Three-dimensional finite element analysis of unilateral mastication in malocclusion cases using cone-beam computed tomography and a motion capture system

PURPOSE: Stress distribution and mandible distortion during lateral movements are known to be closely linked to bruxism, dental implant placement, and temporomandibular joint disorder. The present study was performed to determine stress distribution and distortion patterns of the mandible during lateral movements in Class I, II, and III relationships. METHODS: Five Korean volunteers (one normal, two Class II, and two Class III occlusion cases) were selected. Finite element (FE) modeling was performed using information from cone-beam computed tomographic (CBCT) scans of the subjects' skulls, scanned images of dental casts, and incisor movement captured by an optical motion-capture system. RESULTS: In the Class I and II cases, maximum stress load occurred at the condyle of the balancing side, but, in the Class III cases, the maximum stress was loaded on the condyle of the working side. Maximum distortion was observed on the menton at the midline in every case, regardless of loading force. The distortion was greatest in Class III cases and smallest in Class II cases. CONCLUSIONS: The stress distribution along and accompanying distortion of a mandible seems to be affected by the anteroposterior position of the mandible. Additionally, 3-D modeling of the craniofacial skeleton using CBCT and an optical laser scanner and reproduction of mandibular movement by way of the optical motion-capture technique used in this study are reliable techniques for investigating the masticatory system.

Antiplaque and antigingivitis effects of a mouthrinse containing cetylpyridinium chloride, triclosan and dipotassium glycyrrhizinate

PURPOSE: The goal of this study was to evaluate the clinical anitplaque and antigingivitis effects of a mouthrinse containing cetylpyridinium chloride (CPC), triclosan and dipotassium glycyrrhizinate (DPZ) in patients with gingivitis and mild periodontitis. METHODS: Thirty-two subjects were randomized into 2 groups. The test group used a mouthrinse containing 0.05% CPC, 0.02% triclosan and 0.02% DPZ, while the control group used a placebo mouthrinse. At baseline, 2 weeks and 4 weeks, the papillary bleeding index (PBI), Turesky-Quigley-Hein plaque index (PI) and Loe-Silness gingival index (GI) were assessed. During the experimental period, the patients used the mouthrinse for 30 seconds, 4 to 5 times/day (10 mL/time) within 30 minutes after toothbrushing. RESULTS: No adverse effects appeared in either the experimental or the control group. Regarding PBI, PI and GI values, statistical significance was detected between values at baseline and 2 weeks for both groups (P<0.05). In the experimental group, statistically significantly lower values were detected at 4 weeks compared to at 2 weeks. However, in the control group, no statistically significant difference was detected between the values at 2 weeks and 4 weeks. Additionally, the mean value after 4 weeks for the control group was slightly higher than the mean value after 2 weeks for the control group. CONCLUSIONS: This study for 4 weeks demonstrated that mouthrinses containing CPC, triclosan and DPZ may contribute to the reduction of supragingival plaque and gingivitis.

Antiplaque and antigingivitis effects of a mouthrinse containing cetylpyridinium chloride, triclosan and dipotassium glycyrrhizinate

PURPOSE: The goal of this study was to evaluate the clinical anitplaque and antigingivitis effects of a mouthrinse containing cetylpyridinium chloride (CPC), triclosan and dipotassium glycyrrhizinate (DPZ) in patients with gingivitis and mild periodontitis. METHODS: Thirty-two subjects were randomized into 2 groups. The test group used a mouthrinse containing 0.05% CPC, 0.02% triclosan and 0.02% DPZ, while the control group used a placebo mouthrinse. At baseline, 2 weeks and 4 weeks, the papillary bleeding index (PBI), Turesky-Quigley-Hein plaque index (PI) and Loe-Silness gingival index (GI) were assessed. During the experimental period, the patients used the mouthrinse for 30 seconds, 4 to 5 times/day (10 mL/time) within 30 minutes after toothbrushing. RESULTS: No adverse effects appeared in either the experimental or the control group. Regarding PBI, PI and GI values, statistical significance was detected between values at baseline and 2 weeks for both groups (P<0.05). In the experimental group, statistically significantly lower values were detected at 4 weeks compared to at 2 weeks. However, in the control group, no statistically significant difference was detected between the values at 2 weeks and 4 weeks. Additionally, the mean value after 4 weeks for the control group was slightly higher than the mean value after 2 weeks for the control group. CONCLUSIONS: This study for 4 weeks demonstrated that mouthrinses containing CPC, triclosan and DPZ may contribute to the reduction of supragingival plaque and gingivitis.

