is affected by implant neck designs. PURPOSE: The purpose of this study was to examine the influence of laser microtexturing of implant collar on peri-implant marginal bone loss. MATERIALS AND METHODS: Radiographical marginal bone loss was examined in patients treated with implant-supported fixed partial dentures. Marginal bone level was examined with 101 implant fixtures installed in 53 patients at three periods(at the time of implantation, prosthetic treatment and 6-month after loading). Four types of implants were examined. The differences of bone loss between implants(ITI standard) with enough biologic width and implants(ITI esthetic plus, Silhouette IC, Silhouette IC Laser-Lok(TM)) with insufficient biologic width have been compared. Resorption angles were examined at the time of prosthetic delivery and 6-month after loading. RESULTS AND CONCLUSION: Within the limitation of this study, the following results were drawn. 1. The marginal bone loss of ITI standard and Silhouette IC Laser-Lok(TM) was less than that of ITI esthetic plus and Silhouette IC(P0.05). There was no significant statistical difference between marginal bone loss of ITI esthetic plus and Silhouette IC(P>0.05). 2. There was no significant difference in marginal bone loss between maxilla and mandible(P>0.05). 3. There was no significant difference in resorption angle among four types of implants(P>0.05). The marginal bone of implants with supracrestal collar design of less than that of biologic width had resorbed more than those with sufficient collar length. The roughness and laser microtexturing of implant neck seem to affect these results. If an implant with collar length of biologic width, exposure of fixture is a possible complication especially in the anterior regions of dentition that demand high esthetics. Short smooth neck implant are often recommended in these areas which may lack the distance between microgap and the marginal bone level. In these cases, the preservation of marginal bone must be put into consideration. From the result of this study, it may be concluded that laser microtexturing of implant neck is helpful in the preservation of marginal bone.

Marginal tissue response to different Implant neck design / 대한치과보철학회지

STATEMENT OF PROBLEM: Loss of the marginal bone to the first thread have been accepted but continuous effort have been made to reduce this bone loss by varying implant design and surface texture. PURPOSE: This animal study has examined the histomorphometric variations between implants with micro-thread, micro-grooved and turned surfaced neck designs. MATERIAL AND METHODS: Four mongrel dogs have been used the premolars removed and left to heal for three months. One of each implant systems with turned neck, micro-thread and micro-grooved were placed according to the manufacturers' protocol and left submerged for 8 and 12 weeks. These were then harvested for histological examination. RESULTS: The histologically all samples were successfully ossointegrated and active bone remodelling adjacent to implants. With the micro-grooved implants 0.40 mm and 0.26 mm of the marginal bone level changes were observed at 8 and 12 weeks respectively. The micro-threaded implants had changes of 0.79 mm and 0.56 mm at 8 and 12 weeks respectably. The turned neck designed implants had marginal bone level changes of 1.61 mm and 1.63 mm in 8 and 12 weeks specimens. A complex soft tissue arrangement could be observed against micro-threaded and micro-grooved implant surfaces. CONCLUSION: Within the limitations of this study, it could be concluded that implants with micro-grooved had the least and the turned neck designed implants had the most changes in the marginal bone level. The textured implant surfaces affect soft tissue responses.

The influencing factors of periotest. value and implant stability quotient / 대한치과보철학회지

STATEMENT OF PROBLEM: Periotest. and OsstellTM were known as the most objective and quantitative mobility tests available for evaluating stability of implant in vivo. Although a correlation between PTV widely used and ISQ recently introduced exist, a PTV was corresponded to various ISQ. A correct evaluation of implant stability could be obtained only after one has a thorough understanding of the limitations of devices and factors that affect measurements. PURPOSE: The purpose of this study was to investigate the causes of variables in the values obtained with these two tests. MATERIAL AND METHOD: A total of 333 implants: 134 Bra.nemark, 5 Silhouette and 194 ITI implants were investigated. Result: 1. There was a correlation between PTV and ISQ (Spearman correlation =0.39, p<0.0001) 2. The factors that affected ISQ were diameter of implant fixture, location of implant and implant system (submerged type vs non-submerged type). 3. The factors that affected PTV were diameter of implant fixture, location of implant, and elapsed time after implant placement. 4. There was no significant difference between different surface treatments of RBM, smooth surface and ti-unite on PTV and ISQ. 5. In radiographic finding, no saucerization or bone resorption has been detected in implants with ISQ values that were above the average level of each PTV. These higher values had higher bone densities around the implant fixture. Saucerization was observed in the most impants with ISQ values that were below the average level of each PTV. CONCLUSION: There was a correlation between ISQ and PTV. However, each measuring methods had factors influencing the measured values. PTV were less sensitive to marginal bone resorption and influenced with the striking point on an implant to the level of bone. With ISQ, the height of implant from bone level to transducer should be considered.

