Mandibular cortical indices and their relation to gender and age in the cone-beam computed tomography

How geographical origin and dietary habits interact with the shape of cortical mandibular sections? A geometric morphometrics study in an archaeological context

OBJECTIVE

Mandibular shape is strongly influenced by biomechanics, particularly during dietary shifts that often occurred in past populations. The relationship is considered extremely complex as development of the mandible is a multifactorial process. Since cortical bone distribution is purportedly more biomechanically sensitive than external shape, comparison of its distribution in past populations can provide new input to understand this complex relationship. The present study examined the effects of geographical origin and dietary habits on the internal anatomy of the mandibular corpus and symphysis.

DESIGN

A morphometric analysis was conducted on 72 mandibles from different populations, sampled by their geographical origin and subsistence strategies. Procrustes ANOVAs were performed to test the impact of section-plane location, geographical origin, and dietary habits on the groups' shapes.

RESULTS

The specimens' geographical origin and dietary habits had a significant effect on the shapes of the sections (Generalized Goodall F-test, F = 3.2745, df = 6, 304: p < 0.001 and F = 3.7007, df = 4, 306: p < 0.001).

CONCLUSION

Geographical origin and dietary habits influenced the shape of the mandibular sections in our sample. These relationships become more complex when analysed in isolated sections. Indeed, this study revealed that symphysis sections could be predominantly influenced by individual variables, whereas intermediate sections of the corpus could be predominantly influenced by populational variables. Future studies could focus on specific sections to better identify the specific "rules of dependence" in each cross-section.

Evaluation of mandibular cortical and trabecular radiomorphometry in familial Mediterranean fever patients

OBJECTIVE

The objective of this retrospective study was to evaluate the mandibular cortical and trabecular morphology and microarchitecture of patients with familial Mediterranean fever (FMF) and compare them to those of healthy individuals by examining radiomorphometric indices on panoramic radiographs.

STUDY DESIGN

We examined a group of 56 FMF patients aged 5 to 71 years and an age- and sex-matched control group of individuals with no systemic diseases. We classified the FMF and control groups according to age and sex and the FMF group according to colchicine use. We evaluated the quantitative radiomorphometic indices of gonial index, antegonial index, molar cortical thickness, mental index, panoramic mandibular index, and lacunarity, and the qualitative mandibular cortical index on all panoramic radiographs and performed between and within group analysis.

RESULTS

Mean gonial index, antegonial index, and molar cortical thickness values of the FMF group were significantly smaller than those of the control group. Significantly fewer patients in the FMF group were classified as mandibular cortical index type 1 compared to the control group. There were no significant differences in quantitative index values according to colchicine use in the FMF group or regarding the categorical parameters of age, sex, and mandibular cortical index classification.

CONCLUSIONS

Radiomorphometric values of the mandibular basal cortex posterior to the mental foramen differ significantly in FMF patients compared to healthy counterparts. Dentists should note mandibular morphologic changes indicative of low bone density when examining panoramic images of patients with this disease.

Evaluation of Cortical Thicknesses and Bone Density Values of Mandibular Canal Borders and Coronal Site of Alveolar Crest

Objectives

The objectives of this retrospective study are to measure the amount of the alveolar crest cortication and cortication around the mandibular canal, and to evaluate bone density values of alveolar crest, cortication around mandibular canal, and possible implant placement area for edentulous sites.

Material and Methods

Six hundred forty-two cone-beam computed tomography scans from 642 subjects were evaluated in four centers. Cortical thicknesses of alveolar crest and mandibular canal cortical borders (buccal, lingual, apical, and coronal) in each mandibular posterior teeth region were measured. Bone density of alveolar crest and mandibular canal cortical borders (buccal, lingual, apical, and coronal) in each mandibular posterior teeth region were recorded. The correlations between numeric variables were investigated using Pearson's correlation test.

Results

The largest cortical border of the canal was measured 1.1 (SD 0.71) mm at the left second molar area and in coronal side of the mandibular canal (MC). Left and right first premolar regions showed higher bone density values compared to the other sites in all bone density values evaluations. The buccal side of the canal at the right first premolar region showed the highest bone density values (832.32 [SD 350.01]) while the coronal side of the canal at the left second molar region showed the lowest (508.75 [SD 225.47]). The bone density of possible implant placement area at the both left (692.25 [SD 238.25]) and right (604.43 [SD 240.92]) edentulous first premolar showed the highest values. Positive correlations between the bone density values of alveolar crest and the coronal side of MC were found in molar and left second premolar regions (P < 0.05).

Conclusions

Results may provide information about the amount of cortication and bone densities tooth by tooth for posterior mandible to surgeons for planning the treatment precisely.

Mandibular Radiomorphometric Characteristics of Individuals with Bilateral or Unilateral Cleft Lip and Palate

OBJECTIVE

This study aimed to investigate and compare the mandibular radiomorphometric characteristics of patients with unilateral or bilateral cleft lip and palate (CLP) with those of individuals without CLP and to determine whether there was a difference.