A radiographical study on the changes in height of grafting materials after sinus lift: a comparison between two types of xenogenic materials

PURPOSE: The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase the needed vertical height to overcome this problem. However, grafting materials used for the sinus lift technique eventually show resorption. The present study radiographically compared and evaluated the changes in height of the grafting materials after carrying out maxillary sinus elevation with a window opening procedure. This study also evaluated the difference between two xenogenic bone materials when being used for the sinus lifting procedure. METHODS: Twenty-one patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with either bovine bone (Bio-Oss(R)) with platelet-rich plasma (PRP) or bovine bone (OCS-B(R))/PRP. A total of 69 implants were placed equally 6-8 months after the sinus lift. All sites were clinically and radiographically evaluated right after the implant surgery, 7-12 months, 13-24 months, and 25-48 months after their prosthetic loading. RESULTS: Changes of implant length/bone length with time showed a statistically significant decreasing tendency (P 0.05). In contrast, the OCS-B(R) group showed a significant decrease with time (P 0.05). CONCLUSIONS: The results showed that there was significant reduction in comparison with data right after placement, after 7 to 12 months, 13 to 24 months, and over 25 months; however, reduction rates between each period have shown to be without significance. No significant difference in height change was observed between the Bio-Oss(R) and the OCS-B(R) groups.

Histologic evaluation of low-intensity pulsed ultrasound effects on bone regeneration in sinus lift

PURPOSE: Many techniques have been described for achieving vertical augmentation of the maxillary sinus. The aim of this study is to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) to enhance bone regeneration after sinus floor elevation. METHODS: The sinus lifting technique was performed through a lateral approach on 8 different sites of 5 patients (3 males and 2 females) and their mean age was 45.7 years old. The sites were randomly assigned to the control or test groups. The control group had 4 sites that received lateral sinus lifting procedure only, while the test group had 4 sites that received LIPUS application after the lateral sinus lifting procedure. 24-32 weeks (an average of 29 weeks) postoperatively, new bone formation in the augmented sinus sites was evaluated through histologic and histomorphometric analyses of the biopsy specimens obtained during implant placement. RESULTS: In the test group, the mean percentage of newly formed bone was 19.0+/-2.8%. In the control group, the mean percentage of newly formed bone was 15.2+/-3.1%. The percentage of newly formed bone was approximately 4% higher in those cases where the sinus was treated by LIPUS than the percentage in those cases where it was not used. The difference was statistically significant. CONCLUSIONS: Within the scope of this study, low-intensity pulsed ultrasound application after sinus lifting appeared to have a significant effect on the development of new bone formation.

Comparison of implant survival rate by sinus lifting technique in implantation with sinus lift / 대한치주과학회지

PURPOSE: The purpose of this study was comparison of survival rate of implant as two sinus elevation techniques and when window opening procedure had done it was comparison of survival rate of implant between the procedure of implantation after 6 month of sinus elevation to allow healing period and that of implantation with sinus elevation simultaneously. MATERIAL AND METHODS: All 79 of patients treated at DanKook University Dental Hospital Dept. of Periodontics for 164 implantation of maxillary posterior edentulous area with sinus elevation. Sinus elevation technique was divided of the technique : Osteotome technique and window opening technique. RESULT: 14 implants among 96 implants was failed implants of using osteotome for sinus elevation whereas one implant of 68 implants was failed of using window opening technique. CONCLUSION: Window opening technique had higher survival rate than osteotome technique. In case of window opening, there was no significant difference of immediate implantation and delayed implantation.

