Anatomical considerations for implant placements in first maxillary molar extracted sites in East Asian patients

With the advent of cone-beam computed tomography (CBCT) for maxillofacial imaging, there has been a paradigm shift from two dimensional panoramic radiography to three dimensional imaging. This study investigated the microanatomy of the maxillary permanent first molar socket and its relationship to the floor of the maxillary sinus, especially for immediate or early implant placement.

Sixty CBCT scans of 30 Malay and 30 Chinese subjects were selected from over 300 archived images. Ninety-five percent of the subjects had sinus floor extending anterior to the first molar, while 72% had the floor dipping between the roots. Seventy-five percent of the patients had inter-radicular bone and almost 50% had intrusion of root apices into the floor of the maxillary sinus. The dimensions of the socket were as follows: the mean width was 11.42 ± 0.86 mm; the mean length was 7.70 ± 0.56 mm; the mean height on the coronal plane was 6.48 ± 3.77 mm while on the sagittal plane it was 6.85 ± 3.67 mm.

Any implant length greater than the mean height of the socket (approximately 7 mm) has a fair chance of perforation into the maxillary sinus if placed without any additional adjunct procedures. In addition, 50% of the apices opened into the maxillary sinus, thereby risking the creation of perforations or root displacements into the maxillary sinus during exodontia-mandating CBCT scanning prior to any surgical implant procedures.