Table 7.

Four types of anatomical characteristics of maxillary anterior teeth for immediate implant according to the sagittal root angle with surrounding hard and soft tissue

Anatomical type	Angle	n	Index		Result	Significance	Implication for immediate implant design	Schematic map of implant(Bone level NC, Straumann; 3.3*12 mm)
Type I	< 0°	9	Coronary buccal bone and gingiva	Bone	< 1 mm	High risk of buccal bone wall defect when placing the implant	The implant could be place along the axis of tooth, while the palatal bone Under the CEJ should be noted to keep contact (> 1 mm at least)
				Gingiva	No correlation	/
			Coronary palatal bone		1.5–1.7 mm	Relative thin for offering alternative bone
			Apical bone	Labial	1.0–3.0 mm	Ensuring sufficient primary stability for immediate implant
				Palatal	2.0–4.0 mm	Relative thick for offering alternative bone
			Under apex bone along the tooth axis		8.4 mm	To get enough primary stability
			Root diameters		No correlation	/
Type II	0°–10°	125	Coronary buccal bone and gingiva	Bone	0.51–1.20 mm	High risk of buccal bone wall defect when placing the implant	The implant could be place along the axis of tooth, which was the best anatomic situation (not only the angle, but the surrounding bone) for immediate implantation
				Gingiva	No correlation	/
			Coronary palatal bone		1.6–2.2 mm	Relative thick that could be used to adjust implant to proper position
			Apical bone	Labial	1.0–3.0 mm	Ensuring sufficient primary stability for immediate implant
				Palatal	2.3–5.1 mm	Thick for offering alternative bone
			Under apex bone along the tooth axis		9.9–10.1 mm	To get enough primary stability
			Root diameters		No correlation	/
Type III	10°–25°	545	Coronary buccal bone and gingiva	Bone	0.50–1.03 mm	High risk of buccal bone wall defect when placing the implant	The implant was recommended to rotate palatally at the apical direction to protect the buccal bone wall around the apex. Intro-mouth adhesive of the crown and even angled implant base might be used during final restoration
				Gingiva	No correlation	/
			Coronary palatal bone		1.7–3.1 mm	Adequate bone dimension that could be used to adjust implant to proper position
			Apical bone	Labial	0.9–2.1 mm	< 1 mm usually indicates high risk of fenestration and perforation during implant placement
				Palatal	3.1–8.1 mm	/
			Under apex bone along the tooth axis		6.4–9.4 mm	Abundant bone for getting enough primary stability
			Root diameters		No correlation	/
Type IV	> 25°	121	Coronary buccal bone and gingiva	Bone	< 1 mm	High risk of buccal bone wall defect when placing the implant	The implant has to rotate palatally to protect the buccal bone wall. Angled implant base would be used during final restoration or immediate implant was not recommended on the consideration of long-term success
				Gingiva	No correlation
			Coronary palatal bone		2.2–4.3 mm	Adequate bone dimension that could be used to adjust implant to proper position.Adequate bone dimension that could be used to adjust implant to proper position
			Apical bone	Labial	0.8–1.4 mm	< 1 mm usually indicates high risk of fenestration and perforation during implant placement
				Palatal	4.4–10.3 mm	/
			Under apex bone along the tooth axis		2.9–4.6 mm	High risk to get enough primary stability
			Root diameters		No correlation	/