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PubMed1985

Linear variation of the root surface area of the maxillary first molar.

The variation of root surface area (RSA) in 1-mm increments from the cementoenamel junction (CEJ) to the apex was determined for the maxillary first molar. Twenty extracted maxillary first molars were cross sectioned every millimeter, and each section was photographed, projected and measured with a calibrated opisometer. The RSA and percentage of RSA were calculated for each 1-mm section. The location of furcation entrances, root separations and roofs of the furcations was also determined. Analysis of the mean measurements demonstrated that (1) the largest per cent of RSAs were found in the furcation area; (2) the mean distance from the CEJ was 3.6 mm for the mesial furcation entrance, 4.2 mm for the facial furcation entrance and 4.8 mm for the distal furcation entrance; (3) the mean distance from the CEJ to the point at which the roots separate from the root trunk was 5.0 mm for the mesiobuccal root and 5.5 mm for the distobuccal root; (4) in 11 of the 20 teeth the roof of the furcation was coronal to all root separations, forming a concave dome between roots. According to the individual and mean measurements, horizontal attachment loss of 6.0 mm or greater would have resulted in Grade III furcation involvement in all the teeth studied.

Dental Cementum↗
PubMed1985

Root surface measurements of the mandibular first molar.

The root surface area (RSA) per millimeter of root length was determined for 20 extracted mandibular first molars. The molars were cross-sectioned at 1-mm increments, and each section photographed, projected and measured with a calibrated opisometer. The RSA and per cent RSA were calculated for each 1 mm of root length (1-mm section), the root trunk and the individual roots. Also measured was the location of the root separations from the root trunk, the location of the first detectable root concavity, and the prevalence of "intermediate bifurcation ridges" (IBRs). Mean measurements indicated that the greatest RSA per millimeter of root length was 4 to 7 mm apical to the cementoenamel junction (CEJ) in the area of the furcation. Of the total RSA, 48.7% was located in the coronal 6 mm of a root (mean length, 14.4 mm). Root separation occurred 4.0 mm apical to the CEJ with no tooth having a root trunk longer than 6 mm. Buccal and lingual root concavities were first present 0.7 mm and 0.3 mm apical to the CEJ, respectively. Fourteen (70%) of the 20 teeth had IBRs. According to the mean measurements, the mesial root was larger than the distal root by a ratio of 1.0:0.88. Horizontal attachment loss of 6 mm affecting both the buccal and lingual surfaces of the mandibular first molar would have resulted in a through and through (grade 3) furcation involvement of all the teeth studied.

Humans↗
PubMed1990

A computer-aided image analysis system for area measurement of tooth root surfaces.

The characteristics of a computer-aided Image Analysis System (IAS) to conduct linear and area measurements on tooth root surfaces were investigated. The borders of the features to be measured were extracted from a digitized video image by histogram-based thresholding and binarization. The lengths and square areas were expressed in the number of pixels. The reference-length and area of one pixel were obtained through measurement of the diameter of a metal ball of known diameter in the same digital image. The validity of the IAS was tested using radiographs of teeth containing round metal restorations of known diameter and area. The accuracy of the length measurements ranged from -2.0 to 2.1%, whereas the accuracy of area measurement was between -5.3 and 0.8%. The precision of the IAS to identify the borders of a tooth root surface and to reproducibly calculate its area, expressed in a coefficient of variation, ranges from 0.49 to 4.11%. The results indicate that imaging techniques can be applied to obtain very accurate measurements of tooth root surfaces.

Dental Enamel↗
PubMed1990

A quantitative study of cementum removal with hand curettes.

An in vitro study was conducted to quantitatively measure the depth of root surface removal using curettes of standardized sharpness and with definite stroke number. Extracted periodontally healthy teeth from patients 10 to 15, 16 to 25, and 26 to 40 years old had periodontal ligament remnants removed with dry gauze before being secured in a vertical position during root planing. The force applied to the root surface was measured with a tension load cell. The "bright line" test was used to assess curette sharpness. After histologic processing, the thickness of cementum adjacent to the root defect, the cementum (if any) in the root defect, total amount of cementum removed, and depth of root defect were measured by a microscopic ocular grid. Teeth from each age range were evenly distributed into 6 groups of 10 teeth each. In the majority of teeth from the 20 stroke group through the 70 stroke group, complete cementum removal was observed at the site of planing. However, in some sections from each group, fragments of cementum remained on the root surface. A positive relationship (r/s = 1) was found between the number of strokes and the force applied to the root surface and the mean depth of defect (P less than 0.05). However, an inverse relationship existed between mean force per stroke and mean defect depth (r/s = -.99) such that as mean force per stroke increased, the mean defect depth decreased. As the root surface became smoother with an increasing number of strokes, the forces increased and were more consistent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Periodontal implications of furcation entrance dimensions in Chinese first permanent molars.

