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| Title |
Preoperative Identification of the Inferior Alveolar Nerve Anterior Loop via CBCT Imaging Can Influence Implant Treatment Planning |
| Clinical Question |
In patients requiring mandibular implant placement anterior to the mental foramen, what percentage of these patients have a radiographically identifiable anterior loop of the inferior alveolar nerve? |
| Clinical Bottom Line |
In patients requiring mandibular implant placement anterior to the mental foramen, pre-operative identification of the inferior alveolar nerve anterior loop with CBCT can have an influence on surgical treatment planning. This is based on two retrospective case reports involving a total of 776 subjects showing both a varying range of alveolar nerve anterior loop lengths and differing accuracy between CBCT and panoramic imaging. |
| Best Evidence |
(you may view more info by clicking on the PubMed ID link) |
| PubMed ID |
Author / Year |
Patient Group |
Study type
(level of evidence) |
| #1) 24583891 | Filo/2014 | 694 CBCT scans | Case Control Study | | Key results | Defining the anterior extension of the alveolar nerve (aAL) as the distance between the anterior border of the mental foramen and the anterior border of the alveolar nerve loop, this study found that 69.73% of patients had a mean aAL value of 1.16 mm. Furthermore, the range of aAL was 0.3-5.6 mm with 95.81% of the values in the 0-3 mm range; thus, assuming a safety margin of 3 mm anterior to the mental foramen, there would still be an approximate 4% potential for nerve injury with implant placement in patients with an aAL. | | #2) 25549693 | Vujanovic-Eskenazi/2015 | 82 partially or totally edentulous healthy patients | Case Control Study | | Key results | Although not statistically significant, the presence of an anterior loop of the alveolar nerve was identified in 36.6% of subjects using panoramic radiography compared to 48.8% of subjects using CBCT. | |
| Evidence Search |
"Cone-Beam Computed Tomography"[Mesh] AND "Mandibular Nerve"[Mesh] |
Comments on
The Evidence |
Validity: The Filo study, although not a meta-analysis, involved CBCT scans only (the gold standard in imaging) and used a high number of patients when making measurements to determine the length of the anterior loop. The Vaujanovic-Eskenazi study, although showing a substantial 12% difference in identification of the anterior loop of the alveolar nerve, did not achieve statistically significant results; however, the study directly compared CBCT to panoramic imaging using close to 100 subjects.
Perspective: The importance of these studies is directly related to the consequences of not accurately planning for implant placement; mainly, the risk associated with severing the alveolar nerve and associated vascular structures. Furthermore, if only panoramic images are to be used, a substantial hindrance in accuracy and prosthodontic placement must be compromised for by use of over-conservative safety margins (6 mm anterior to panoramic mental-foramen identification).
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| Applicability |
In light of the facts that (1) nearly 70% of patients have an anterior extension of the alveolar nerve and (2) it has been shown that panoramic imaging is inferior at identifying this as such compared to CBCT, the potential benefits (less risk of paresthesia and increased prosthodontic flexibility in terms of favorable biomechanical proportions) of proper identification of the alveolar nerve loop in patients receiving implants far outweigh the ALARA concerns a patient might have. |
| Specialty/Discipline |
(Oral Medicine/Pathology/Radiology) (General Dentistry) (Oral Surgery) |
| Keywords |
alveolar nerve, anterior loop, CBCT, and panoramic radiography
|
| ID# |
3115 |
| Date of submission: |
11/21/2016 |
| E-mail |
kats@livemail.uthscsa.edu |
| Author |
Joshua Kats, DDS |
| Co-author(s) |
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| Co-author(s) e-mail |
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| Faculty mentor/Co-author |
S. Thomas Deahl, II, DMD, PhD |
| Faculty mentor/Co-author e-mail |
deahl@uthscsa.edu |
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?) |
post a rationale |
| None available | |
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Comments and Evidence-Based Updates on the CAT
(FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) |
post a comment |
| None available | |
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