A study on the biological characteristics of modified titanium surface / 대한치주과학회지

PURPOSE: The purpose of this research is to study about initial adhesion, proliferation and activation of osteoblast to titanium surface treated with machined, hydroxyapatite coating, resorbable blast material blasting and anodizing method. MATERIAL AND METHODS: After treating the titanium surface of each block with machined, impurities were removed and sterilized. The number of cells attached from cultured osteoblast of respective experimental groups were measured at 1, 4, 7, and 14day and alkaline phosphatase, calcium, and inorganic phosphate concentration of cultured solution was measured. RESULT: Anodizing group showed the highest rate of cell attachment and proliferation activity. RBM treated group showed the highest increasing on their alkaline phosphatase activity, on the calcium apposition, on inorganic phosphate apposition of 1 and 4 days in cultured osteoblast to compare with other groups. CONCLUSION: On the basis of these findings, we conclude that surface modification of titanium was profoundly effected on the attachment, proliferation and activation of osteoblast in initial stage osseointegration.

A compare research of machined implant and RBM surface implant / 대한치주과학회지

PURPOSE: To evaluate RBM surface implant which has its good character like that good initial stability, early bone formation. MATERIAL AND METHODS: In this study fixures have divided in 2 group: Machined(Group I), RBM(Group II). Total 10 fixtures were implanted on rabbit which sacrificed on week 2 and week 4 for the histological specimens. By these specimens polarized microscopic view, micro CT view, ISQ value were measured, compared and analysed by each group to figure out the evidence that clinical use of RBM implant. RESULT: ISQ value had no significance differences between 2 groups, However in each group 4, 8 weeks had higher ISQ value than 2 weeks. In polarized microscope, calcification level was following : Group II, Group I. In micro CT, formation of cancellous bone level was following : Group II, Group I. CONCLUSION: RBM implant was the most excellent on the early bone formation and good initial stability.

A comparative study for guided bone regeneration of silk fibroin nanomembrane(NanoGide-S(TM)) / 대한치주과학회지

PURPOSE: To evaluate the safety and efficiency of bone regenerative abilities of silk fibroin nanomembrane(Nanoguide-S) MATERIAL AND METHODS: The objects were 38 patients who had large defect at extraction sockets caused by chronic periodontitis and silk fibroin nano matrix were used on experimental group(N=19) and PLA/PLGA matrix were used on control group(N=19). The width, height, and length by crown-apical direction(socket depth) of defects were measured with the occlusal plane as a reference plane, and tooth axis direction, perpendicular to tooth axis direction were measured on radiographs at 3 months pre-operative, 3 months post-operative. RESULT: Tissue response to silk fibroin nano matrix and Biomesh were clinically satisfactory and complications such as swelling, exudation, ulceration and vesicles were not found except the ordinary discomfort of operated portion. 3 months later, the width, height, and length by crown-apical direction (socket depth) of defects were clinically improved in both groups with no significant difference. 3 months later radiolucency of tooth axis direction and perpendicular to tooth axis direction were all increased in both groups with no significant difference. CONCLUSION: By these results biodegradadable silk fibroin nano matrix was efficient in GBR on alveolar bone resorption caused by periodontitis compared to Biomesh.

