Evaluation of the Anastomosis Canal in Lateral Maxillary Sinus Wall With Cone Beam Computerized Tomography: A Clinical Study
This clinical study used cone beam computerized tomography (CBCT) to locate the position of the anastomosis canal in lateral wall of maxillary sinuses, and to evaluate the thickness of lateral sinus wall and the distance from the lower border of the canal to the sinus floor, which could provide surgeon with information about this anastomosis. Two hundred and forty-two (242) volumes of CBCT scans were included in this study. The distances from the lower border of the anastomosis canal to the sinus floor and from the maxillary alveolar crest to the sinus floor were evaluated in transversal plane, and the thickness of the lateral sinus wall was measured at the distance of 3, 6, 9 mm from the sinus floor and at the level of the lower border of the canal at the same plane. The canal was identified in 87.6% (424/484) of the sinus. Most canals were intraosseous, or beneath the sinus membrane. The mean distance was 9.2 ± 3.5 mm from the lower border of the canal to the sinus floor, and 10.8 ± 4.0 mm from the alveolar crest to the sinus floor. The thickness of the lateral sinus wall was 2.4 ± 0.9 mm, 1.8 ± 0.8 mm, 1.7 ± 0.7 mm, 1.8 ± 0.8 mm at the distance of 3, 6, 9 mm from the sinus floor and at the level of the lower border of the canal. The location of the anastomosis canals varied from each patient, but the distance from the sinus floor was similar in different teeth sites. The sinus floor could be an anatomic landmark of sinus floor augmentation. In order not to interrupt this canal, great care must be taken by the implant surgeon to identify this canal.
Figure 1. Canal of anastomosis of sinus lateral wall in the cone beam computerized tomography scan. (a) Type I: on the external cortex of the lateral sinus wall. (b) Type II: intraosseous. (c) Type III: beneath the sinus membrane. Figure 2. Measurements of the distance from the lower border of the canal to the sinus floor (D1) and the distance from the alveolar crest to the sinus floor (D2). (a) D1, tooth site #4. (b) D2, tooth site #4. Figure 3. Measurements of bone thickness of the lateral sinus wall. BTD indicates bone thickness of the lower border of the canal.
Figure 4. The distribution of each type of canal in different teeth sites. Second premolar: 24 canals of type I, 207 of type II, and 193 of type III. First molar: 3 canals of type I, 94 of type II, 327 of type III. Second molar: 22 canals of type I, 222 of type II, 180 of type III. There was significant difference between first molar and other sites (P < .0001) and type in second premolar had no difference with second molar (P = .521). Figure 5. The distance from the lower border of the canal to the sinus floor in each tooth site. There was no significant difference among sites (P > .05), 20 canals located ≤3mm from the sinus floor, 215 canals were >3 mm and ≤6 mm from the sinus floor, 453 canals were >6 mm and ≤9 mm from the sinus floor, 584 canals were >9 mm from the sinus floor.
The correlation of the distance from the lower border of the canal to the sinus floor (D1) and the distance from the alveolar crest to the sinus floor (D2), D2 and the bone thickness of the lower border of the canal (BTD). There was negative correlation between D1 and D2 (P < .0001), and positive correlation between D2 and BTD (P < .0001) in each tooth site.
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