The influencing factors of periotest. value and implant stability quotient / 대한치과보철학회지

STATEMENT OF PROBLEM: Periotest. and OsstellTM were known as the most objective and quantitative mobility tests available for evaluating stability of implant in vivo. Although a correlation between PTV widely used and ISQ recently introduced exist, a PTV was corresponded to various ISQ. A correct evaluation of implant stability could be obtained only after one has a thorough understanding of the limitations of devices and factors that affect measurements. PURPOSE: The purpose of this study was to investigate the causes of variables in the values obtained with these two tests. MATERIAL AND METHOD: A total of 333 implants: 134 Bra.nemark, 5 Silhouette and 194 ITI implants were investigated. Result: 1. There was a correlation between PTV and ISQ (Spearman correlation =0.39, p<0.0001) 2. The factors that affected ISQ were diameter of implant fixture, location of implant and implant system (submerged type vs non-submerged type). 3. The factors that affected PTV were diameter of implant fixture, location of implant, and elapsed time after implant placement. 4. There was no significant difference between different surface treatments of RBM, smooth surface and ti-unite on PTV and ISQ. 5. In radiographic finding, no saucerization or bone resorption has been detected in implants with ISQ values that were above the average level of each PTV. These higher values had higher bone densities around the implant fixture. Saucerization was observed in the most impants with ISQ values that were below the average level of each PTV. CONCLUSION: There was a correlation between ISQ and PTV. However, each measuring methods had factors influencing the measured values. PTV were less sensitive to marginal bone resorption and influenced with the striking point on an implant to the level of bone. With ISQ, the height of implant from bone level to transducer should be considered.

Comparison of maximum occlusal forces on osseointegrated implant supported fixed prostheses and natural teeth / 대한치과보철학회지

PURPOSE: The purpose of this study was to compare the maximum occlusal force implant prostheses to natural teeth. MATERIAL AND METHOD: Fifty nine patients treated either with Bra.nemark implants and ITI implants during the recent ten years were involved in this study. The maximum occlusal force were measured with unilateral bite force recorder and dental prescale system. RESULTS: 1. The maximum occlusal forces of the implant prostheses and natural teeth were not significantly different where measured with unilateral bite force recorder and dental prescale system. 2. The maximum occlusal forces were not significantly different between Bra.nemark implant and ITI implant prostheses. 3. The maximum occlusal forces of the implant prostheses had lower when compared with natural teeth during 1-6 months functional periods when measured with the unilareral bite force recorder(p<0.05) and 1-12 months functional periods when measured with the dental prescale system(p<0.05). After these periods there was not statistical significant difference between the implant prostheses and natural teeth. 4. The maximum occlusal forces of the wide diameter implant prostheses were higher than the maximum occlusal forces of the regular diameter implant prostheses when measured with dental prescale system(p<0.05), but there was no significant difference between the wide diameter and the regular diameter implant prostheses when measured with unilateral bite force recorder. 5. The maximum occlusal forces of the single implant prostheses were not significantly different with the splinting implants prostheses. 6. The maximum occlusal forces of the implant prostheses were not significantly different by age and sex. 7. There was significantly different between maximum occlusal forces measured with unilateral bite force recorder and dental prescale system(p<0.0001), but there was positive correlation(r=0.52, p<0.05). CONCLUSION: The maximum occlusal forces of the implant prostheses were not significantly different to natural teeth during clenching and unilateral maximum biting.