A Comparison of Clinical Effect for Root Coverage / 대한치주과학회지

PURPOSE: The purpose of this study was to compare clinical effect of the Langer & Langer technique , the modified Langer & Langer technique and Bruno technique. MATERIAL AND METHODS: 30 patients who have gingiva recession(Miller class I or class II) were carried root coverage. Langer & Langer technique(14 patients/32 tooth), modified Langer & Langer technique(5 patients/10 tooth) and Bruno technique(11 patients/18 tooth) was carried. At baseline and average 3 months after operation, it was estimated clinical index(Pocket depth, gingiva recession, clinical attachment level, keratinized gingiva, scar tissue, root coverage rate) by Williams style probe. RESULT: Root coverage rate is indicated Langer & Langer technique(85%), Modified Langer & Langer technique(86%) and Bruno technique(90%). CONCLUSION: All three of the procedures were effective in gingival recession and improved clinical parameters.

The comparative study: the regenerative effect depends on size of bone graft material in bone loss site around dental implant / 대한치주과학회지

PURPOSE: The purpose of this study is to investigate on the regenerative capacity by using different size of graft materials around bony defect around implant. MATERIAL AND METHODS: Dental implant fixtures(Bio-TIS, Korea) were placed into the tibia of 8 rabbits. After placement of implant, artificial defects were created for each group, and the size of bone graft materials were used according to each designated group. 4 weeks after surgery, 8 rabbits were sacrificed. The histologic and histomorphometrical study were done for comparison of the regenerative capacity using 80-90micrometer and 200~1000micrometer size of grafting materials of OCS-B(R). RESULT: Matured bone formation was significantly increased more in Group E1(80-90micrometer) than in Group E2(200~1000micrometer). Group E1(80-90micrometer) showed more significant augmentation in marginal length of graft material per unit area than Group E2(200~1000micrometer). Group E1(80-90micrometer) showed more interspace in graft material than Group E2(200~1000micrometer). Control group showed no new bone formation around and inside of implanted fixture. CONCLUSION: Small grafting material size has great influence on bone regeneration.

EPMA analysis of bone formation around RBM surface implant / 대한치주과학회지

PURPOSE: To evaluate bone formation on the implant surface between machined fixture and RBM surface fixture through analyzing of distribution and concentration of Ca and P by EPMA. MATERIAL AND METHODS: Fixtures had divided in 2 group: Machined(Group I), RBM (Group II). Total 4 fixtures were implanted on rabbit which sacrificed on 2 week and 4 week for the histological specimens. By these specimens EPMA value were measured, compared and analysed by each group to figure out the evidence of clinical use of RBM implant. RESULT: After 2 weeks and 4 weeks , it was analyzed that bone formation area, distribution and concentration of Ca and P by EPMA. In distribution and concentration of P Group II was higher than Group I, but there were no statistical significances. In new bone formation area, Group II was more higher than Group I with statistically significances. Both of group, after 4 weeks area is little bit higher than after 2 weeks area but there is no statistically significances. CONCLUSION: RBM implant was better than machined implant on the early bone formation.

Comparison analysis of pain experienced by patients during periodontal examination using thinner versus thicker probes / 대한치주과학회지

During periodontal examination and periodontal recall visit, patients might feel pain. Probing with 0.45mm diameter probe, "overprobing" into connective tissue underlying periodontal pocket could be the primary aspect of pain. The purpose of present study, performed during recall visit, was to compare the levels of pain experienced by patients during periodontal probing using probes with the tip diameter of either 0.45mm or 0.63mm. Twenty patients were enrolled: 3 periodontists each exammined 20 patients at the Dankook university dental hospital. in each patient at six sites per tooth, diagonal maxillary/mandibular quadrants were probed with 0.45mm diameter and 0.63mm diameter probe. Lower pain responses following probing with the 0.63mm diameter probe as compared to the 0.45mm probe were observed for patients of therapist 2 and the upper VAS quartile Groups(P<0.05). For therapist 1 and 3 groups, no differences were found. Patient worry about the pain while dental treatment procedures. If therapist use 0.63mm diameter probe while periodontal examination and recall visit, the patient's pain and discomfort could be reduced. Therefore, patient will cooperate more during the treatment, which leads to a better result. Dental therapists should make an effort to minimize the degree of discomfort during treatment. Dental therapist periodically should evaluate this part of their skill by asking patients and promote this skill.

