Relevant factors of posterior mandible lingual plate perforation during immediate implant placement: a virtual implant placement study using CBCT

Evaluation of submandibular fossa depth and mandibular canal relationship with cone-beam computed tomography

BACKGROUND

Before performing surgical procedures in the posterior mandible, which contains vital structures, it is essential to have detailed knowledge of the morphology, depth, types, and variations of the submandibular fossa (SMF), as well as the precise course of the mandibular canal (MC) to avoid a possible perforation. The aim of this study was to evaluate the relationship between the depth and types of SMF, and the MC position using cone beam computed tomography (CBCT) images in a sample of Turkish individuals.

METHODS

The depth and type of SMF, and relative position of the MC to the deepest point of the SMF (classified as inferior, parallel, or superior), were retrospectively evaluated on cross-sectional CBCT images. The Wilcoxon Signed Rank Test, Mann-Whitney U test, Spearman correlation coefficient, Kruskal-Wallis H test, and Chi-square test were used to analysis of the variables. A p value of less than 0.05 was accepted as significant.

RESULTS

The submandibular fossa depth (SMFD) was measured on the left and right sides of CBCT images of 610 patients (358 female, 252 male). A significant difference was observed between the left and right sides for mean SMFD (1.93 ± 0.65 and 1.98 ± 0.67, respectively) (p = 0.001). The mean SMFD values were found to be significantly higher in males than in females on both sides (p < 0.001). The position of the MC in relation to the deepest point of the SMF was most frequently observed to be inferior. The lowest mean SMFD value was observed in the parallel position on the left and right sides (1.79 ± 0.56 and 1.77 ± 0.53, respectively).

CONCLUSIONS

The anatomical data obtained from this study contribute to the existing literature on SMFD and its relationship with the MC. It is recommended that these anatomical structures be evaluated radiologically before surgical procedures to prevent complications.

Factors influencing submandibular fossa visibility on panoramic images: a comparative CBCT study

OBJECTIVE

This study aimed to investigate the variables affecting the visibility of the submandibular fossa (SF) on panoramic images, including SF depth and types, age, gender, presence or absence of tooth, location of mandibular canal, and alveolar bone thicknesses.

METHODS

Cone beam computed tomography (CBCT) images and conventional panoramic images of 150 patients were analyzed retrospectively. The visibility of the SF on panoramic images was compared with its depth and adjacent alveolar bone thicknesses on CBCT. Predictive variables affecting the SF visibility were identified, and binary logistic regression analysis was performed.

RESULTS

Based on CBCT measurements, the SF depth was ≥ 2 mm in 65% of the hemi-mandibles with radiolucent area (26.7%). A significant difference was observed between the SF visibility on panoramic images and its depth, and the lingual cortical bone thickness as measured on CBCT. When the SF was visible and not, the mean SF depth was 2.24 ± 0.97 mm and 1.6 ± 0.8 mm, and lingual cortical bone thickness was 1.27 ± 0.47 mm and 1.53 ± 0.49, respectively. Regression analysis revealed significant associations between SF visibility and gender (Odds ratio (OR) = 3.28, 95% confidence interval (CI): 1.77-6.09), age (OR = 0.96, 95% CI: 0.94-0.98), SF depth (OR = 2.01, 95% CI: 1.43-2.81), and lingual cortical bone thickness (OR = 2.02, 95% CI: 1.30-3.16).

CONCLUSIONS

A prominent radiolucent SF on panoramic images indicates a deeper fossa and thinner lingual cortical bone, necessitating caution by clinicians during surgical planning.

Incidental Findings Following Dental Implant Procedures in the Mandible: A New Post-Processing CBCT Software Analysis

Background/Objectives: The aim of this study was to evaluate incidental findings in the mandible after the placement of dental implants using a new cone-beam computed tomography (CBCT) software. Methods: The initial sample consisted of 2872 CBCT scans of patients of both sexes. The parameters evaluated in this study were the location of the implants in the mandible, implant length, anatomical relationship of the implant with the mandibular canal, presence or absence of damage to the adjacent teeth, presence or absence of implant fractures, and presence or absence of bone support. Fisher's exact test was performed to compare the variables. The significance level was set at p = 0.05. Results: Out of 2872 CBCT scans, 214 images of patients with an average age of 44.5 years were included. The most frequent location of the implants was the posterior region (93.5%), with 54% of the implants having a length between 9 and 14 mm. It was found that 92% of the implants were positioned above the mandibular canal. Damage to adjacent teeth was observed, with no correlation with the implant positioning (p = 1.000). In 100% of cases of implants in the anterior region, there was bone support. Fracture was observed in 1.7% of implants with a length between 9 and 14 mm. Conclusions: The installation of implants in the mandible occurs more frequently in the posterior region, with a high presence of bone support and a low incidence of damage to adjacent teeth, anatomical structures, and fractures.

