CBCT assessment of alveolar bone wall morphology and its correlation with tooth angulation in the anterior mandible: a new classification for immediate implant placement.

PURPOSE: This study aimed to quantify alveolar bone morphology, demonstrate the relationship between tooth angulation and alveolar bone thickness, and introduce a new classification for anterior mandibular teeth related to immediate implant placement (IIP). METHODS: Cone-beam computed tomography (CBCT) images of 211 anterior mandibular teeth were analyzed in sagittal slices to measure the thickness of the facial alveolar bone crest (FAB1) and apex (FAB2), and the lingual alveolar bone crest (LAB1) and apex (LAB2). Tooth angulation was classified as 1°-10°, 11°-20°, and >20° according to the tooth's long axis and alveolar bone wall. Spearman correlation coefficients were used to evaluate correlations between the variables. RESULTS: FAB1 and LAB1 were predominantly thin (<1 mm) (84.4% and 73.4%, respectively), with the lateral incisors being thinnest. At the apical level, FAB2 and LAB2 were thick in 99.5% and 99.1% of cases, respectively. Significant differences were documented in FAB2 (P=0.004), LAB1 (P=0.001), and LAB2 (P=0.001) of all mandibular teeth. At all apical levels of the inspected teeth, a significant negative correlation existed between TA and FAB2. Meanwhile, TA showed a significant positive correlation with LAB2 of the lateral incisors and canines. These patterns were then divided into class I (thick facial and lingual alveolar bone), class II (facially inclined teeth) with subtype A (1°-10°) and subtype B (11°-20°), and class III (lingually inclined teeth) with subtype A (1°-10°) and subtype B (11°-20°). CONCLUSIONS: Mandibular anterior teeth have predominantly thin facial and lingual crests, making the lingual bone apical thickness crucial for IIP. Although anchorage can be obtained from lingual bone, tooth angulation and tooth types had an impact on IIP planning. Hence, the new classification based on TA and alveolar bone wall may enable rational clinical planning for IIP treatment.

Qualitative and Quantitative Assessments of Alveolar Bone Dimension and Its Correlation with Tooth Angulation in the Anterior Maxilla for Immediate Implant Placement.

AIM AND OBJECTIVE: The aim of this paper is to ascertain the quantitative measurements of alveolar bone thickness at all maxillary anterior teeth and qualitatively demonstrate the relationship between tooth angulation (TA) and alveolar bone thickness. MATERIALS AND METHODS: Cone-beam computed tomography (CBCT) images of 189 maxillary anterior teeth were collected. Sagittal view was selected to perform the measurement on alveolar bone wall at crestal, midlevel, and palatal. TA was measured along to the tooth long axis (TLA) related to the alveolar bone housing. Spearman's correlation coefficients were conducted to test the correlation between the variables. RESULTS: The facial alveolar bone (FAB) is predominantly thin (<1 mm) at the crestal and midroot region. A significant difference was recorded in the median thickness of FAB at the midroot and apical area (p = 0.001, p = 0.021). The FAB thickness was not gradual with midroot being thinner than crestal. For the palatal alveolar bone (PAB), the thickness was increased continuously toward the apex. At all apical levels of inspected teeth, a significant negative correlation existed between TA and FAB. A positive correlation of TA was only significant at the facial crest of lateral incisor (r = 0.308). However, the canines did not correlate with the FAB, but correlated with the PAB at the apical level (r = 0.478). CONCLUSION: The FAB wall crest of maxillary anterior teeth was generally thin and not gradual with the lateral incisor being the thinnest. A significant correlation of TA existed based on different types of maxillary anterior teeth and alveolar bone level. The maxillary anterior teeth with increased buccolingual angulation were correlated with thicker bone at the apical level. CLINICAL SIGNIFICANCE: The quantitative assessment of FAB and TA in degree may serve as an anatomical index for ideal implant position.

Quantitative and qualitative assessments of intraosseous neurovascular canals in dentate and posteriorly edentulous individuals in lateral maxillary sinus wall.

OBJECTIVE: Knowledge and evaluation of the blood supply within the maxillary sinus before sinus augmentation are vital to avoid surgical complications. The lateral maxilla is supplied by branches of the posterior superior alveolar artery and infraorbital artery forming intraosseous anastomoses (IA) within the bony lateral antral wall. This study was undertaken to (i) measure mean diameter of IA and its distance from the alveolar ridge within dentate and posteriorly edentulous subjects and, (ii) qualitatively display the relationship of IA throughout its course within the lateral maxillary sinus in cone beam computed tomography (CBCT). METHOD: Maxillary CBCT images of two-hundred-and-fifty-seven consecutive patients (163 men, 94 women, mean age 42 years) were analyzed. Samples were later divided into dentate (n = 142) and posteriorly edentulous (n = 115) jaws. Using both alveolar ridge and tooth location as reference points, the distance and diameter of IA were assessed. RESULT: The IA was seen in 63.7% of all sinuses with 68.2% in dentate and 62.4% in edentulous. Mean distance and diameter of IA across the posterior tooth locations were 17.9 ± 3.0 mm and 1.4 ± 0.5 mm (dentate) and 15.1 ± 3.0 mm and 1.0 ± 0.5 mm (posteriorly edentulous), respectively. In each sample, there were no significant differences in distance-alveolar ridge and no significant correlations in diameter-tooth location. A statistically significant Pearson coefficient correlation between diameter and distance in dentate state was observed (r = -0.6). CONCLUSION: This study reveals that dentate maxillary jaws present larger diameters as compared to posteriorly edentulous jaws, although the IA course remains the same. As these canal structures contain neurovascular bundles with diameters that may be large enough to cause clinically substantial complications, a thorough pre-surgical planning is therefore highly advisable.