1. Gingival level: The gingival level of the failing tooth should be (1) the same as (or more coronal than) that of the contralateral tooth and (2) harmonious with adjacent dentition, because some gingival recession can be expected after the procedure (Figure 8-1).¹ Therefore, when the gingival level of the failing tooth is more apical than that of the contralateral tooth, orthodontic forced eruption, if possible, should be implemented before IIPP.²¹

2. Osseous-gingival tissue relationship: The osseous-gingival tissue relationship can be evaluated by bone sounding, which entails probing until the bone crest is detected. The bone sounding measurement is the distance between the soft tissue crest and the bone crest. When the bone sounding measurements on the facial and proximal aspects of the tooth are about 3 and 4.5 mm, respectively, they are considered “normal crest.”¹⁹ When the bone sounding measurements are greater or less than “normal,” they are classified as “low crest” or “high crest,” respectively.¹⁹ With a low crest, tissue recession tends to occur after extraction, with or without immediate implant placement.¹⁹ Therefore, for IIPP the bone sounding measurements should be 3 mm on the facial aspect of the failing tooth and 4.5 mm on the proximal aspect of adjacent teeth (Figure 8-2). Depending on the gingival level, a compromised osseous-gingival relationship can be improved by orthodontic or periodontal treatments, or both.

3. Gingival biotype: The gingival biotype can be assessed during bone sounding and categorized according to the visibility of the underlying periodontal probe (SE Probe SD12 Yellow; American Eagle Instruments, Missoula, Montana) through the gingival tissue. If the probe is visible, the patient has a thin biotype; if it is not visible, the patient has a thick biotype (see Figure 8-2).^22,23 A thin gingival biotype, which has been shown to sustain more tissue recession after surgical insults than a thick biotype, can be enhanced by using a bilaminar subepithelial connective tissue graft (SCTG) at the time of IIPP.¹⁸

4. Sagittal root position (SRP): The sagittal root position of the failing tooth in the alveolar bone can be identified with cone beam computed tomography (CBCT) and can be categorized as one of four different classes (Box 8-1 and Figure 8-3).²⁰ Because changing the SRP is impractical, it is important for practitioners to recognize cases that are favorable for IIPP (Class I SRP), cases that are more technique sensitive and entail additional attention (Class II and Class III SRP), and cases in which IIPP is contraindicated and hard and/or soft tissue augmentation is required before implant placement (Class IV SRP).²⁰

5. Buccolingual width and interradicular mesiodistal widths: The buccolingual width and interradicular mesiodistal widths of the failing tooth determine the diameter of the implant to be used. These widths can be evaluated using CBCT and periapical radiographs (Figure 8-4).