Clinical features of the gingiva according to maxillary anterior teeth form in adult / 대한치주과학회지

It has been suggested that morphologic characteristics of the periodontium are partly related to the shape and form of the teeth. Furthermore, the severity of symptoms of periodontal disease have been proposed to differ among these various morphologic entities or "biotypes". The purpose of the present study was to examine the relationship between the form of the crowns in the maxillary anterior tooth segment and (1) a group of morphological characteristics and (2) the thickness of the gingiva. The thickness of gingiva was measured by ultrasonic device(SDM). 100 subjects devoid of symptoms of destructive periodontal disease were examined regarding, e.g., probing depth, gingival recession, width of keratinized gingiva, thickness of the keratinized gingiva. From maxillary study cast, the width(at the apical third-CW) and the length(CL) of the crowns of the 6 anterior teeth were determined. A CW/CL-ratio was calculated for each tooth and averaged for each tooth region. The individual mean CW/CL-ratio values for the central incisors were ranked. The 10 subjects ranked highest and the 10 ranked lowest were selected as having either a long-narrow(group N) or a short-wide(group W) form of the crown of the tooth. The data for each of the examined parameters were averaged for each tooth region in each subject and mean values for subjects in groups W and N were compared using the Student t-test. Stepwise multiple regression analysis, including data from the whole sample, was performed for each tooth region with the thickness of the free gingiva as the dependent variable. The results from the analyses demonstrated that individuals with a long-narrow form of the central incisors displayed, compared to individuals with a short-wide crown, form (1) a narrow zone of keratinized gingiva, (2) a pronounced "scalloped" contour of the gingival margin. There was no significant difference between groups N and W with respect to the thickness of the keratinized gingiva. The CW/CL-ratio data revealed that a certain form of the crowns in the central incisors was accompanied by a similar form in the lateral incisors and canine tooth region. The regression analyses demonstrated that the thickness of the keratinized gingiva in central, lateral incisors and canines was significantly related to the width of the keratinized gingiva.

The effect of third molar extraction on the periodontal status of the adjacent second molar / 대한치주과학회지

The aim of this study was to investigate the effect of third molar extraction on the periodontal status of the adjacent second molar. A total of 61 second molars in 31 adult periodontitis patients were examined. Among them, 27 second molars without adjacent third molars were included in the test group, and 34 second molars with third molar were included in the control group. Clinical parameters including plaque index, gingival index, and pocket depth and radiographic bone loss were measured around the second molar both in test and control group. The result showed that: (1) the mean plaque index and gingival index of control group were higher than these of the test group but the difference was not statistically significant, (2) the mean pocket depth of the control group was higher than the test group significantly at distal and buccal surface, (3) radiographic bone loss was greater in control group than test group significantly, (4) in Pearson correlation analysis between the age of extraction and radiographic bone loss in the test group, a positive relationship was shown(p<0.01). Within limitation of this study, it may be concluded that third molar extraction in periodontitis patients showed an improvement in periodontal status in contrast the patients group having third molar, therefore earlier a removal of third molar may minimize radiographic bone loss of the adjacent second molar.

Distribution, prevalence and sex linkage of molar root fusion / 대한치주과학회지

The objective of this study was to determine the incidence and distribution of root fusion as well as its sexlinkage in maxillary and mandibular molars. One hundred fifty patients who had eight maxillary and mandibular molars (third molars excluded) were consecutively selected for the study subjects. The subjects provided a total of 1200 molars, i.e., 600 maxillary and 600 mandibular molars. A decision about root fusion was made on the radiographic examination. If a molar had one root and/or roots fused at any part in the root surface, it was considered as having root fusion. The results showed that : (1) 14.1 % of the maxillary molars and 5.8 % of the mandibular molars had a fused root, (2) the prevalence of root fusion in the male was 33 % and 56.4 % in the female, (3) 60 % in the male and 48.8 % in the female had bilaterally paired root fusion, (4) the root fusion was most frequently observed in the maxillary second molar position, but none in the mandibular first position in this study. Within limitations of this study, it can be concluded that, in management of molars with a furcation problem, treatment options such as hemisection and root amputation should be chosen after careful evaluation of root fusion. Further studies are needed to investigate a possible relationship between root fusion and periodontal disease progression.