The comparison clinical study effect of Diode Laser & Ms coat usage for dentinal hypersensitivity following Periodontal therapy / 대한치주과학회지

The purpose of this study was to evaluate the effect of diode laser & desensitizing agents to overcome hypersensitizing root surfaces problem after periodontal treatment. 20 patients(60 teeth) presented were volunteered in this study. Diode laser & MS coat was respectively applied on hypersensitizing root surfaces after periodontal treatments. Following application, they were evaluated immediately. The results were as follows: 1. The frequency and degree of root surface hypersensitivity levels were measured by the sequence of tactile and air stream. 2. Reduction of root surfaces hypersensitivity by tactile were for Diode laser and Ms coat application respectively 3.0294+/-2.0224 and 3.2692+/-1.6139. 3. Reduction of root surfaces hypersensitivity by air stream were for Diode laser and Ms coat application respectively 3.0294+/-2.0224 and 3.2692+/-1.6139. 4. It could be said that Diode Laser and Ms coat application were significantly effective in reducing dentin hypersensitivity as far as concerned effect, Ms coat applicatio showed more effective than Diode laser. In conclusion, both methods were significantly effective in reducing dentinal hypersensitivity. Therefore, it was recommended that Diode laser and desensitizing agents could be used routinely for patients dentinal hypersensitivity following periodontal treatment.

A comparative study of the clinical effects of Fibrin adhesive and Calcium sulfate barrier in the treatment of mandibular class II furcations using Xenograft / 대한치주과학회지

Periodontal regeneration refers to the restoration of bone, cementum and periodontal ligament to their original levels before damage from periodontal disease process. Various surgical techniques to the promotion of periodontal regeneration have been used. Bone graft and guided tissue regeneration have used for the regeneration of furcation involvements which caused by periodontal disease. Fibrin adhesive is agents that have been shown to be effective in periodontal regeneration and biological carrier. Calcium sulfate which is one of the resorbable barrier materials has used for guided tissue regeneration. The purpose of this study was to compare the clinical effects between bone graft using fibrin adhesive and calcium sulfate barrier in the mandibular class II furcation involvement. For the study, twenty-six class II furcation involved teeth were surgically treated. 13 furcation defects(test group) were treated with bonegraft and fibrin adhesive and the others(control group) were treated with bone graft and calcium sulfate barrier. Pocket depth, clinical attachment level and gingival recession were measured at baseline, postoperative 3 and 6 months. The results of the study are as follows: 1. The change of pocket depth and clinical attachment level in both groups was decreased significantly at 3, 6 months than at baseline(p<0.05). 2. The change of gingival recession in both groups was increased significantly at 3, 6 months than at baseline(p<0.05). 3. The change of pocket depth and clinical attachment level in both groups was decreased at 3, 6 months, and the change of gingival recession in both groups was increased at 3, 6 months but there were no statistically or clinically significant differences with both groups. 4. The significant reduction of the pocket depth and clinical attachment level exhibited marked changes at 3 months in both groups. In conclusion, the results of this study suggest that there are no statistically or clinically significant differences between fibrin adhesive and calcium sulfate barrier in the treatment of class II furcations using xenograft.

