A clinical and anatomical study of the location of the mental foramen in adult Chinese mandibles

A New Transoral Vestibulum Single Incision Endoscopic-Assisted Thyroidectomy with Gasless

OBJECTIVE

We developed a novel method for thyroidectomy using a single-incision oral vestibular approach. To assess its advantages and disadvantages, we compared the perioperative parameters of this approach with those of transoral three-incision thyroidectomy and trans-areolar thyroidectomy.

METHODS

In a study of 136 papillary thyroid carcinoma patients (2016-2018), precise thyroidectomy and neck dissection were conducted. Among them, 52 chose single-incision oral vestibular approach, 33 chose three-incision variant, and 51 underwent trans-areolar thyroidectomy. Perioperative aspects of the transoral single-incision group were compared with those of transoral three-incision group, and transthoracic group.

RESULTS

In the cohort, meticulous tumor level VI lymph node dissection was performed, achieving intended resection extent with one case requiring a switch from transoral to transthoracic approach. No nerve palsy occurred in the transoral group. Thyroidectomy duration varied significantly across groups. Transoral single-incision had a shorter duration than transoral three-incision and longer than transthoracic. Minor differences were observed in blood loss and drainage. Perioperative factors like hematoma, infection, hypocalcemia, et al., remained consistent. Notably, no tumor recurrence was observed in this study.

CONCLUSIONS

This new transoral video-assisted neck surgery (TOVANS) method for thyroidectomy without gas insufflation approach did not increase the surgical complexity compared with the transoral vestibular three-incision thyroidectomy and the trans-areolar thyroidectomy.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:2976-2984, 2024.

Morphometric Development of the Mandible in Fetal Cadavers

PURPOSE

The aim of this study is to present reliable data by measuring the morphometric properties of the mandible in the fetal period.

METHODS

A study was performed on mandibles of 35 fetuses (18 male fetuses and 17 female fetuses), aged between 21 and 40 weeks of gestation. Fetuses were examined in 3 groups according to their developmental stages: 2nd trimester, 3rd trimester, and full-term. Morphometric measurements were performed for both the right and left sides of each mandible. The measurements of the mental foramen were performed using a digital caliper, and other measurements were performed using the ImageJ program. The data obtained were analyzed using the SPSS 20 for Windows program.

RESULTS

There was no significant gender difference for all parameters. When the parameters were compared by the trimesters, no significant difference was determined in the 2nd trimester - 3rd trimester, 3rd trimester-full-term, and second trimester - full-term comparisons of the angle of the mandible, and there was a significant difference in all other parameters (P < 0.05). According to the trimesters, all parameters, except the angle of the mandible, increased naturally with the development of the mandible. It was observed that the angle of the mandible decreased from the 2nd trimester to the 3rd trimester and increased from the 3rd trimester to the full term. When the right and left measurements were compared, no significant difference was found for all parameters in both general and trimester groups.

CONCLUSION

The present study includes fetal mandibular parameters that have not been reported elsewhere. It is thought that the obtained data will contribute to the determination of anomalies, pathologies, and variations.

Evaluation of Size and Location of a Mental Foramen in the Polish Population Using Cone-Beam Computed Tomography

Introduction

The mental foramen (MF) is a bilateral opening localized on an anterior surface of the mandible. A precise location as well as well-defined shape, size, and number of the MF is crucial for different clinical dental procedures. The aim of this study was to determine a size and location of the MF in relation to the lower teeth using the cone-beam computed tomography (CBCT) study.

Material and Methods

In a group of 201 patients (106 males and 95 females) the CBCT images were performed using the GX CB-500 device (Gendex, USA).

Results

No significant differences in values of the horizontal (H) and vertical (V) diameters as well as the H:V ratio on both sides in relation to the age of participants were found. In males both average values of a horizontal diameter (p=0.031) and vertical diameter (p=0.001) were significantly higher on the right side than in the female subgroup, whereas on the left side only an average value of a vertical diameter was significantly higher in men (p=0.006) in comparison to women. Moreover, the H:V ratio was significantly lower in males on the left side (p=0.032). There were no significant relationships between age and gender of the patients (p>0.05) and the type of mental foramen on the right and left sides.

