The ISQ scale, on one page
The implant stability quotient maps resonance frequency analysis to a 1-100 scale. These charts summarize common literature conventions, not treatment thresholds.
ISQ stability bands
| ISQ range | Band | Cautious reading |
|---|---|---|
| 70-100 | High | Commonly treated as high stability, but not sufficient by itself for immediate or early loading. |
| 60-69 | Medium | Follow-up measurement and the broader case context usually matter more than the isolated value. |
| 1-59 | Low | Often read cautiously with conventional unloaded healing and re-measurement language. |
Bone density: Misch D1-D4 and Lekholm & Zarb
| Misch | Lekholm & Zarb | Description | Typical sites |
|---|---|---|---|
| D1 | Type I | Dense cortical bone | Anterior mandible |
| D2 | Type II | Thick porous cortical, coarse trabecular | Anterior/posterior mandible |
| D3 | Type III | Thin porous cortical, fine trabecular | Anterior maxilla, posterior mandible |
| D4 | Type IV | Fine trabecular bone | Posterior maxilla |
Reading ISQ with insertion torque
ISQ and insertion torque describe different aspects of stability. A 2018 review and a 2026 meta-analysis do not frame the relationship identically, so this reference treats them as complementary values with heterogeneous evidence. Neither value is a stand-alone loading rule.
Reading a stability trend
Two measurements say more than one. A baseline ISQ at placement and a later value before loading show whether stability is rising, flat, or falling. Early-healing RFA studies describe stability decreases during the first weeks after placement, but the exact timing varies by study and case context. Interpret your values with the Stability Interpreter.
Sources
The bands and classifications above follow commonly cited literature conventions. Where sources differ, the page uses the narrower wording.
- Meredith N. Assessment of implant stability as a prognostic determinant. Int J Prosthodont. 1998;11(5):491-501. PubMed
- Sennerby L, Meredith N. Implant stability measurements using resonance frequency analysis: biological and biomechanical aspects and clinical implications. Periodontol 2000. 2008;47:51-66. PubMed
- Lekholm U, Zarb GA. Patient selection and preparation. In: Branemark P-I, Zarb GA, Albrektsson T, eds. Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago: Quintessence; 1985.
- Misch CE. Contemporary Implant Dentistry. St. Louis: Mosby/Elsevier - bone density classification (D1-D4).
- Ottoni JM, Oliveira ZF, Mansini R, Cabral AM. Correlation between placement torque and survival of single-tooth implants. Int J Oral Maxillofac Implants. 2005;20(5):769-776. PubMed
- Lages FS, Douglas-de Oliveira DW, Costa FO. Relationship between implant stability measurements obtained by insertion torque and resonance frequency analysis: a systematic review. Clin Implant Dent Relat Res. 2018;20(1):26-33. PubMed
- Tisci A, Fanelli F, Caponio VCA, Zhurakivska K, Dioguardi M, Troiano G. Resonance Frequency Analysis and Clinical Outcomes in Implant Dentistry: A Systematic Review and Meta-Analysis. Clin Implant Dent Relat Res. 2026;28(3):e70156. PubMed
- Shokri M, Daraeighadikolaei A. Measurement of primary and secondary stability of dental implants by resonance frequency analysis method in mandible. Int J Dent. 2013:506968. PubMed
- Ersanli S, Karabuda C, Beck F, Leblebicioglu B. Resonance frequency analysis of one-stage dental implant stability during the osseointegration period. J Periodontol. 2005;76(7):1066-1071. PubMed
- Esposito M, Grusovin MG, Maghaireh H, Worthington HV. Interventions for replacing missing teeth: different times for loading dental implants. Cochrane Database Syst Rev. 2013. Cochrane Library