Three-dimensional macroscopical quantification of plaque accumulation on implant-supported fixed complete dental prostheses surfaces: A methodological pilot study.

STATEMENT OF PROBLEM: Area calculation is the primary method for quantitatively analyzing accumulated plaque on the intaglio surfaces of implant-supported fixed complete dental prostheses (IFCDPs). However, the classic calculation method for stained dental plaque is based on two-dimensional (2D) photographs, which could mislead the three-dimensional (3D) representation of an object's actual morphology, especially when a surface is not flat. PURPOSE: This pilot in vitro study, used for methodological purposes, evaluated the repeatability and precision of a 3D area calculation method to analyze simulated accumulated biofilm on the intaglio surfaces of an IFCDP. MATERIAL AND METHODS: The titanium framework of an IFCDP with a smooth intaglio surface was prepared with 8 milled sites and scanned by microcomputed tomography. Out of these, 4 sites were cubic (set sides lengths=1, 2, 3, and 4 mm), and 4 sites were hemispherical (set diameters=1, 2, 3, and 4 mm). A green-colored aerosol was sprayed onto the carved-out intaglio sites. The framework intaglio surface was 3D-scanned (n=10) and 2D-photographed (n=10) at 10 different photo angles. Two raters twice measured the 3D and 2D data from the carved-out sites' green-colored area one week apart. Intraobserver repeatability and interobserver reliability were evaluated with an independent t test. The deviation between the measurements and the microtomography values was calculated. Pearson's correlation coefficient (r) evaluated the repeatability of multiple measurements. A standard level of significance was set at α=.05. RESULTS: The differences between the 2D photographs and the microtomography values were statistically significant (P<.001), whereas the differences between the 3D scans and the microtomography values were not significant (P=.063). The overall differences between the microtomography values and the 3D measurements were smaller (2.15 ±2.30 mm2 vs. 18.91 ±22.78 mm2, P=.055) than the differences between the microtomography values and the 2D measurements. The percentage differences between the microtomography values and the 3D measurements were significantly smaller (10.41 ±8.33% vs. 65.66 ±19.22%, P<.001) than the microtomography differences values with the 2D measurements. The measurement differences between the microtomography value and the 3D measured hemispherical site data were significantly smaller than the measurement differences between the microtomography values and the 3D measured cubical site data (P=.026). The 2D method had "poor" repeatability among the 10 different shot angles (r=0.391, P<.001), whereas the 3D method had "good" repeatability among the 10 scans (r=0.999, P<.001). CONCLUSIONS: An irregular intaglio surface of an IFCDP could accurately and repeatedly be recorded and analyzed by a 3D area calculation method. This color-matching assessment of the topological environment is expected to be adopted in future studies.

Comparison of Measurements on Cone Beam Computed Tomography for Periodontal Intrabony Defect with Intra-surgical Measurements.

OBJECTIVE: To explore the relationship between cone beam computed tomography (CBCT) measurements and direct measurements during the surgery to correct intrabony defects. METHODS: Forty-four patients with 44 intrabony defects who finished initial periodontal therapy and were considered for periodontal surgery were recruited. Digital periapical radiography and CBCT was performed before the surgery. The distance from the bottom of the defect to the cementoenamel junction (CEJ-BD), the depth and mesio-distal width of the defect were measured on CBCT, periapical radiographs and during the surgery. The buccal-lingual width of the defect was only recorded on CBCT and during the surgery. Lastly, intra-surgical linear measurements were compared with measurements of radiographs and CBCT, respectively. RESULTS: The means of the intra-surgical CEJ to BD, the depth of the defect, the mesio-distal (M-D) width and the buccal-lingual (B-L) width of the defect were 8.90 mm, 5.52 mm, 3.35 mm and 7.40 mm, respectively. Between CBCT measurements and surgical measurements the differences for the CEJ to BD (0.76 ± 1.40 mm) and the depth of the defect (0.63 ± 1.67 mm) were statistically significant, but the differences for the M-D width (-0.17 ± 0.67 mm) and the B-L width (-0.16 ± 0.65 mm) of the defect were not statistically significant. CONCLUSION: CBCT could provide relatively accurate measurements of the M-D width of the defect and additionally showed accurate measurements of the B-L width of the defect which periapical radiographs could not show. However, for vertical measurements of the intrabony defect (CEJ to BD and depth of the defect), when compared with measurements during the surgery, CBCT showed no advantages over periapical radiographs. A new method should be developed for accurately measuring the periodontal intrabony defects using CBCT in the future.