Study on the stress distribution depending on the bone type and implant abutment connection by finite element analysis / 대한치주과학회지

Oral implants must fulfill certain criteria arising from special demands of function, which include biocompatibility, adequate mechanical strength, optimum soft and hard tissue integration, and transmission of functional forces to bone within physiological limits. And one of the critical elements influencing the long-term uncompromise functioning of oral implants is load distribution at the implant-bone interface. Factors that affect the load transfer at the bone-implant interface include the type of loading, material properties of the implant and prosthesis, implant geometry, surface structure, quality and quantity of the surrounding bone, and nature of the bone-implant interface. To understand the biomechanical behavior of dental implants, validation of stress and strain measurements is required. The finite element analysis (FEA) has been applied to the dental implant field to predict stress distribution patterns in the implant-bone interface by comparison of various implant designs. This method offers the advantage of solving complex structural problems by dividing them into smaller and simpler interrelated sections by using mathematical techniques. The purpose of this study was to evaluate the stresses induced around the implants in bone using FEA. A 3D FEA computer software (SOLIDWORKS 2004, DASSO SYSTEM, France) was used for the analysis of clinical simulations. Two types (external and internal) of implants of 4.1 mm diameter, 12.0 mm length were buried in 4 types of bone modeled. Vertical and oblique forces of 100N were applied on the center of the abutment, and the values of von Mises equivalent stress at the implant-bone interface were computed. The results showed that von Mises stresses at the marginal bone were higher under oblique load than under vertical load, and the stresses were higher at the lingual marginal bone than at the buccal marginal bone under oblique load. Under vertical and oblique load, the stress in type I, II, III bone was found to be the highest at the marginal bone and the lowest at the bone around apical portions of implant. Higher stresses occurred at the top of the crestal region and lower stresses occurred near the tip of the implant with greater thickness of the cortical shell while high stresses surrounded the fixture apex for type IV. The stresses in the crestal region were higher in Model 2 than in Model 1, the stresses near the tip of the implant were higher in Model 1 than Model 2, and Model 2 showed more effective stress distribution than Model 1.

Radiographic evaluation of alveolar bone profile of maxillary anterior teeth in Korean young adult / 대한치주과학회지

In order to achieve a satisfactory esthetic result of periodontal surgery or implant in maxillary anterior area, periodontists must be aware of normal alveolar bone anatomy. The purpose of this study was to evaluate the relationship of alveolar bone morphology to tooth shape and form. 78(mean age : 25 yrs) periodontally healthy volunteers participated in this study. Two maxillary central incisor and one lateral incisor were selected to study. With minimal local anesthesia, guttapercha cone inserted to labial gingival sulcus of selected teeth just after bone sounding with periodontal probe. Metal ball (4mm diameter) attached to palatal fossa of central incisor. Then, periapical radiograph was taken according to long cone paralleling technique. After film scan, labial alveolar bone profile reproduced along interproximal bone and apical ends of gutta-percha cones on computer screen. By utilizing computer program, the distance from height of interproximal bone to the labial bone crest in central incisor-central incisor and central incisor-lateral incisor area was measured and converted to real distance by using vertical length of metal ball on film. After measuring crown length & width of central incisor, the 10 individuals ranked lowest CW/L ratio (crown width/length ratio) and the 10 ranked highest were selected as having a long-narrow(group N), or a short-wide(group W) form of the central incisors. Means of the distance from height of interproximal bone to the labial bone crest of group N, W were calculated and compared by means of independent t-test. The results were as follows: 1. Mean distance from the height of the interproximal bone to the labial bone crest was 3.5+/-0.7mm between two central incisor, and 2.8+/-0.6mm between central and lateral incisor. 2. Mean CW/L ratio of group N was 0.57, and group W was 0.8. Mean distance from the height of the interproximal bone to the labial bone crest of group N was higher than group W in both measured area(measurements of group N, W were 3.9+/-0.2mm and 3.5+/-0.2mm between two central incisor, 3.0+/-0.2mm and 2.8+/-0.2mm between central and lateral incisor), but there were no statistically significant differences when the groups were compared. Within the limits of the present study, there was a tendency that subjects with long-narrow teeth have more scalloped alveolar bone profile than subjects with short-wide teeth in upper anterior area, but no statistically significant differences were found.

