Bone volume and interdental space
- Consider available jaw bone volume in transversal (mesio-distal) and vertical dimensions using conventional intraoral radiographs. Sagittal (buccolingual) bone dimension is preferably evaluated with cross-sectional imaging.
- Base treatment options on available bone dimensions.
- Beware of root anatomy of adjacent teeth.
Bone volume/interdental space
Residual bone volume in a single-tooth gap is mainly reflected by the cause of the missing tooth. A preserved gap due to aplasia implies an under-developed alveolar crest, mainly in bucco-lingual dimension, whereas defects after extraction of compromised teeth may involve all bone dimensions. Residual bone volumes in upper lateral incisor and lower central/lateral incisor regions frequently present with transversal dimension of 5-6 mm and sagittal dimension of <4 mm, respectively.
Figure 1: Insufficient sagittal bone dimension in upper lateral incisor region
Figure 2: Reduced interdental space in upper lateral incisor region
In the case of virgin adjacent teeth consider orthodontics, a resin-bonded fixed partial denture, or bone augmentation for subsequent implant placement.
Evaluate residual bone height with sufficient bucco-lingual width above the mental foramen and the lower alveolar nerve prior to implant treatment. A majority of posterior mandibular cases require cross-sectional images. Always secure an apical safety distance between the site preparation and nerve structures.
Missing upper bicuspids or molars generally imply downward expansion of the maxillary sinus, which in turn may interfere with conventional implant treatment. The altered anatomy may call for various treatment options such as augmentation procedures or conventional tooth-supported prosthetics.
Beware of apically converging roots of adjacent teeth, which may intervene with implant placement in terms of accidental contact with the periodontal ligament or root cementum. Occasionally the blood vessel entering the apex of a converging root may be cut off during site preparation, resulting in pulp necrosis.
To assess the properly the available bone volume when a single tooth is missing, after the conventional intra-oral radiograph has been examined, cross-sectional imaging may be needed especially in the vicinity of anatomical landmarks such as nerves and vessels.”