DESIGN

Retrospective cohort study.

SETTING

Orthodontic Department in Faculty of Dentistry.

PATIENTS AND INTERVENTIONS

Mandibular cortical bone thickness was measured on high-quality panoramic radiographs taken from 46 patients with unilateral or bilateral CLP aged 13-15 years and 21 control patients.

MAIN OUTCOME MEASURES

Three radiomorphometric indices [antegonial index (AI), mental index (MI), and panoramic mandibular index (PMI)] were measured bilaterally. AutoCAD software was used for MI, PMI, and AI measurements.

RESULTS

Left MI values were significantly lower in individuals with unilateral cleft lip and palate (UCLP; 0.029 ± 0.04) than in individuals with bilateral cleft lip and palate (BCLP; 0.033 ± 0.07). In addition, right MI values of individuals with right UCLP (0.26 ± 0.06) were significantly lower than those of individuals with left UCLP (0.34 ± 0.06) or BCLP (0.32 ± 0.08). No difference was observed between individuals with BCLP and left UCLP. These values did not differ between groups.

CONCLUSIONS

Antegonial index and PMI values did not differ between individuals with different types of CLP or when compared with control patients. In patients with UCLP, cortical bone thickness was found to be reduced on the cleft side compared to the intact side. Patients with UCLP with a right-sided cleft had a more substantial decrease in cortical bone thickness.

Assessment of Radiodensity at Mandibular Periapical Bone Sites using Three-Dimensional Cone-Beam Computed Tomography

Objectives

The aims of this retrospective study were to objectively assess bone density values obtained by cone-beam computed tomography and to map the periapical and inter-radicular regions of the mandibular bone.

Material and Methods

In total, periapical bone regions of 6898 roots scanned by cone-beam computed tomography were evaluated retrospectively, and the results were recorded using Hounsfield units (HU).

Results

The correlation between periapical HU values of adjacent mandibular teeth were strongly positive (P ˂ 0.01). The anterior region of the mandible yielded highest mean HU value (633.55). The mean periapical HU value of the premolar region (470.58) was higher than that was measured for molar region (374.58). The difference between furcation HU values of the first and second molars was unnoticeable.

Conclusions

The results of this study have tried to evaluate the periapical regions of all mandibular teeth, which could ease to predict the bone radiodensity before implant surgery. Even though the Hounsfield units provide the average radio-bone density, a site-specific bone tissue evaluation of each case is essential for appropriate cone-beam computed tomography preoperative planning.

The Radiological Evaluation of Mandibular Canal Related Variables in Mandibular Third Molar Region: a Retrospective Multicenter Study

OBJECTIVES

The aim of this retrospective study was to investigate anatomical structure of mandibular canal and the factors those increase the possibility of inferior alveolar nerve damage in mandibular third molar region of Turkish population.

MATERIAL AND METHODS

Overall 320 participants with 436 mandibular third molars were included from four different study centers. Following variables were measured: type and depth of third molar impaction, position of mandibular canal in relation to third molars, morphology of mandibular canal, cortication status of mandibular canal, possible contact between the third molars and mandibular canal, thickness and density of superior, buccal, and lingual mandibular canal wall, bucco-lingual and apico-coronal mandibular canal diameters on cone-beam computed tomography scans.

RESULTS

Lingual mandibular canal wall density and thickness were decreased significantly as the impaction depth of mandibular third molar was increased (P = 0.045, P = 0.001 respectively). Highest buccal mandibular canal wall density and thickness were observed in lingual position of mandibular canal in relation to mandibular third molar (P = 0.021, P = 0.034 respectively). Mandibular canal with oval/round morphology had higher apico-coronal diameter in comparison to tear drop and dumbbell morphologies (P = 0.018). Additionally, mandibular canals with observed cortication border and no contact with mandibular third molar had denser and thicker lingual mandibular canal wall (P = 0.003, P = 0.001 respectively).

CONCLUSIONS

Buccal and lingual mandibular canal wall density, thickness and mandibular canal diameter may be related with high-risk indicators of inferior alveolar nerve injury.

A computed tomography-based analysis of the structure of the mandible according to age and sex

Background

The primary objectives of mandibular surgery are to achieve optimal occlusion, low sensory disturbance, and adequate fixation with early movement. In-depth knowledge of the mandibular structure is required to achieve these goals. This study used computed tomography (CT) to evaluate the mandibular cortical thickness and cancellous space according to age and sex.

Methods

We enrolled 230 consecutive patients, aged 20 to 50 years, who underwent CT scanning. The cortex and cancellous space centered around the inferior alveolar nerve (IAN) canal were measured at two specific locations: the lingula and second molar region. Statistical analysis of differences according to increasing age and sex was performed.