Narrow dimensions of the entrance to furcations of multi-rooted teeth can complicate the periodontal management of furcation involvements. The objectives of this study were to measure the furcation entrance dimensions of first permanent molars from Hong Kong Chinese, and to compare these dimensions with those of the blade widths of periodontal instruments generally advocated for root surface instrumentation. A total of 363 first permanent molars, of which 185 were maxillary, were examined under 1.5 x magnification. Furcation entrance dimensions were measured using calibrated test gauges ranging from 0.3 mm to 1.5 mm. Furcation entrance dimensions equal to or less than 0.75 mm (the blade width of a new Gracey curet being 0.76 mm) in maxillary first molars were found in 79% of buccal entrances, 39% of mesial entrances, and 43% of distal entrances. In mandibular first molars, entrance dimensions equal to or less than 0.75 mm were encountered in 36% and 47% of buccal and lingual furcation entrances respectively. One-half of all furcation entrance dimensions of these first molars were less than the blade width of new Gracey curets. This high prevalence of narrow furcation entrances should be considered in the periodontal management of furcation involvement of first molars in Chinese.

Asian People↗
PubMed1992

Tooth morphology following root resection procedures in maxillary first molars.

The Disto-Buccal root is the most commonly resected root in maxillary molars. This root resection procedure results in a unique environment dictated by the contours of the remaining roots and the residual furcation between them. Tooth morphology was evaluated in 50 extracted maxillary first molars after disto-buccal root resection. The following measurements were studied: 1) The maximum concavity (D) on the distal aspect of the resected molar; 2) the minimum mesio-distal dimension (d) of tooth structure between the two remaining roots; 3) the width (s) of the residual interradicular septum; and 4) the distance (p) from the pulp chamber floor to the root separation on the distal aspect of the resected molar. The mean measurements were (D) = 2.47 mm, (d) = 3.67 mm, (s) = 3.33 mm and (p) = 2.70 mm. The value of (p) was equal to or less than 3 mm in 86% of the teeth; this means that the distance from the finish line to the interradicular osseous peak is less than 2.04 mm (average biologic width), if the finish line is placed on solid tooth structure about 1 mm below the pulp floor. Six percent of the resected molars had an overall topography easily amenable to periodontal maintenance and restorative procedures with (D) less than 2 mm, (d) greater than 3 mm, (s) greater than 3 mm, and (p) greater than 3 mm. Poor root anatomy of the remaining roots after removal of the disto-buccal root in maxillary first molars may be considered as a contraindication for root resection procedures. Unfortunately, this poor topography can be ascertained only during the surgery and after removal of the disto-buccal root.

Dental Pulp Cavity↗
PubMed1996

Clinical significance of furcation anatomy of the maxillary first premolar: a biometric study on extracted teeth.

Multirooted teeth in which chronic periodontitis has progressed to involve the furcation present special problems in treatment. The apical placement of furcation, narrow furcation entrance, concavities on the root surface, and the undesirable root configuration make instrumentation and plaque control difficult. Furcation involvement, when present in maxillary first premolars in particular, presents a poor prognosis as the furcation opens mesiodistally. This study on 100 extracted maxillary first premolars is an attempt to determine the frequency of bifurcation, the proximity of bifurcation to cemento-enamel junction, the depth of concavities on the root trunk and the furcal aspect of root, the diameter of furcation entrance, and the extent of root divergence.

Bicuspid↗
PubMed1998

Three-dimensional alveolar bone morphology analysis using computed tomography.