Expression of Osteoprotegerin and Osteoclast Differentiation Factor in Human Periodontal Ligament Fibroblast Cells / 대한치주과학회지

Recently, soluble TNF receptor homolog osteoprotegerin (OPG) and its membrane-bound ligand osteoclast differentiation factor (ODF) were found to regulate osteoclast formation and function, and bone metabolism. It is now well established that ODF acts via RANK expressed on hematopoietic osteoclast precursor cells to facilitate their differentiation to osteoclasts, and OPG prevents the formation of osteoclasts by interfering the binding of ODF and RANK. Expression of OPG and ODF was believed to be closely related to the pathogenesis of bone resorption and destruction from osteoporosis, periodontal diseases, malignant bone tumor, and arthritis. The periodontal ligament fibroblasts (PDLF), located between the tooth and tooth socket, has been thought to play an important role in maintaining bone homeostasis of periodontal tissues. However, the exact mechanism by which bone formation and resorption are regulated by PDLF is not well understood. In this study we have prepared primary cultures of human PDLF from periodontium of malaligned tooth extracted due to orthodontic reason, and determined steady state or inflammatory signal-induced OPG and ODF expression using RT-PCR and western blot analysis. OPG and ODF mRNA and protein were expressed constitutively in the PDLF and these expression were slightly increased by osteotropic cytokine IL-1beta. Lipopolysaccharide-treated PDLF showed decrease in OPG mRNA and protein expression, and increase in ODF mRNA and protein expression. These results indicated that PDLF influence the osteoclastogenesis by OPG and ODF expression in the inflammatory situation as well as physiological condition, and thereby pathogenesis of periodontal alveolar bone destruction.

A Study on the Loss of Tooth Substance and Surface Changes following Root Planing / 대한치주과학회지

The purpose of this study was to evaluate in vitro effects of the loss of tooth substance and root surface changes following root planing with various periodontal instruments. The 39 extracted human teeth due to severe periodontal disease were included. The total 50 root surfaces of 30 teeth were root planed with following instruments : Group 1, with Gracey curette, Group 2, with ultrasonic scaler, Group 3, with rotating root planing bur, Group 4, with Gracey curette plus rubber cup polishing, and Group 5, with ultrasonic scaler plus rubber cup polishing. Following root planing, the amount of tooth substance loss was evaluated by measuring the weight of the removed tooth substance and then 5 specimens (5x5x2mm) were randomly selected from the each group for roughness measurement. Root planed areas of each specimen were subjected to five measurements using the Profilometer and an average surface roughness values(Ra) for each group was obtained. Statistical difference for roughness values of each group was analyzed using oneway ANOVA and student t-test. For scanning electron microscopic(SEM) examination of root surface changes following root planing, 15 root surfaces of remaining 9 teeth were root planed and 3 specimens were randomly selected. The mean loss of tooth substance removed was Group 1, 7.0+/-1.09mg, Group 2, 1.3+/-1.00mg, Group 3, 5.8+/-1.72mg, Group 4, 8.7+/-1.34mg, and Group 5, 4.5+/-1.68mg following root palning, respectively. These results indicate that curette is effective instrument in the respect of diseased root substance removal. The average surface roughness values are following results : Group 1 and Group 4 were the smoothest surface (Ra=0.34+/-0.06micrometer, Ra=0.34+/-0.04micrometer, respectively) and Group 2 was the roughest surface (Ra=2.09+/-0.06micrometer). Statistical analysis of roughness values demonstrated a highly significant difference (P<0.05) between each experimental groups. However, no statistically significant difference in roughness values were observed between the Group 1 and Group 4. The results in this study suggest that curette and/or polishing procedure should be done after root planing with ultrasonic scaler and caution should be used with diamond-coated bur during routine root planing procedure.