Study on the stress distribution around two types of implants with an internal connection by finite element analysis / 대한치주과학회지

Adequate bone quality and stress distribution to the bone are of decisive importance for implant success. Even though the success rates of dental implants have been high, implant failures do occur. Overloading has been identified as a primary factor behind dental implant failure. The purpose of this study was to theoretically investigate the effect of two types of implants on the stress distribution in poor bone quality. Employing the finite element method, the study modeled a 4.1 mm diameter, 12.0 mm length implant placed in cortical or spongeous bone. A static loading of 100N was applied at the occlusal surface at 0, 30 degrees angle to the vertical axis of the implant. von Mises stresses concentrations in the supporting bone were analyzed with finite element analysis program. The results were as follows; 1. The stresses at the marginal bone were higher under buccal oblique load(30 degrees off of the long axis) than under vertical load. 2. Under buccal oblique load, the stresses were higher at the lingual marginal bone than at the buccal marginal bone, and the differences were almost the same. 3. Under vertical and oblique load, the stress was the highest at the marginal bone and lowest at the bone around apical portions of implant in cortical bone. 4. Under vertical load, Model 1 showed more effective stress distribution than Model 2 irrespective of bone types. On the other hand, Model 2 showed lower stress concentration than Model 1 under buccal oblique load.

A study on the periodontal status of second molar adjacent third molar / 대한치주과학회지

The purpose of this study was to determine the relationship between the third molar and periodontal status of the adjacent second molar. Fifty patients who had four maxillary and mandibular second molars were consecutively selected for the study subjects. The subjects provided a total of 200 molars, i.e., 100 maxillary and 100 mandibular molars, and classified the groups as follows; third molars that are normally erupted are control group, that are impacted are test 1 group, that are simply extracted are test 2 group, that are surgically extracted are test 3 group. Probing depth, plaque index, gingival index and mobility were measured. The results were as follows. 1. In mesial probing depth, there was no significantly difference. In distal probing depth, there was a significantly difference between control group and test 1 & 3 group in maxilla and between control & test 2 group and test 1& 3 group in mandible(p<0.05). 2. In buccal probing depth, there was a significantly difference between test 2 group and test 3 group in mandible. In lingual probing depth, there was a significantly difference between control group and test 1 & 3 group in mandible(p<0.05). 3. In plaque index, there was a significantly difference between test 1 group and test 2 group in maxilla, between test 1 group and control & test 2 group in mandible(p<0.05). 4. In gingival index, there was a significantly difference between control group and test 1 & 3 group in mandible. In mobility, there was no significantly difference(p<0.05). As a result of this study, the second molars adjacent to the third molars that are impacted or surgically extracted had poor prognosis, so impacted third molars should be extracted in early time and the second molars are actively treated for periodontal health.

A study of distribution, prevalence and relationship of the localized periodontitis of first and second molar root fusion / 대한치주과학회지

The purpose of this study was to determine the distribution, prevalence and relationship of the localized periodontitis of root fusion in maxillary and mandibular molars. One hundred patients who had eight maxillary and mandibular molars(third molars excluded) were consecutively selected for the study subjects. The subjects provided a total of 800 molars, i.e., 400 maxillary and 400 mandibular molars. A decision about root fusion was made on the radiographic examination. Probing depth, plaque index, gingival index and mobility were measured. The results were as follows. 1. 15.9% of the molars had a fused root. 22% of the maxillary molars and 9.8% of the mandibular molars had a fused molars. 2. In maxillary molars, the results of probing depth, plaque index, gingival index, mobility are more higher in test group than in control group, and there was a significantly difference except plaque index of maxillary first molars group(p<0.01). 3. In mandibular molars, the results of probing depth, plaque index, gingival index, mobility are more higher in test group than in control group, and there was a significantly difference(p<0.01). As a result of this study, it can be concluded that, in management of molars with a root fusion, we should detect the molars through the precise radiographic examination, early periodontal treatment and systematic treatment plan should be chosen. And postoperative continuing supportive periodontal therapy is needed.