Conclusions

The application of the CBCT study enabled a precise determination of the shape, size, and position of the mental foramen in relation to the neighboring anatomical structures on a representative group of the Polish patients. The results obtained may contribute to guidelines for dental procedures including anesthesia of the mental nerve and endodontic, implantology, and dental surgery with regard to the location of mental foramen depending on the sex and age of patients.

The mental foramen: A cone beam CT study of the horizontal location, size and sexual dimorphism amongst living Jordanians

Accurate information regarding the horizontal location and size of mental foramen (MF) has a well-known clinical importance. In addition, these variables have been reported to exhibit inter-population variation. The aims of the present study were to study the horizontal position and size of MF, as seen on cone beam CT (CBCT) images, and to assess sexual dimorphism in these variables. Total of 139 CBCT images of a random Jordanian sample (50 males, 89 females, average age = 43.5, SD = 13.0, range = 23-69 years) were included. The most frequent horizontal locations of MF were found to be: between the two lower premolars (50%), and in line with lower second premolar (40%). The average long diameter of MF was 3.08 mm, SD = 0.65 mm in males (n = 50, range = 1.5-4.8 mm) and 2.46 mm, SD = 0.58 mm in females (n = 89, range = 1.2-4.0 mm), and the difference was statistically significant. Very weak positive correlation was found between age and MF diameter in females (r = 0.161) and the correlation was approaching statistical significance (p-value = 0.066), while a weak negative correlation was found between these two variables in males (r = -0.276) and the correlation was statistically significant (p-value = 0.038). It could be inferred from the results of the present study that about 95% success rate for mental nerve block anesthesia is expected when the anesthetic solution is administered between the two premolars; however this needs to be tested experimentally. It appears that there is a tendency for an increase in MF size with age in females as opposed to a tendency for size reduction with age in males; this might suggest a role for sexual hormones in influencing MF size.

3D CBCT morphometric assessment of mental foramen in Arabic population and global comparison: imperative for invasive and non-invasive procedures in mandible

BACKGROUND

Recent advancements in clinical dentistry have increased the possibilities of surgical procedures in the mental region. A detailed knowledge of mental foramen (MF) morphometry is significant to preserve integrity of the mental nerve trunk in surgical interventions such as orthognathic surgery, implant placement and anaesthetic block.

OBJECTIVE

The aim of this study was to determine the most accurate position of the mental foramen by using new assessment approach in a sample of dental patients presenting to the specialist dental clinic, College of Dentistry, Al Jouf University, Saudi Arabia.

STUDY DESIGN

A retrospective study was performed using cone beam computed tomography (CBCT) of 600 patients (40.1 ± 11.78 years old). Following inclusion and exclusion criteria, 395 CBCT were finally obtained and analyzed for the most accurate position of the mental foramen (MF) by OnDemand 3D software (Seoul, Korea). Prevalence of shape of MF and accessory MF were also assessed. Pearson chi-square test was employed to test significant differences between genders and races.

RESULTS

The most common horizontal and vertical position of the mental foramen was in line with the long axis of 2nd premolar (41.3%) and below the root apex level (93.2%), respectively. The most common shape of MF was round type (72.66%). The prevalence of accessory 2MF and 3MF was 2.28% and 0.25%, respectively.

CONCLUSION

New information about MF presented in this article can help anatomists, prosthodontists, orthodontists, surgeons, forensic odontologists and paleoanthropologists to predict the position of the MF and perform safer surgeries.

Assessment of the Mental Foramen Location in a Sample of Fully Dentate Lebanese Adults Using Cone-beam Computed Tomography Technology

Objective:

The literature reports that the location of mental foramen shows differences among races. The aim of this study was to assess the mental foramen position in a sample of Lebanese population using cone-beam computed tomography (CBCT) technology.

Materials and methods:

In this study, we investigated CBCT images of 50 fully dentate Lebanese adults (23 males and 27 females). We assessed the horizontal position of the mental foramen in relation with the mandibular premolars in both right and left sides and the vertical position by measuring the distance from the upper border of the foramen to the inferior border of the body of the mandible. The data obtained were statistically analyzed using Chi-square test, and two-sided t-test. Statistical significance was set at p < 0.05.