Accuracy in osteotomy drilling using a new universal and disposable drill-stop device for dental implant drills: an in vitro study using a bovine rib model

BACKGROUND

This study aimed to evaluate the surgical accuracy of a new universal disposable stop system for implant drills (FCA Universal Drill Stop).

MATERIAL AND METHODS

A total of 60 bovine ribs were included in this in vitro study. The ribs were randomized into three study groups (n=20 ribs per group). In each study group (Group1: drills without stop or control group, Group 2: prefabricated drills with stop or gold standard group, and Group 3: drills with FCA Universal Drill Stop) a total of 100 osteotomies were performed with implant drills in each group, following the drilling sequence for the placement of a dental implant of 10 mm length and 4 mm diameter. The accuracy of the depth of the osteotomies was quantified clinically (with periodontal probe) and radiologically, using ImageJ version 1.48v software.

RESULTS

The order of highest to lowest accuracy (clinical and radiological) in the depth of osteotomies was: FCA Universal Drill Stop> prefabricated drills with a stop>drills without stop, with statistically significant differences being observed between both systems with stop with respect to the control group, although not between them.

CONCLUSIONS

The new universal disposable stop system for implant drills, offers similar accuracy to prefabricated drills with stop, with both systems being much more accurate than implant drills without stop. Although this experimental evaluation showed favourable results, further clinical studies are necessary.

The mylohyoid line is highly variable but does not affect the microarchitecture of the edentulous alveolar bone - an anatomical micro-CT study

OBJECTIVES

To evaluate in the absence of teeth the variability of the mylohyoid line (ML), the microarchitecture of the adjacent bone, and whether the variable prominence/width of the ML is associated with the quality of the adjacent bone.

METHODS

µCT scans of 28 human mandibles from anatomical specimens were analyzed. The following parameters were assessed in four edentulous areas (first and second premolar (PM), first, second, and third molar (M1/2/3)): ML width, cortical thickness (CtTh), average cortical- (Avg.Ct.BV/TV), and trabecular bone volume fraction (Avg.Tb.BV/TV).

RESULTS

The ML width increased from the PM towards the M2 region, which also showed the highest variance (range: 0.4-10.2 mm). The CtTh showed a decrease in the M3 region, while Avg.Ct.BV/TV and Avg.Tb.BV/TV hardly differed among the regions. In the multivariable model on the effect of the various parameters on the ML width, only gender and tooth region were significant. Specifically, male specimens were associated with a wider ML width compared to female specimens and the M2 region was associated with a wider ML width compared to the other tooth regions.

CONCLUSION

The ML width was not associated with the cortical and trabecular bone quality in the adjacent bone, while gender and tooth region had a significant effect. Specifically, the ML width was lower in female, but peaked in the M2 region with a median width of 3-4 mm.

CLINICAL RELEVANCE

From a clinical point of view, it was confirmed that the ML is in general a highly variable structure, especially in the M2 region, but the ML width does not allow any conclusions on the bone quality. Altogether, this underlines the need for an individual and accurate diagnostic prior to any surgical intervention.

Quantitative and qualitative 3D analysis of mandibular lingual concavities: Implications for dental implant planning in the posterior mandible

OBJECTIVE

The purpose of this study is to investigate the type of ridge (degree of angulation of the lingual concavity) and the buccolingual dimensions in the area of the first and second molars in both genders of different ages and how this will affect implant placement in the posterior mandible.

MATERIALS AND METHODS

This retrospective cross-sectional study comprised cone beam computed tomography images of 150 dental patients (75 males and 71 aged ≥30). The following were measured/reported: type (morphology) of the ridge (convex [C], parallel [P], or undercut [U]), buccolingual width at the base and the crest of the ridge, and ridge height. The concavity angle, depth, and length of the U-shaped ridge were measured too.

RESULTS

The prevalence of type U ridge ranged from 32.7% in the first molar region to 62.7% in the second molar region. Almost all measurements and ridge type distributions were comparable amongst the age groups (p > .05). Very few significant differences were found when comparing #36 versus #37 and #46 versus #47 teeth, with no differences in the distribution of the ridge types (p > .05). Quite the inverse, all measurements were statistically different when comparing #36 versus #37 and #46 versus #47 teeth, and type U ridge was more frequent in second molar compared to the first molar regions, respectively (p < .05). Many measurements were statistically higher in females; the inverse was true for a few measurements (p < .05). Type U ridge in #36 and #37 was found more frequently among males (p < .001). In contrast, the ridge types in #37 and #47 were not statistically different gender-wise.

CONCLUSIONS

The U type of ridge was more prevalent in the investigated population, encountered more frequently in the second molars generally and in the first molars of males than females. Most posterior mandibular measurements are similar age- and side-wise but seem different gender- and tooth-wise.