195 CT scans from a private practice were examined. Measurements were made with computer software (Simplant) at 5mm intervals. Patients were categorized as to age, sex, and missing posterior teeth.
The following data emerged at the 95% confidence level (Excerpted from Table 1):
Distance from the crest to the inferior alveolar nerve at the first molar:
In males with no missing teeth : 13.85mm
In females with no missing teeth : 12.50mm
In males with missing posterior teeth: 10.20mm
In females with missing posterior teeth: 8.96mm
Other measured variables were available bone volume from the alveolar nerve to the inferior border of the mandible, the buccal cortex and the lingual cortex.
A high degree of variability in mandibular bone volume surrounding the inferior alveolar nerve. Greater risk of injury for females. CT scan should be considered when limited bone above the nerve is observed in conventional radiographs.
Dr GebrAel’s comments:
A must read (and re-read) article giving helpful average measurements as they relate to implant placement in the posterior mandible.
For more information PLEASE Refer To:
Radiographic Considerations for the Regional Anatomy in the Posterior Mandible
Natasha Yashar, Christopher G. Engeland, Alan L. Rosenfeld, Timothy P. Walsh, Joseph P. Califano
Journal Of Periodontology Jan 2012, Vol. 83, No.1, Pages 36-42
This website is added to my favorites list and the reason is obvious!! All the articles are well researched and very informative. Keep up the good work Dr. Gebrael!
This is an interesting study however, if you delve deeper into the literature there is compelling evidence that CBCT technology and the associated software programs are not accurate. Margins of error of up to 3 mm have been documented. Food for thought.
Thanks Dr Bassel…These quick overviews of relevant and current topics are a very concise approach, that encapsulates the findings in the article! A great resource at a time when we are overwhelmed at times with info.
That is interesting there is a risk difference based on gender. Im important point on the relevance of CT scans!!
It is always good to have averages in mind. However, we are better to consider paraclinical measurments such as CBCT or direct measurments (immediate implant cases) for all dental implant cases to be accurate and on the safe side.
Thank you Dr. Bassel G for a great review.
I think this study shows the importance of realizing the position of the inferior alveolar nerve in relation to implants since most of the current lawsuits relate implant and nerve injury.
I have published a paper with my graduate student (Natalie and Galil and Wilson 2013 ) also on Ct scan and show the distance also hope you like it