The purpose of the present study was to determine whether the use of 3-dimensional computed tomography (3DCT) is an effective method of imaging bone defect morphology caused by periodontal disease. A total of 186 sites from 9 patients were examined. Periodontal parameters were recorded after initial therapy. For the evaluation of bone resorption and root morphology, computed tomography (CT) scanning was performed and then CT images were reconstructed for 3-dimensional evaluation. Immediately prior to the surgery, bone sounding measurements were done under local anesthesia. The denuded bone measurement during periodontal surgery represented the true bone level. To compare the bone level obtained from 3DCT images with the true bone level, the examiner, without being informed of the patient's condition, traced the cemento-enamel junction (CEJ) and apical extent of the bone levels on the images of 3DCT, and measured the vertical distance between the CEJ and bone. The mean difference between 3DCT and the true bone level was 0.41+/-2.53 mm (mean+/-SD). The correlation between them showed a highly significant linear regression (R=0.75). However, the mean difference between the bone sounding level and the true bone level was 0.22+/-1.49 mm (R=0.91). Thus, bone sounding was slightly more accurate than 3DCT, but there was no significant difference between these two assessments (P >0.05). The results of present study indicate that 3DCT has the potential to allow precise assessment of bone defect caused by periodontal disease.

Adult↗
PubMed1998

Radiographic and clinical responses to periodontal therapy.

Mechanical periodontal therapy is widely used for a variety of periodontal conditions. While the clinical efficacy of this treatment has been validated, the radiographic response has not been studied in depth. The purpose of the present study was to examine the clinical and radiographic response to mechanical periodontal therapy, and assess the factors associated with these changes. One hundred and eight patients, with established periodontitis, received oral hygiene instruction and mechanical periodontal therapy for a period of 4 to 5 weeks. Scheduled maintenance visits were performed at 3, 6, 9, and 15 months. Probing depth (PD) and attachment level (AL) measurements were performed at baseline, and at 3 and 15 months. Intraoral radiographs were taken at baseline and 12 to 15 months postsurgery using a Rinn alignment system. Alveolar crestal height (ACH) measurements were performed on a pair of digitized images of the previously taken radiographs. An overall mean of patients' changes for PD, AL, and ACH was initially computed. Active sites (gainers and losers) were determined using a threshold method, and expressed as patient's percentage of active sites (number of active sites of the total sites measured in each patient). Mean overall probing reduction and AL gain was 0.5 mm and 0.44 mm, respectively. Of all sites measured, 16.6% exhibited AL gain, while only 6.2% of all sites exhibited AL loss. Mean overall change in ACH was -0.07 mm, of which 11.8% of all sites exhibited ACH gain, while 15.1% exhibited loss beyond the threshold. Non-smokers presented no change in bone loss, while smokers continued to lose bone at an annual rate of 0.17 mm, despite treatment (P <0.005). Likewise, the average percent of sites per patients showing attachment gain beyond the threshold were much greater in non-smokers (13.9%) compared to 9.0% in smokers (P <0.01). Mean probing reduction was 50% greater among non-smokers (0.6 mm) when compared to smokers (0.4 mm), which was also statistically significant (P <0.05). A positive and significant correlation was established between the percentage of sites with AL gain and sites with ACH gain (Rho =0.40; P=0.0001). It is suggested that monitoring sites for AL and ACH gain expressed as changes beyond a selective threshold is an important outcome variable in treatment studies.

Adult↗
PubMed2000

The deceptive nature of root coverage results.

BACKGROUND: The purposes of this article are to: 1) propose a new method of reporting root coverage data; 2) compare existing root coverage techniques using the proposed data analysis method; and 3) discuss additional refinements to root coverage data analysis. Past studies have equated percent defect coverage with root coverage. This gives deceptive information about the magnitude of the residual recession defect. Defect coverage of 67% could actually amount to 92% root coverage. METHODS: The use of mean root lengths will permit the determination of true root coverage data. This should be reported in addition to defect coverage data. Also including frequency data will provide a better assessment of the predictability of the surgical techniques. RESULTS: A comparison table of root coverage studies demonstrates that the connective tissue graft is the most effective and predictable method that has been tested. CONCLUSIONS: Further refinements to data analysis may help researchers identify the determinants of predictable root coverage.

Connective Tissue↗
PubMed2002

Root surface area of the mandibular cuspid and bicuspids.

