Three-Dimensional Alveolar Bone Anatomy of the Maxillary First Molars: A Cone-Beam Computed Tomography Study With Implications for Immediate Implant Placement

Purpose: To retrospectively evaluate alveolar dimensions of healthy maxillary first molars (MFMs), which have implications for (immediate) implant placement and endodontic therapy. Materials and Methods: Conebeam computed tomographic records of 95 patients (150 MFMs) were used [32 men and 63 men, aged 37.2 (14.9) years]. The vertical distance from sinus floor (SF) and MFM apexes (mesio-buccal [MB] and disto-buccal [DB]) and also distance between root apexes (spreading of the roots, MB to palatal and DB to palatal, representing bone width) were measured. Result: The mean (SD) thickness of buccal and palatal bony walls (2 mm from crest) was 1.58 (0.6) mm and 1.34 (0.54) mm, respectively. The mesio-distal and bucco-lingual socket sizes at crest were 7.3 (0.84) mm and 10.5 (0.90) mm, respectively. The mean distance from SF to MFM furcation was 6.51 (2.94) mm. The mean distance (95% confidence interval) between SF and MB, DB, and palatal apexes was -0.36 mm (-0.91 to 0.19), 0.32 mm (-0.27 to 0.9), and -2.2 mm (-2.7 to -1.7), retrospectively. Significant differences were found for root apex distances to SF for MB versus palatal roots and DB roots versus palatal roots, but not for MB versus DB roots (P < 0.05). Conclusion: The present findings on MFM dento-alveolar morphology, in particular high intrusion of palatal roots into SF, can be used as a clinical risk management tool for immediate implant placement and endodontic therapy.