Results:

In our sample, the mental foramen was mostly found in line with the second mandibular premolar in both sides and the mean distance from the superior border of the foramen to the inferior border of the body of the mandible was 13.0120 ± 0.98487 mm on the right and 13.0728 ± 0.96029 mm on the left.

Conclusion:

Within the limits of this study, we concluded that in our sample of Lebanese population, there was substantial variability in the mental foramen location.

Using drill stops on twist drills to promote safety and efficiency when creating osteotomies for dental implants

BACKGROUND

A growing number of dental implants are being placed each year in the United States. This upward trend is associated with an increased incidence of comorbidities. In this regard, use of a drill stop has the potential to decrease unintended consequences of overdrilling the depth of an osteotomy.

METHODS

The authors did not find any studies in the dental literature in which researchers assessed the safety and effectiveness of using drill stops on twist drills. Nevertheless, the advantages of utilizing drill stops and the undesired results due to excessive drilling can be reasonably deduced.

RESULTS

The authors describe the following clinically relevant issues pertaining to overdrilling of osteotomies for dental implants: the anatomical effect of excessive drilling in different sections of the oral cavity, reasons for excessive drilling, methods to avoid overlengthening of implant sites and benefits of using drill stops on twist drills.

CONCLUSIONS

Use of drill stops enhances safety, accuracy and efficiency when creating an osteotomy. Drill stops also reduce the clinicians and patients stress during operative procedures.

PRACTICAL IMPLICATIONS

Drills stops can be beneficial when utilized in situations in which there is reduced visibility, making it difficult to read the lines on a twist drill. They also are helpful when there is a dearth of bone over the mandibular or mental nerves, and precisely lengthened osteotomies are needed to avoid nerve injuries.

The surgical relevance of the anatomic position of the extraosseous mental nerve in a Kenyan population

INTRODUCTION

Precise location of the mental nerve is important in implant surgery, administration of mental nerve block anaesthesia, and for osteotomy procedures. The position is known to show inter-population differences but data from sub-saharan region is scarce.

METHODS

The point of emergence of 64 nerves was studied and data analyzed with Microsoft Excel 2010 and differences in side means compared using the paired one tailed student's t test.

RESULTS

The location of left mental nerve was 2.85 (±0.38) cm, 1.42 (±0.33) cm, 1.77 (±0.46) cm while the right was 2.91(±0.47) cm, 1.38 (±0.3.1) cm, 1.71 (±0.46) cm from the mental symphysis, inferior border of mandible and cemento-enamel junction respectively. The differences in position between the right and left sides were not statistically significant (p<0.05 CI: 95%). It emerged inferior to but in line with the 2nd premolar in 57.8% of the cases, 2nd premolar-1st molar (25%) and inter-premolar junction (9.4%). Unique to this study, was the location of the MN at the canine (3.1%), and 1st molar (4.7%) positions.

CONCLUSION

The aberrant position of the mental nerve seen in 42%, is an important consideration for tooth implants and placement of mandibular reconstruction plates.

Radiographic localization of mental foramen in Northeast and South Indian ethnic groups of Indian population

BACKGROUND AND OBJECTIVES

The position of mental foramen varies in different ethnic groups. The position of mental foramen is mainly important for achieving effective mental nerve block to carry out dental surgical procedures in mandible. Deviation in its position can be a cause of complication during local anesthesia or surgical procedures. The position of the mental foramen in South Indian and Northeast Indian population has not been reported. The purpose of the current study was to determine the most common location of the mental foramen (MF) and its bilateral symmetry in selected Indian population.

MATERIALS AND METHODS

380 digital panoramic radiographs (DPR) of a randomly selected 2 Ethnic groups of Indian population were studied.

RESULTS

The common position (59.2%) of the mental foramen was located between the 1st and 2nd premolars (P3) in Northeast Indians and in South Indians the common location (62.8%) was in line with the long axis of the 2nd premolar (P4), which was statistically significant in both Populations.

