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Treatment Algorithm · Module
Match the drill to the bone: protocol by density
Adapting the osteotomy to bone quality to maximize primary stability without thermal or mechanical injury. Built on the Lekholm & Zarb classification and contemporary drilling-modification evidence.
Use: Surgical drilling reference
Goal: Primary stability
Framework: Lekholm & Zarb · ITI
01 — Classification
Lekholm & Zarb bone types
Bone quality is graded I–IV by the ratio of cortical to trabecular bone (Lekholm & Zarb, 1985). Density drives drilling strategy: dense bone risks overheating and over-compression, soft bone risks inadequate stability.
Type I
Dense cortical (D1)
- Almost entirely homogeneous compact bone
- Typical: anterior mandible
- Risk: overheating, low vascularity
- High primary stability, slower remodeling
Type II
Thick cortex + dense core (D2)
- Thick cortical layer around dense trabecular bone
- Typical: posterior mandible, anterior maxilla
- Considered ideal for implants
- Reliable primary stability
Type III
Thin cortex + dense core (D3)
- Thin cortex, moderately dense trabecular bone
- Typical: anterior/posterior maxilla
- Moderate primary stability
- Benefits from under-preparation
Type IV
Thin cortex + sparse core (D4)
- Thin/absent cortex, low-density trabecular bone
- Typical: posterior maxilla
- Hardest site for primary stability
- Candidate for osseodensification
02 — Decision Pathway
Interactive drilling-protocol selector
Select the bone type assessed on CBCT and confirmed by tactile feedback at the pilot drill. Each pathway gives the recommended osteotomy modification and the realistic stability target.
Tap the bone type for this site.
Step 1 — What is the bone quality?
TYPE I (D1)
Dense cortical
Hard, low-vascularity bone.
TYPE II (D2)
Thick cortex + dense core
The favorable default.
TYPE III (D3)
Thin cortex, moderate core
Softer; stability needs help.
TYPE IV (D4)
Soft, sparse trabecular
Lowest stability risk.
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03 — Quick Reference
Bone type → protocol → stability
A summary mapping. Protocols are general principles — always follow the implant manufacturer's drilling sequence and adjust to intraoperative tactile feedback.
| Type | Typical site | Drilling protocol | Expected primary stability |
|---|
| I (D1) | Anterior mandible | Full sequence + tapping/countersink; copious irrigation, low speed to avoid overheating; avoid over-compression | High |
| II (D2) | Posterior mandible, anterior maxilla | Standard manufacturer sequence; minimal or no tapping | High |
| III (D3) | Maxilla (variable) | Under-preparation (final drill skipped/undersized); engage available cortex; osseodensification optional | Moderate |
| IV (D4) | Posterior maxilla | Under-preparation + osseodensification; bicortical/sinus-floor engagement; avoid over-prep and tapping | Low → needs augmentation of technique |
Reference
Sources & clinical disclaimer
For licensed clinicians — educational use only. This algorithm summarizes published consensus and is not a substitute for individual clinical judgment, examination, or the standard of care in your jurisdiction. Drilling sequences are implant-system specific — always follow manufacturer instructions for use and calibrate to intraoperative tactile and torque feedback.
- Lekholm U, Zarb GA. Patient selection and preparation. In: Brånemark P-I, Zarb GA, Albrektsson T, eds. Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago: Quintessence; 1985:199–209.
- Misch CE. Bone density: a key determinant for treatment planning. In: Contemporary Implant Dentistry. 3rd ed. St. Louis: Mosby Elsevier; 2008:130–146.
- Greenstein G, Cavallaro J. Implant insertion torque: its role in achieving primary stability of restorable dental implants. Compend Contin Educ Dent. 2017;38(2):88–95. (Consistent with ITI guidance on stability and drilling modification.)
Last reviewed: June 2026 · Next review due: June 2027 · Version 1.0