BACKGROUND: The purpose of this study was to determine the total root surface area of extracted teeth by computerized image analysis and the amount of remaining attachment area assuming various amounts of bone loss due to periodontal disease. METHODS: One hundred fifty extracted mandibular teeth were evaluated, and measured from cusp tip to the cemento-enamel junction (CEJ), CEJ to root apex, and cusp tip to root apex. The fulcrum point of the tooth was also measured, along with the total root surface area of attachment and total surface area of attachment remaining following simulation of attachment loss in 2 mm increments. Measurements were made on 80 teeth on one proximal surface and either the buccal or lingual surface and multiplied by a factor of 2. Measurements on 70 teeth were made on all 4 root surfaces to predict the accuracy of measuring only 2 surfaces to determine root surface area. Images of the tooth surfaces were obtained by video camera and converted to computer image with measurement of the surface areas. RESULTS: The total root surface area for the mandibular cuspids and first and second bicuspids was 275.88 mm2, 251.45 mm2, and 271.81 mm2, respectively. The 2-sided and 4-sided measurements for the mandibular first bicuspid were 252.55 mm2 and 247.02 mm2, respectively (P>0.05). CONCLUSIONS: This study found the total root surface area to be greater than that in most previous studies. Increasing attachment loss is related to decreasing root surface area; however, this relationship is not directly proportional. No statistical difference was found between measuring 4 surfaces versus only 2 surfaces.

Alveolar Bone Loss↗
PubMed2004

Morphometric analysis of the furcation anatomy of mandibular molars.

BACKGROUND: Successful treatment of molar furcation defects remains a challenge in clinical practice. Knowledge of anatomic factors facilitates predictable management of furcation involvement lesions. The degree of success in managing furcation involvement is inversely related to the horizontal probing depth. The depth of the horizontal component of attachment loss can vary depending on the external tooth-surface reference points used. However, the anatomical factors affecting horizontal component of attachment loss have not been previously assessed. Therefore, this study determined the bucco-lingual measurements of the cemento-enamel junction and the mesial and distal roots and at the level of root separation. METHODS: One hundred extracted permanent human mandibular first (N = 50) and second (N = 50) molars were studied. Four horizontal bucco-lingual widths were measured with calibrated calipers: 1) furcation entrance/roof (FE); 2) cemento-enamel junction level (CEJ); 3) mesial root width (MRW); and 4) distal root width (DRW). RESULTS: The mean widths at FE, CEJ, MRW, and DRW were, respectively, 5.53 +/- 0.45 mm, 8.71 +/- 0.54 mm, 8.57 +/- 0.54 mm, and 7.97 +/- 0.65 mm in the first molars and 5.61 +/- 0.65 mm, 8.40 +/- 0.65 mm, 7.95 +/- 0.88 mm, and 7.16 +/- 0.84 mm in the second molars. Analysis of variance revealed significant differences between FE and the other variables tested. The results showed that the bucco-lingual width of the furcation roof is considerably shorter than the MRW and DRW. The difference in the mean bucco-lingual dimension between FE and the other measurements occurred in all teeth evaluated and varied between 0.7 and 4.30 mm. CONCLUSIONS: Our findings demonstrate that clinical measurements of horizontal probing depth that use the external surfaces of roots as reference points overestimate the true anatomical component of furcation involvement in mandibular molars. Conversely, positive treatment outcomes in these teeth may be underestimated. This has implications not only for clinical practice but also for clinical research studies evaluating treatment outcomes.

Furcation Defects↗
PubMed2004

Accuracy of supported root ratio estimation from projected length and area using digital radiographs.

BACKGROUND: The purpose of this study was to evaluate the accuracy of supported single-root surface ratio estimated from the length and projected area of the tooth, using digital dental radiographs. METHODS: Eight extracted, single-root teeth were three-dimensionally digitized using a contact technique for surface area measurement. The data were then processed using engineering application software and length, projection area, and true surface area of the root at a designated length were obtained. Based on these three measurements, the accuracy of the supported surface area ratio measurement at different lengths of the root was evaluated. RESULTS: The largest mean errors from linear and area estimation were 9.58% and -1.16%, respectively. The 95% confidence intervals were all positive, indicating that linear measurements overestimated supported ratio. T tests showed that linear estimations resulted in significant differences in all eight teeth and area estimations in five teeth. When analyzing the supported ratio of the alveolar bone receding from the cemento-enamel junction (CEJ) toward the apex of the root at each mm, linear estimation showed significant differences down to 8 mm, while area estimation showed significant differences only up to 2 mm. CONCLUSIONS: The results of this study indicate that a reliable estimate of the ratio of root surface area supported by alveolar bone cannot be determined from linear or area data. However, when the marginal bone destruction exceeds 2 mm from the CEJ, area estimation does not show a significant difference in the supported region. As demonstrated in this study, root surface ratio estimation function could be an advantage of digital dental x-ray systems in which projected root area is readily observed.

Alveolar Process↗
PubMed2005

A pilot study applying digital radiography for estimating ratio of supported single-root surface area.