CONCLUSION

A bilateral symmetry was observed in the location of mental foramina, either mesial to or in line with the long axis of the 2nd premolar, which is consistent with the observations of similar studies in various ethnic or racial groups. In our study a statistically significant association between the 2 ethnic groups and the position of mental foramen exists. Therefore the position of mental foramen may be specific to racial groups facilitating accurate landmark for mental nerve block depending on the ethnic group. Further, studies are required with larger sample for better understanding of mental foramen location in different ethnic groups.

Morphometric and morphologic evaluation of the mental foramen in relation to age and sex: an anatomic cone beam computed tomography study

OBJECTIVE

The aim of this study was to assess the vertical and horizontal position, angle, and diameter of the mental foramen (MF) according to sex and age by cone beam computed tomography in a Turkish patient population.

METHODS

Cone beam computed tomography records of 192 consecutive patients consisting of 106 women and 86 men were examined, retrospectively. The vertical and horizontal positions of MF, angle and diameter of MF, and distance from MF to the alveolar crest and the base of the mandible were evaluated with respect to sex and age groups.

RESULTS

There were statistically significant differences in the distance of MF to the alveolar crest according to age groups. When we compared the right and left sides, we have only found out statistically significant differences in the angles of MF and that it was higher in the left side.

CONCLUSIONS

From our results, the detection of the position of MF can provide detailed information for preoperative treatment planning (for surgery and dental implant surgery procedures), especially in the mandibular premolar region.

Anthropometrics of mental foramen in dry dentate and edentulous mandibles in Coastal Andhra population of Andhra Pradesh State

AIM

The aim of this study is to determine the morphological features and morphometrics of mental foramen with reference to surrounding anatomical landmarks in Coastal Andhra population of Andhra Pradesh State.

MATERIALS AND METHODS

Two-hundred and nineteen dry dentate and edentulous mandibles are examined in this study. Out of these 127 were dentate and 92 were edentulous. Various morphological and morphometrical parameters were measured by using digital Vernier caliper, metallic wire and metallic scale on both the right and left sides.

RESULTS

In the present study, the distance between most anterior margin of mental foramen and posterior border of ramus of the mandible is [MF-PR], MF-PR is 69.61 ± 6.03 mm on the right side and is 69.17 ± 6. 0 mm on left side in dentate mandible. In edentulous type, MF-PR is 68.39 ±6.4 mm on right side and 68.81 ± 6.55 mm on left side. In the present study, the distance between symphysis menti and most anterior margin of mental foramen [MF-SM] in dentate mandible is 28.24 ± 5.09 mm on right side and is 27.45 ± 3.7 mm on left side. In edentulous mandible (MF-SM) is 28.51 ± 4.5 mm on right side and on left side is 27.99 ± 4.50 mm.

CONCLUSION

Acquiring the knowledge and importance of anatomy of mental foramen is helpful in avoiding neurovascular complications, during regional anesthesia, peri apical surgeries, nerve repositioning and dental implant placement.

Computed tomographic analysis of the mental foramen and nerve in Japanese patients

PURPOSE

The aims of this study were to investigate the anatomical features of the mental foramen in Japanese patients through computed tomography (CT) imaging to reduce inadvertent damage to the mental nerve during implant placement.

MATERIALS AND METHODS

The mandibles of 100 patients were observed on CT imaging. The location, shape, number, and size of the mental foramen were evaluated. Furthermore, the vertical and horizontal dimensions of the anterior loops were measured.

RESULTS

The mental foramen was mainly located by the apex of the second mandibular premolar in male, whereas the mental foramen was mainly located by the apex of the second mandibular premolar and between the apex of the second premolar and the first mandibular molar in female. With exception of a few hemi-mandibles, its shape was oval and the number of the mental foramen was 1. There was no significant difference in the size of the mental foramen between male and female. There was a significant difference in the vertical dimension of the anterior loops between the males and females.

CONCLUSION

In general, altered lip sensations are preventable if the mental foramen is located, and this knowledge is employed when performing surgical procedures in the foraminal area.