Longevity and failure analysis of fixed restorations serviced in Korea / 대한치과보철학회지

STATEMENT OF PROBLEM: Every effort has been continually made to obtain objectivity in measuring the longevity of fixed restorations, such as by establishing unified judgement standard for deciding success and adopting statistical method that analyzes the data of successful and failed cases at the same time. In Korea, however, desired level of development has not to be made in this field yet. PURPOSE: This study, adopting California Dental Association (CDA) quality evaluation system, established objective standard for deciding success, and inferred the longevity of fixed restorations and their failure analysis through adopting Kaplan-Meier survival analysis. Material and method. In order to assess the longevity of fixed restorations serviced in Korea and causes of failure, a total of 1109 individuals (aged 15-74, 716 women and 393 men loaded with 2551 unit fixed restorations, and 1934 abutments) who lived in Kyung-In Province were examined and the findings were as follows: RESULTS: 1. Length of service of fixed restorations serviced in Korea was 6.86+/-0.15 yr (mean), 5.5 yr (median), and the rate of success was 65.82% in 5 year survival, and 21.15% in 10 year survival. 2. When there was patient's need for replacing old prosthetics, longevity of fixed restorations was 7.51+/-0.27 yr (mean), 7 yr (median), and the rate of success was 61.08% in 5 year survival, and 17.57% in 10 year survival. 3. Longevity of fixed restorations was longest in the over-sixty age group(9.21+/- 0.66) and that of the teen age group(3.39+/-0.28) was shortest (p0.05). 9. Longevity of fixed restorations made of non precious metal was longest (9.60+/-0.40 yr), semi precious and precious trailing behind(p0.05). 11. Longevity of fixed restorations was longest in the centric interference group(9.35+/-0.62) (p<0.05) among different types of occlusal interference. CONCLUSION: We found that longevity of fixed restorations serviced in Korea is affected by age, gender and type of material, and that most frequent cause of failure is defective margin. In order to assess the accurate longevity of fixed restorations, unified research design, overcoming inter-observer difference and establishing the objective research items are needed. Furthermore, it is thought that prospective approach through thorough study and regular follow-ups is needed just from the start of research. Nationwide detailed studies on length of service of fixed restorations manufactured in Korea are hoped to be conducted hereafter.

Radiographic evaluation of the proximal bone level between two implants: A 3-year comparative study between Branemark and ITI implants in the mandibular posterior region / 대한치과보철학회지

STATEMENT OF PROBLEM: Branemark or ITI are two currently most widely used implant systems but with contrasting design, surgical and restoration methods. PURPOSE: The purpose of this study was to compare changes and its statistical significance in bone height and shape which may rise due to the differences between two implant systems. Also to analyse the effect of inter-implant distance on annual bone height changes. MATERIAL & METHOD: Those patients who were treated with two or more of either Branemark or ITI implants at posterior mandibular area at Yonsei University Dental Hospital, Implant Clinic were selected. At annual examination appointments, standardised radiographs using parallel technique were taken. Marginal bone and inter-implant crestal bone changes were measured and following results were obtained. RESULTS: 1) When ITI and Branemark system were compared, both annual marginal and inter-implant crestal bone height changes in ITI system in the first two years were smaller than Branemark and they were statistically significant. On the third year, however, there was no statistical difference between two implant systems on their annual bone level changes (p>0.05). 2) The Marginal and inter-implant crestal bone changes were compared when inter-implant distance was less than 4mm. Statistically significant bone level changes were noted on the first year only for ITI implants but in the first and second year for Branemark implants (p>0.05). 3) When comparing angulation changes between marginal bone and implant fixture, ITI system had smaller angulation changes but the annual changes were not statistically significant (p>0.05). CONCLUSION: Within the limitation of this study, it could be concluded that Branemark implant systems had more changes in marginal and inter-implant crestal bone level in the first and second year after loading with statistical significance. Further studies are recommended to see the effects of these bone loss during the first and second year after loading on the long term prognosis of Branemark Implants.