BACKGROUND: The prognosis of a tooth with periodontitis is affected by the amount of supporting bone. A key factor in retaining a tooth is the ratio of supported root surface. Currently, root surfaces cannot be accurately measured using conventional dental radiographs, which only measure the length of bone support on proximal surfaces. METHODS: Eight extracted, single-rooted teeth were 3-dimensionally digitized using a contact technique for true surface area measurements. Root length, projection area, and pixel values were then measured on digital radiographs. The accuracy of the ratio estimation of supported surface area from linear, area, and pixel values was calculated and compared. RESULTS: The mean error from linear estimation was 7.9%; the mean error from area estimation was 1.0%; and the mean error from pixel value estimation was 1.3%. One-way analysis of variance (ANOVA) showed significant differences in all estimations while Scheffé's analysis further revealed significant differences only in the linear estimation. CONCLUSIONS: A three-dimensional digitizing device could be used as a non-destructive method of measuring root surface area. The ratio of supported single-root surface area could be estimated with high accuracy from the projected area data acquired on the digital dental radiographs. The thickness data as reflected from the pixel values in the digital images did not improve the estimation accuracy. Estimations using only length data yielded significantly less accuracy. Digital dental x-ray images provide the potential for estimating the ratio of supported root surface efficiently.

Analysis of Variance↗
PubMed2005

Trends of dental arc variation in a young adult male population and their meaning in the concept of occlusion.

To describe the variation of shape and size of dental arcs the method of principal components was applied. 27 measurements of every dental cast made from 50 young adult males with good occlusion were made, and the following parameters were calculated: 7 widths, 5 left chords, 5 right chords, 5 sagittal lengths (calculated as orthogonal to corresponding width) and 5 angles. Different sets of features were analyzed for both arcs together and for each arc separately. Three independent analyses by the method of principal components show a good description of the main trend of dental arc shape and size variation and a difference between the growth and variation of frontal and distal parts of the arcs. They also describe the variations of occlusion. The trends of dental arc variation ascertained help us to understand the nature of malocclusions and the causes of their preservation in evolution.

Adult↗
PubMed1989

[Study on determination of the imaginary axis of the tooth crown. 1. Measuring procedure].

The state of inclination and the change under various conditions of the imaginary axis of the tooth crown of upper jaw and lower jaw right and left first molar can be determined by the measuring apparatus and method of this study. 2. The measurement error of this method was not more than 0.1 degree. This value was sufficient for the purpose of this study.

Molar↗
PubMed2006

The relation between tooth shape ratio and incisor arrangement in Japanese children.

To investigate whether the relationship between tooth shape ratio and incisor arrangement proposed by Peck et al. in 1972 was applicable to Japanese children, we compared two groups, one with normal permanent dentition and another with crowded permanent dentition, using chronologically constructed plaster dentition models. Tooth shape ratio was obtained by dividing the incisor mesio-distal width by the labio-lingual width and then multiplying the result by 100. The results revealed a significant difference in the coronal mesio-distal diameter of the incisors between the two groups, but the other items showed no significant differences, suggesting no clear relationship between tooth shape ratio and incisor arrangement. That was, our results suggest that there is no clear relationship between tooth shape ratio of the mandibular incisors and arrangement of the permanent incisors in Japanese children.

Adolescent↗
PubMed2006

[Positional changes of the lower and upper anterior teeth after surgical correction of mandibular prognathism].

BACKGROUND/AIM: To establish the influence of surgical corrections of mandibular prognathism upon the position of the lower and upper anterior teeth (incisors). METHODS: The changes in position of the lower and upper anterior teeth (incisors) after the surgical correction of mandibular prognathism were analyzed by means of x-ray craniometry in 183 patients (female: n = 110, male: n = 73) in which the correction had been made in accordance with the principles of sagital osteotomy of the mandibular ramus. There were 4 angular and 2 linear parameters determined in the pre- and postoperative tele-x-ray-pictures. The changes of these parameters were tested by means of the parametric statistic tests. RESULTS: The performed surgical procedures did not cause statistically significant changes in the angular parameters. The changes of both linear parameters were thought highly statistically significant. CONCLUSION: Under the influence of the performed surgical procedures no changes were found in the position of anterior teeth (incisors) in relation to SN and the mandibular plane. They were actually moved along with the medium fragment of the lower jaw and that fragment was moved linearly backwards along the occlusal plane with a practically insignificant rotation in the cranial direction.

Adult↗