Identification of the mandibular vital structures: practical clinical applications of anatomy and radiological examination methods

Objectives

The purpose of this article was to review the current available clinical techniques and to recommend the most appropriate imaging modalities for the identification of mandibular vital structures when planning for oral implants.

Material and Methods

The literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were mandibular canal, mandibular incisive canal, mental foramen, anterior loop of the mental nerve, radiography, dental implants. The search was restricted to English language articles, published from January 1976 to January 2010.

Results

In total 111 literature sources were obtained and reviewed. The peculiarities of the clinical anatomy of mandibular canal, mandibular incisive canal, mental foramen and anterior loop of mental nerve were discussed. Radiological diagnostic methods currently available for the identification of the mandibular vital structures when planning for oral implants were presented. Guidelines for the identification of the mandibular vital structures in dental implantology were made.

Conclusions

The proposed guideline provides clinicians a tool in proper identifying the important mandibular vital structures thus minimizing the potential complications during implant surgery.

Effect of ageing towards location and visibility of mental foramen on panoramic radiographs

Mental foramen is an opening of the mental canal onto the lateral surface of the mandible. In this pilot radiographical study, in Malay population the effects of ageing towards the location and visibility of the mental foramen were determined. Most of the mental foramina were found to be located inferior to the apex of the second premolar. Non-visibility of the foramen was greatly increased in patients aged 50 years and above (Pearson Chi-square; p = 0.00). This finding may provide a guide to dental surgeries in Malay patients of different age groups.

Atypical trigeminal neuralgia of the mental nerve: a case study

Any division or branch of the trigeminal nerve can exhibit signs and symptoms of neuralgia. Those who treat patients suffering with craniofacial pain are frequently charged with determining the cause of illusive pain complaints and if objective signs are not discovered, the patient may not be treated and may be forced to seek help elsewhere. Trigeminal neuralgia-like pain is often seen in the mental nerve region of the mandible, but frequently, there is no radiographic evidence for the source of such pain. In the current case report, it was discovered that the patient's mental nerve pain was cause by an irregular surface of the anterior portion of the mental foramen. Successful treatment was provided by surgically recontouring the edge or lip of the mental foramen without injury to the mental nerve.

Position of the mental foramen in a northern regional Jordanian population

BACKGROUND

The mental foramen is frequently encountered in a number of maxillofacial surgical procedures. Its position has been shown to vary according to race. The aim was to study the position, shape, and appearance of the mental foramen, as seen on panoramic radiographs of Jordanians, and to compare our findings with international values.

PATIENTS AND METHODS

Panoramic radiographs were randomly selected from the records of dental patients attending three dental services, and were analyzed according to patients' age and gender, and the mental foramina's anterior-posterior and superior-inferior positions, shape, appearance, and symmetry.

RESULTS

There were 860 cases (1,720 sides) with a female-to-male ratio of 1:1.4, and mean age of 24. The most frequent anterior-posterior position was in the area between the long axes of first and second mandibular premolar teeth. With advancing age, there was an increase in the frequency of more posterior positioning. The anterior-posterior position was asymmetrical in 33% of cases. The most frequent superior-inferior position was below the level of apices of mandibular premolar teeth roots. With advancing age there was an increase in the frequency of more inferior positioning. The superior-inferior position was asymmetrical in 14% of cases. The majority of foramina were round in shape, and the most frequent appearance was the continuous type. Accessory mental foramina were seen in 10% of the cases.

CONCLUSION

The position of the mental foramen on panoramic radiographs in this selected group of Jordanians is most commonly below and between the mandibular premolar teeth, and the most frequent appearance was the continuous type. These results are similar to previous findings in Caucasian populations.

The Mental Foramen and Nerve: Clinical and Anatomical Factors Related to Dental Implant Placement: A Literature Review

BACKGROUND

The mental foramen is a strategically important landmark during osteotomy procedures. Its location and the possibility that an anterior loop of the mental nerve may be present mesial to the mental foramen needs to be considered before implant surgery to avoid mental nerve injury.

METHODS

Articles that addressed the position, number, and size of the mental foramen, mental nerve anatomy, and consequences of nerve damage were evaluated for information pertinent to clinicians performing implant dentistry.