Results

The t-test revealed that the cancellous space and cortical thickness differed significantly with respect to the threshold of 35 years of age. Both cortical thickness and cancellous space in the molar region were negatively correlated with age. Meanwhile, both cortical thickness and cancellous space in the lingula region showed a positive correlation with age. With respect to sex, significant differences in the cancellous space at the molar region and the cortical thickness at the lingula were observed. However, no further statistically significant differences were observed in other variables with respect to sex. The sum of each measurement on the mandibular body reflected the safe distance from the surface of the outer cortex to the IAN canal. The safe distances also showed statistically significant differences between those above and below 35 years of age.

Conclusion

Knowledge of the anatomical structure of the mandible and of changes in bone structure is crucial to ensure optimal surgical outcomes and avoid damage to the IAN. CT examination is useful to identify changes in the bone structure, and these should be taken into account in the planning of surgery for older patients.

Association between ridge morphology and complexity of implant placement planning in the posterior mandible

STATEMENT OF PROBLEM

Uncertainties regarding the 3D ridge morphology of the posterior mandible can greatly increase the risk of surgical complications during dental implant placement. By using cone beam computed tomography (CBCT) imaging and a computer-guided implant treatment software program before any invasive procedure, it is possible to assess ridge morphology and understand the surgical complexity and risk level.

PURPOSE

The purpose of this radiological clinical study was to evaluate a large series of CBCT images to evaluate ridge shape variations along posterior mandibular edentulous regions and to clarify their associations with the level of implant planning complexity.

MATERIAL AND METHODS

One hundred and twenty CBCT files were analyzed retrospectively for a total 240 hemimandibular sites. Images of each edentulous region of the mandibular first and second premolar and first and second molar sites were evaluated in the sagittal plane. Ridge morphology and implant planning complexity per site were assessed. Categorical variables were presented as number of events and percentages. The chi-square test was used to compare the categorical variables (P=.05).

RESULTS

Of 491 partially edentulous mandibular sites, 235 were on the right, and 256 were on the left. Forty-two sites had a distal adjacent tooth, while 266 sites had no distal adjacent tooth. The sagittal bone sections demonstrated oblique (40.53%), straight (31.77%), S-shape (24.24%), hourglass (2.44%), and basal bone (1.02%) ridge morphologies. Implant complexity was deemed straightforward in 66.19% of sites, while 31.6% were identified as advanced and 2.54% as complex. When ridge morphology was evaluated from straight to basal-round bone shape, the implant complexity followed the same trend of change from a straightforward to complex procedure (P=.001) for edentulous second and first molar regions. No significant differences were noted at edentulous second premolar sites (P=.063). The missing second molar sites with oblique morphology were predicted to have 60.9% straightforward complexity, and first molar sites with oblique morphology had 55.8% straightforward implant complexity. Second premolars with straight ridge morphology had 71.7% straightforward complexity, whereas first premolars with the same shape had 92.5% straightforward implant complexity.

CONCLUSIONS

Careful evaluation of sagittal CBCT images can provide significant clinical information regarding ridge shape and anticipated surgical complexity before and at the time of implant placement. Surgical complexity is greatest at the most posterior mandibular edentulous sites, and extra attention and caution should be exercised during the surgical planning phases of implant surgery.

The success of using 2% lidocaine in pain removal during extraction of mandibular premolars: a prospective clinical study

BACKGROUND

The purpose of this study was to evaluate the anesthetic effectiveness of a buccal infiltration technique combined with local massage (using 2% lidocaine) in the extraction of mandibular premolars to be utilized as an alternative to the conventional inferior alveolar nerve block.

METHODS

Patients eligible included any subject with a clinical indication for tooth extraction of the mandibular 1st or 2nd premolars. All patients were anesthetized buccally by local infiltration technique followed by an external pressure applied for 1 min directly over the injection area. In each case, another local injection was given lingually. All operations were started at approximately 5 min after the buccal injection. The collected data included age, gender, pain perception and its intensity during treatment at three checkpoints, apical tenderness, and the type of extraction. Any associated complications or difficulties were also recorded. Then the results were analyzed and interpreted using appropriate statistical tests. The significance level was set at P ≤ 0.05.

RESULTS

A total of 247 cases (1st premolar, n = 119; 2nd premolar, n = 128), predominantly male, were included. In 95% of study sample, the patients were satisfied with the dental extraction without any pain. However, in 5% of cases, pain was reported at the stage of tooth removal. Apical tenderness was found to be present in 11% of the total cases. Three teeth required surgical removal. Upon analysis, no significant differences in the success rates were detected between the 2 premolar groups or amongst the various age groups. Minor and transient side effects were reported in this study.

CONCLUSION

The technique is simple and effective as well. It might be considered as an alternative anesthetic injection to the inferior alveolar nerve block for dental extraction of the mandibular premolars.