Accessory mandibular foramina: Histological and immunohistochemical studies of their contents

Morphological alterations in the position of the mandibular foramen in dentate and edentate mandibles

The technique of inferior alveolar nerve (IAN) block must be based on precise anatomical knowledge regarding the correct position of the mandibular foramen (MF). The aim of the investigation reported here was to determine the anatomic and topographic localization of the MF according to mandibular ramus anatomic landmarks and to identify morphological alterations in the position of the MF and size and shape of the ramus in terms of the impact of tooth socket loss in the molar and premolar region. Seventy-three dry human adult mandibles were divided into two groups according to dental status. These were measured to determine the distances from the anterior and posterior ramus border (AB, PB) to the midpoint of the MF fossa, and from the mandibular notch (MN) and inferior ramus border (IB) to the MF entering point. A number of relevant ramus anatomic features were analyzed, such as ramus width (RW), height (RH), and thickness (RT). The MF was closer to the PB and IB in edentate mandibles (right/left mean PB-MF 10.66 ± 1.84/11.06 ± 2.05 mm; right/left mean IB-MF 21.77 ± 3.23/21.8 ± 2.27 mm) compared to dentate mandibles (right/left mean PB-MF 11.87 ± 2.08/12.04 ± 1.94 mm; right/left mean IB-MF 22.94 ± 3.09/22.74 ± 3.74 mm). Edentate mandibles demonstrated reduced RW (right/left mean RW 26.03 ± 3.53/26.49 ± 3.90 mm), significantly reduced (p = 0.03) right RH (right/left mean RH 43.56 ± 4.74/45.43 ± 4.86 mm), and significantly reduced (p < 0.05) RT in the area of the MF fossa depression (right/left mean RT 5.52 ± 1.21/5.21 ± 0.91 mm) compared to dentate mandibles (right/left mean RW 27.34 ± 3.84/27.48 ± 3.80 mm; right/left mean RH 46.33 ± 4.52/47.40 ± 4.20 mm; right/left mean RT 7.86 ± 1.98/8.10 ± 1.92 mm). Alterations in MF position and mandibular ramus anatomic features in edentate mandibles increase the potential risk of complications and failure of IAN block.

Number of accessory or nutrient canals in the human mandible

OBJECTIVES

The aim of the study was to assess the presence, location and the number of accessory or nutrient canals in the body of the mandible by means of cone beam CT images, obtained with the Planmeca ProMax® 3D Max device.

MATERIAL AND METHODS

Seventy-four cone beam images of the mandible from adult patients (37 males and 37 females) who were imaged for dental implantology planning or third molar extraction were used to assess the number and location of accessory or nutrient canals. All images were taken with the same machine (Planmeca® ProMax 3D Max) at 200-, 400- or 600-μm resolution. Distinction was made between canals entering or exiting the mandible superior or inferior of the inferior alveolar canal and between similar canals superior or inferior of the genial tubercula.

RESULTS

The number of accessory canals varied between nil to 11. No statistical significant difference between males and females was found with regard to the number or location of accessory canals in the mandible. Only 5.4% of patients had no accessory canals. One to five accessory canals were found in 71.6%, and 23% of patients had more than five accessory canals. The majority (81%) of patients had between two and six accessory canals.

CONCLUSION

It seems that subjects showing no accessory canals whatsoever should be considered exceptional as more subjects with than without accessory canals in the body of the mandible were found.

CLINICAL RELEVANCE

These results are clinically relevant for mandibular surgery and mandibular local anaesthesia.

Anatomical classification of accessory foramina in human mandibles of adults, infants, and fetuses

In the past few decades, a number of studies have reported that accessory foramina are located on the internal aspect of the mandible, indicating their potential importance for effective and successful clinical procedures. The aim of this study is to evaluate adult, infantile, and fetal human mandibles for occurrence of accessory foramina. To our knowledge, this is the first time that an attempt has been made to examine their particular co-location using a systematic approach and perspective. A total of 397 human mandibles, including 299 adult, 18 infantile, and 80 fetal, were investigated macroscopically for the frequency, position, and diameter of accessory foramina. In 96 % of investigated adult mandibles, at least one accessory foramen was found. Foramina were located either superior or inferior to the genial tubercle, as well as lateral to the tubercle. Bearing in mind their usual location, four different types of coexistence of foramina were distinguished. Accessory foramina were also present in similar locations in infantile and fetal mandibles. Accessory mandibular foramina are constant structures of human mandible. Their frequency, size, and location vary depending on the type of the foramen. Observations on children and fetal mandibles showed no significant differences in evaluation of accessory foramina, with the exception of lower occurrence in this group of subjects.

A review of the mandibular and maxillary nerve supplies and their clinical relevance

Mandibular and maxillary nerve supplies are described in most anatomy textbooks. Nevertheless, several anatomical variations can be found and some of them are clinically relevant. Several studies have described the anatomical variations of the branching pattern of the trigeminal nerve in great detail. The aim of this review is to collect data from the literature and gives a detailed description of the innervation of the mandible and maxilla. We carried out a search of studies published in PubMed up to 2011, including clinical, anatomical and radiological studies. This paper gives an overview of the main anatomical variations of the maxillary and mandibular nerve supplies, describing the anatomical variations that should be considered by the clinicians to understand pathological situations better and to avoid complications associated with anaesthesia and surgical procedures.

Area of Desensitization following Mental Nerve Block in Dogs

Regional nerve blocks are commonly used to provide analgesia for dental and oral surgical procedures. The purpose of this study was to demarcate the areas of the mandible that would be desensitized by application of the mental nerve block. Seven healthy mixed-breed dogs were anesthetized for an annual dental examination and professional teeth cleaning procedure. Bupivacaine HCl (0.4 ml/m2) was administered at one middle mental foramen based on previously described techniques for the mental nerve block. A noxious stimulus was applied at 23 predetermined ipsilateral mandibular locations using pressure from a mosquito hemostat on the mucocutaneous junction (MCJ) and a dental curette on the vestibular mucogingival line (MGL) at the incisor, canine, and premolar teeth; and, the mesial and distal aspects of the first molar tooth. A thermal stimulus using a refrigerant spray on a cotton ball was applied to the ipsilateral canine, third premolar, and fourth premolar teeth; and, the mesial and distal aspects of the first molar tooth. Demonstration of nociception or anesthesia was noted and the responses tabulated. The area of desensitized tissues was smaller than expected and highly variable within the study group. In conclusion, the unilateral mental nerve block does not reliably provide generalized desensitization to tissues of the incisive and rostral regions of the mandible. Although the mental nerve block is recommended, other modes of analgesia should be emphasized for surgical and dental procedures involving these areas.