RESULTS

The mental foramen may be oval or round and is usually located apical to the second mandibular premolar or between apices of the premolars. However, its location can vary from the mandibular canine to the first molar. The foramen may not appear on conventional radiographs, and linear measurements need to be adjusted to account for radiographic distortion. Computerized tomography (CT) scans are more accurate for detecting the mental foramen than conventional radiographs. There are discrepancies between studies regarding the prevalence and length of the loop of the mental nerve mesial to the mental foramen. Furthermore, investigations that compared radiographic and cadaveric dissection data with respect to identifying the anterior loop reported that radiographic assessments result in a high percentage of false-positive and -negatives findings. Sensory dysfunction due to nerve damage in the foraminal area can occur if the inferior alveolar or mental nerve is damaged during preparation of an osteotomy.

CONCLUSIONS

To avoid nerve injury during surgery in the foraminal area, guidelines were developed based on the literature with respect to verifying the position of the mental foramen and validating the presence of an anterior loop of the mental nerve. These guidelines included leaving a 2 mm zone of safety between an implant and the coronal aspect of the nerve; observation of the inferior alveolar nerve and mental foramen on panoramic and periapical films prior to implant placement; use of CT scans when these techniques do not provide clarity with respect to the position of the nerve; surgical corroboration of the mental foramen's position when an anterior loop of the mental foramen is suspected of being present or if it is unclear how much bone is present coronal to the foramen to establish a zone of safety (in millimeters) for implant placement; once a safety zone is identified, implants can be placed anterior to, posterior to, or above the mental foramen; and prior to placing an implant anterior to the mental foramen that is deeper than the safety zone, the foramen must be probed to exclude the possibility that an anterior loop is present. In general, altered lip sensations are preventable if the mental foramen is located and this knowledge is employed when performing surgical procedures in the foraminal area.

Mental foramen in Thais: an anatomical variation related to gender and side

Sixty-nine adult mandibles (45 male, 24 female) of Thai dry skulls were assessed to determine the size, the orientation and the location of the mental foramen (MF) related to gender and side. The results showed that the usual direction of exit of the MF was in a posterosuperior direction. The most common location of the MF was bilaterally symmetrical and located on the same vertical line with the long axis of the lower second premolar. The mean distances from the MF to the symphysis menti (A), to the posterior border of the mandibular ramus (P), to the lower border of the mandible (mb) and to the buccal cusp tip of the second premolar (cm) were 28.83, 68.85, 14.88 and 24.27 mm, respectively. The mean distances from the alveolar bone crest across the MF to the lower border of the mandible (ab) was 29.97 mm. The mean distance from the buccal cusp tip of the second premolar through the long axis of the clinical crown to the lower border of the mandible (cb) was 39.18 mm. No measurements varied according to the sides (P > 0.05). In contrast, gender differences were significant in all measurements with the longer distances in males (P < 0.05). The mean ratios of A/(A + P), mb/ab and cm/cb in all subjects were 0.30, 0.50 and 0.62, respectively. The values of the three ratios were nearly equal in males and females. Our results may assist surgeons to localize important maxillofacial neurovascular bundles passing through the MF in avoiding complication from local anesthetic, surgical and other invasive procedures.

Position of the Mental Foramen in a Korean Population: A Clinical and Radiographic Study

PURPOSE

The purpose of this study was to improve the treatment methods for the mental foramen by comparing the directly measured values with the radiographic measured values.

MATERIALS AND METHODS

One hundred and twelve mental foramina (72 males, 40 females) that were exposed during the operation were examined. The patients' age ranged from 12 to 69 years, with a mean age of 41.8 years. All patients had fully erupted lower premolars. The horizontal and vertical locations were evaluated with both direct and radiographic measurements.

RESULTS

In 72 patients (64.3%), the mental foramen was below the second premolar. In 26.8%, it was between the first and second premolar, and in 8.9%, it was below the first premolar. By radiographic readings,most of the mental foramina were found to be below the second premolar (62.5%). The average distance between the cusp tip and the superior border of the mental foramen by direct measurement was 23.42 mm and 25.69 mm in the panoramic view. The mean distance between the superior border of the mental foramen and the bottom of the mandible was 14.33 mm by direct measurement and 16.52 mm by radiographic measurements.