Cytocompatibility of thermally oxidized Ti-Ag alloys / 대한치과보철학회지

STATEMENT OF PROBLEM: In its preceding work, change in surface characteristics were investigated in consideration that both microtopograpy and macroscopic configuration of implants surface are two of the most important factors, in that they can construct agreeable environment by raising surface energy, to affect osseointegration and biocompatibility explained by cell proliferation. PURPOSE: This study focused on examining cytocompatibility of dental implants materials Ti-Ag alloys, of which mechanical and electrochemical superiority to cp-Ti or Ti6Al4V were verified, in comparison with that of cp-Ti, and Ti6Al4V. MATERIALS AND METHODS: In this regard, MTT tests for L-929, the fibroblast connective tissues and cell proliferation tests for osteoprogenitor cells, MC3T3-E1 were performed on cp-Ti, Ti6Al4V, and Ti-Ag alloys following thermal oxidation according to appropriate heat treatment temperature(untreated, 400, 600, 800degrees C) and heat treatment duration(untreated, 0.5, 1, 4 hr). RESULTS: The MTT tests on fibroblasts L-929 resulted in cell viability of over 90% in all experimental group entities, where, especially, the 100% of the viability for Ti-Ag alloys specimens accounted for the slightest adverse effect of ions release from those alloys on the cell. In MC3T3-E1 proliferation tests, the population of cells in the experimental group was roughly increased as experimentation proceeded, after two to four days. Proliferation showed highest viability for most of specimens, including Ti2.0Ag, treated at 600degrees C. CONCLUSION: In conclusion, it is the heat treatment temperature, not the duration that has considerable effects on thermal oxidation of specimens. Ti-Ag alloys treated at 600degrees C proved to have the best surface morphology as well as cytocompatibility when compared with Ti or Ti6Al4V for short-term biocompatibility tests.

Abrasion resistance of denture base resin including vinyloligosilsesquioxane / 대한치과보철학회지

STATEMENT OF PROBLEM: Recently, in attempts to reinforce the acrylic resin and to reduce the polymerization shrinkage, it has been reported that adding vinyloligo-silsesquioxane (vinyl-POSS) to PMMA significantly compensates for polymerization shrinkage and somewhat increases the fracture resistance. PURPOSE: There haven't been any studies on abrasion that can affect the adaptation of the denture in long-term use. In this study, abrasion resistance was compared between acrylic resin with vinyl-POSS and commercialized acrylic resin for denture base. In addition, the difference in abrasion resistance according to molding methods was compared. Material and method : Using PaladentR 20 including vinyl-POSS, PaladentR 20, Lucitone 199R, SR IvocapR, denture bases were fabricated using compression molding technique and continuous-pressure injection technique. Surface hardness and abrasion were measured for each group, and the worn surfaces were observed under a scanning electron microscope. RESULTS: 1. When surface hardness was measured for each material and molding technique, there was no statistically significant difference among the materials. (p<0.05) 2. When same denture base material and molding technique were used, the abrasion due to toothpaste solution was 5 times as severe as the abrasion due to soap solution. 3. When toothpaste solution was used, the abrasion decreased in the order of PaladentR 20, PaladentR 20 including vinyl-POSS, SR IvocapR, and Lucitone 199R. However, statistically significant difference was seen only among PaladentR 20, SR IvocapR, and Lucitone 199R.(p<0.05). 4. When soap solution was used, the abrasion was more severe in PaladentR 20 and including vinyl-POSS PaladentR 20 groups than in SR IvocapR and Lucitone 199R groups. (p<0.05). CONCLUSION: Addition of vinyl-POSS doesn't improve the abrasion resistance, and the abrasion resistance was similar to those of existing materials. Additional studies under different conditions are needed. For clinical application of vinyl-POSS, further investigations with different requirements and conditions are necessary.

The comparison between 2 wide implants and 3 regular implants in mandibular posterior area / 대한치주과학회지

Osseointegrated implants have been established as the standard treatment modality for full/partial edentulous patients since the 1960's, and the long term results for full edentulous patients have proven to be successful. Based on these results osseointegrated implants are now widely used for partial edentulous patients. There has been an increased interest towards the efficacy of wide implants, despite many reports mentioning the lower success rate of wide implants compared to regular implants. Recently, mandibular molar area defects are commonly restored using 2 wide implants, but it is not determined whether which treatment modality-3 regular implants or 2 wide implants-shows superior success rate. In this study, 2 wide implants and 3 regular implants used for the restoration of mandibular molar area are used to compare the survival rate of 1-4 years, and to analyze and compare the failure factors. The following conclusions could be drawn from this study. 1. Wide implants and regular implants showed 94.5% and 97,6% of survival rate respectively. After prosthodontic work, the survival rate was 100% and 98.1% for wide implants and regular implants respectively. 2. 5 failed implants have been removed. 2 wide implants and 1 regular implant have been removed due to failure of osseointegration, 1 wide implant was removed due to abscess formation caused by over-heating, and 1 regular implant was removed due to mechanical failure caused by over-loading within the first year of function. 3. No statistically significant difference was observed with respect to the amount of marginal bone loss of wide and regular implants.(P>0.05) In conclusion, restoration of the mandibular molar area using 3 regular implants was found to be a good treatment modality, and 2 wide implants could be considered a good treatment modality when success factors are taken into account.