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We have applied mathematical morphology for fractal analysis of bone x-ray images. The digitized gray level image is treated as a three-dimensional surface whose fractal dimension is calculated by performing a series of dilations on this surface and plotting the area of the resulting set of surfaces against the size of the structuring element. This approach gives us the added advantage of encoding structural information via the use of a structuring element. The algorithm has been applied to several bone radiographs and the results demonstrate that the fractal dimension using mathematical morphology gives us a robust texture measure of trabecular bone structures.

Background: The aim of this 5-year follow-up study was to clinically and radiographically evaluate the long-term results after guided tissue regeneration (GTR) therapy of Class II furcation defects using non-resorbable and bioabsorbable barriers. Methods: Nine pairs of contralateral Class II furcation defects were treated in 9 patients with advanced periodontitis. Within each patient, one defect received a non-resorbable (expanded polytetrafluoroethylene [ePTFE]; control, C) barrier and the other a bioabsorbable (polyglactin 910; test, T) barrier by random assignment. At baseline, 6, and 60 +/- 3 months after surgery, clinical parameters and standardized radiographs were obtained. Gain of bone density within furcation areas was assessed using subtraction radiography. Results: Six and 60 months after GTR therapy, statistically significant (P <0.05) horizontal attachment (CAL-H) gain was observed in both groups (C6: 1.7 +/- 0.8 mm; C60: 1.6 +/- 1.2 mm; T6: 2.0 +/- 0.7 mm; T60: 2.2 +/- 0.9 mm). However, 1 furcation assessed as Class I six months after GTR therapy with a bioabsorbable barrier had progressed to Class III after 5 years, and in another patient, 5 years after placement of an ePTFE barrier, 1 furcation had lost all the CAL-H gain that had been observed at 6 months. Subtraction analysis revealed similar area gain in both groups 6 and 60 months postsurgically (C6: 0.3 +/- 0.5; C60 1.0 +/- 1.7; T6: 0.4 +/- 0.4; T60: 1.1 +/- 1.7). Conclusions: CAL-H gain achieved after GTR therapy in Class II furcations was stable after 5 years in 16 of 18 defects. The study failed to show a statistically significant difference in stability of CAL-H gain between control and test groups 5 years after GTR therapy. [ABSTRACT FROM AUTHOR]

Background: The exclusive use of mean measurements in periodontal research might at times be misleading, as changes in different sites in the same individual might nullify each other. The purpose of the present study was to compare disease progression and response to periodontal therapy using both individual site activity with thresholds and mean patient changes. Methods: Seventy-nine (79) subjects with established periodontitis were monitored for 1 year (no treatment [NTx] group); 108 subjects who received scaling, root planing, and quarterly prophylaxis were observed in a similar time interval (treatment [Tx] group). Probing depth (PD), attachment level (AL) and alveolar crestal height (ACH) were measured at baseline and 1 year using pressure-sensitive probes and computer-assisted image analysis of radiographs. Results: Mean reduction in PD (0.50 mm) was observed in the Tx group compared to a small increase (-0.04 mm) in the NTx group (P= 0.0001). Treatment resulted in mean AL gain (0.44 mm) compared to net AL loss (-0.21 mm) in the NTx group (P= 0.0001). Subjects in the Tx group had twice as many sites with AL gain (beyond the threshold) compared to NTx subjects (16.64+/-1.07% versus 8.11+/-0.68%) which was highly significant (P = 0.0001, Student t test). Similarly, although in the opposite direction, percentage of sites with AL loss beyond threshold was 6.21+/-0.47% (Tx group) and 14.02+/-1.15% (NTx group) which was also highly significant (P = 0.0001, Student t test). Change in ACH was minimal for the Tx group (-0.07+/-0.03 mm) while NTx subjects experienced greater bone loss throughout the year (-0.16+/-0.02 mm); percentage of sites with ACH loss was similar for both groups, while the Tx group had 3 times the number of sites with ACH gain (11.76% versus 3.42%), suggesting that the reduction in mean bone loss in the Tx group did not result from a reduction in losing sites, but rather from an increase in gaining sites. The use of both means and binary data seems to supplement the information regarding the nature and mechanism of disease progression and arrest. Conclusions: The characteristics of periodontal disease with its multifactorial patient, local, and site-related etiology support the use of both mean and site-based changes in clinical studies of periodontal disease and treatment. [ABSTRACT FROM AUTHOR]

This review defines terms such as accuracy, validity, and reliability, which are used to describe the quality of methods for taking x-rays and for analyzing digital images. Values for these parameters are described for techniques of taking standardized x-rays such as ear-rod fixation and fixation by use of teeth with a dental impression. In addition, values are given for linear measurements on digitized images and for quantitative image subtraction. Differences are addressed between quantitative subtraction with a reference ramp and relative subtraction using the computer-assisted densitometric image analysis (CADIA) system. The relationship between radiographic bone height and clinical attachment level is also discussed. Finally, present and future use in the periodontal office of linear radiographic measurements on digital images and digital subtraction is discussed. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to compare bone regeneration as assessed by subtraction radiography with clinical attachment measurements 24 months after regenerative surgery. Methods: In 24 patients with advanced periodontitis, 34 Class II and 10 Class III furcations were treated by guided tissue regeneration using expanded polytetrafluoroethylene (n = 18) or bioabsorbable barriers (n = 26). Clinical parameters were assessed and 40 pairs of standardized radiographs were taken before and 24 months after surgery. Bony gain within furcations was assessed using subtraction analysis. Results: In Class II furcations, statistically significant (P <0.001) vertical (CAL-V: 1.06+/-1.56 mm) and horizontal (CAL-H: 2.05+/-1.24 mm) attachment gain was observed 24 months postsurgically. Within Class III defects CAL-V gain was assessed 1.78+/-1.43 mm (P <0.005). CAL-H gain in buccal and lingual Class II furcations was explained by the relative density gain, baseline CAL-H, gingival index (GI) reduction, and individual patients (P <0.001) whereas, multiple regression analysis failed to show a relation between CAL-H gain and any of the subtraction parameters for interproximal furcations. Vertical attachment gain in interproximal sites was explained by net bony area gain (subtraction), PD and GI reduction, baseline CAL-V, defect type, smoking, and individual patients (P<0.001). Conclusions: There was a statistically significant correlation between clinical and radiographic improvements within furcation defects. However, this correlation was modulated by other factors such as baseline CAL-V or CAL-H, PD and GI reduction, or smoking. The relative density gain seemed to sufficiently describe bony changes related to clinical changes within buccal and lingual furcations, whereas bone area gain suitably described bony changes in interproximal Class II and III furcations. [ABSTRACT FROM AUTHOR]