CONCLUSION

It is important to know the position of the mental foramen for the placement of osseointegrated implants in the mandibular premolar region. The position of the mental foramen of Koreans is closer to the cusp tips of lower premolars than Westerners.

Anatomical variations of the supraorbital, infraorbital, and mental foramina related to gender and side

PURPOSE

The aim of the study was to examine the different anatomical variations of the supraorbital, infraorbital, and mental foramina related to gender and side.

MATERIALS AND METHODS

Measurements were made on 110 adult skulls without mandibles and isolated mandibles. Gender was determined for each skull. Parameters measured bilaterally included the distances from the supraorbital and mental foramina to midline, from the infraorbital foramen to the anterior nasal spine, from the infraorbital foramen to the inferior orbital rim, and from the mental foramen to the inferior rim of the mandible and the angle between the line linking the infraorbital foramen with the anterior nasal spine and horizontal plane. Comparisons were made between genders and sides and statistical analysis was done where appropriate using Student's t test.

RESULTS

There were 70 male and 40 female crania. Nature of the 3 foramina was similar between sides and genders. The average distance from the left supraorbital foramen to midline in females was significantly lower than that in males (2.42+/-0.04 versus 2.56+/-0.05). The mean distances from the bilateral infraorbital foramina to anterior nasal spine in females were also significantly lower relative to those in males (3.28+/-0.03 versus 3.48+/-0.03 right and 3.31+/-0.03 versus 3.50+/-0.03 left). There were also considerable differences between sides in the average angle of the infraorbital foramen in both genders.

CONCLUSIONS

Differences in several measurements suggest that gender and side should be considered when applying the anatomical variation data to an individual subject.

Morphometric Analysis of Implant-Related Anatomy in Caucasian Skulls

BACKGROUND

Sequelae related to implant placement/advanced bone grafting procedures are a result of injury to surrounding anatomic structures. Damage may not necessarily lead to implant failure; however, it is the most common cause of legal action against the practitioner. This study aimed to describe morphological aspects and variations of the anatomy directly related to implant treatment.

METHODS

Morphometric analyses were performed in 22 Caucasian skulls. Measurements of the mental foramen (MF) included height (MF-H), width (MF-W), and location in relation to other known anatomical landmarks. Presence or absence of anterior loops (AL) of the inferior alveolar nerve (IAN) was determined, and the mesial extent of the loop was measured. Additional measurements included height (G-H), width (G-W), thickness (G-T), and volume (G-V) of monocortical onlay grafts harvested from the mandibular symphysis area, and thickness of the lateral wall (T-LW) of the maxillary sinus. The independent samples t test, and a two-tailed t test with equal variance were utilized to determine statistical significance to a level of P < 0.05. Multiple regression analyses were performed to determine if each one of these measurements was affected by age and gender.

RESULTS

The most common location of the MF in relation to teeth was found to be below the apices of mandibular premolars. The mean MF-H was 3.47 +/- 0.71 mm and the mean MF-W was 3.59 +/- 0.8 mm. The mean distance from the MF to other anatomical landmarks were: MF-CEJ = 15.52 +/- 2.37 mm, MF to the most apical portion of the lower cortex of the mandible = 12.0 +/- 1.67 mm, MF to the midline = 27.61+/- 2.29 mm, and MF-MF = 55.23 +/- 5.34 mm. A high prevalence of AL was found (88%); symmetric occurrence was a common finding (76.2%), with a mean length of 4.13 +/- 2.04 mm. The mean size of symphyseal grafts was: G-H = 9.45 +/- 1.08 mm, G-W = 14.5 +/- 3.0 mm, and G-T = 6.15 +/- 1.04 mm, with an average G-V of 857.55 +/- 283.97 mm3 (range: 352 to 1,200 mm3). The mean T-LW of the maxillary sinus was 0.91 +/- 0.43 mm.

CONCLUSION

Implant-related anatomy must be carefully evaluated before treatment due to considerable variations among individuals, in order to prevent injury to surrounding anatomical structures and possible damage.