Evaluation of the mandible as an alternative autogenous bone source for oral and maxillofacial reconstruction

Virtual Three-Dimensional Model Analysis in the Assessment of the Maxillary and Mandibular Donor Sites on Cone-Beam Computed Tomography Images

Using the Mimics software to assess the maxillary and mandibular donor sites on cone-beam computed tomography (CBCT) images. This cross-sectional study was conducted on 80 CBCT scans. Data in DICOM format were transferred to the Mimics software version 21, and a maxillary and a mandibular mask according to cortical and cancellous bones were virtually created for each patient based on Hounsfield units (HUs). Three-dimensional models were reconstructed, and boundaries of donor sites, including mandibular symphysis, ramus, coronoid process, zygomatic buttress, and maxillary tuberosity, were defined. Virtual osteotomy was conducted on the 3D models to harvest bone. The volume, thickness, width, and length of harvestable bone from each site were quantified by the software. Data were analyzed by independent t-test, one-way ANOVA, and Tukey's test (alpha = 0.05). The greatest harvestable bone volume and length differences were observed between ramus and tuberosity (P < 0.001). The maximum and minimum harvestable bone volumes were found in symphysis (1753.54 mm3) and tuberosity (84.99 mm3). The greatest difference in width and thickness was noted between the coronoid process and tuberosity (P < 0.001) and symphysis and buttress (P < 0.001), respectively. Harvestable bone volume from tuberosity, length, width, volume from symphysis, and volume and thickness from the coronoid process was significantly greater in males (P < 0.05). The harvestable bone volume was the highest in symphysis, followed by ramus, coronoid, buttress, and tuberosity. The harvestable bone length and width were the highest in the symphysis and coronoid process, respectively. Maximum harvestable bone thickness was found in symphysis.

Volumetric Evaluation of Safe Zone for Bone Harvesting From Symphysis Region by Using Cone Beam Computed Tomography

OBJECTIVES

The aim of the present study was to retrospectively make a volumetric evaluation of symphysis sites of patients by the use of cone beam computed tomography (CBCT).

METHODS

This retrospective study evaluated dentate symphysis region of the mandibles in CBCT scans taken for different reasons in 90 patients (45 women and 45 men). Three-dimensional (3D) data were obtained using a CBCT device Kodak 9000 3D CMOS sensor with optical fiber. CBCT images were then transferred as digital imaging and communications in medicine files and imported into a volumetric-rendering software 3D DOCTOR (Able Software Corp., Lexington, MA) capable of measurements of vector based-segmentation technology for volumetric measurements.

RESULTS

The total average bone volume is 2616.45 mm. Significant differences in average bone volume were found between group I and group IV (P < 0.001). Higher bone volume was obtained in the male groups (2903.01 mm) than in the female groups (2329.88 mm).

CONCLUSIONS

CBCT is a good candidate for 3D assessment of high-contrast structures in the oral region. We suggest that the use of 3D computed tomography in combination with a software program is a dependable means of measuring the volume of the symphysis bone graft.

Quantitation of Mandibular Symphysis Bone as Source of Bone Grafting: Description in Class I and Class III Skeletal Conditions

The aim of this study was to quantify the cortical and cancellous bone in the mandibular symphysis and relate it to the teeth and to the skeletal class. A descriptive study was conducted using cone beam computerized tomography (CBCT). Class I and class III subjects were included, defined according to dental occlusion and cephalogram results. Linear measurements were taken on the CBCT of the mandibular canines, lateral incisors, and central incisors, where the analysis was related to the axial and apical axes considering the bone in relation to the dental area. With previous definitions, an observer took 2 measurements of the height of the mandibular symphysis, cortical bone of the buccal and lower region, and thickness of cancellous bone at different levels; the correlation coefficient between the first and second measurement was 0.99 and presented P = .001. The results were analyzed with analysis of variance and Tukey's honest significant difference test, with P < .05 being statistically significant. The symphysis height was significantly greater in class III subjects. The cortical bone was an average 1.67 ± 0.44 mm in vertical distance in the skeletal class I group and 1.74 ± 0.47 mm in the class III group. The cancellous bone had an average width of 5.03 ± 1.94 mm in the skeletal class I group and 4.74 ± 2.05 mm in the class III group. It was observed that cancellous bone was significantly thicker at the incisor level than at the canine level. There were anatomical differences between skeletal class I and class III subjects, although the clinical significance may be questionable. With the values from these analyses, it may be concluded that there are no significant differences in quantitation of the cortical and cancellous bone in the anterior mandibular symphysis.

Radiographic evaluation of the symphysis menti as a donor site for an autologous bone graft in pre-implant surgery

Purpose

This study was performed to obtain a quantitative evaluation of the cortical and cancellous bone graft harvestable from the mental and canine regions, and to evaluate the cortical vestibular thickness.

Materials and Methods

This study collected cone-beam computed tomographic (CBCT) images of 100 Italian patients. The limits of the mental region were established: 5 mm in front of the medial margin of each mental foramen, 5 mm under the apex of each tooth present, and above the inferior mandibular cortex. Cortical and cancellous bone volumes were evaluated using SimPlant software (SimPlant 3-D Pro, Materialize, Leuven, Belgium) tools. In addition, the cortical vestibular thickness (minimal and maximal values) was evaluated in 3 cross-sections corresponding to the right canine tooth (3_R), the median section (M), and the left canine tooth (3_L).

Results

The cortical volume was 0.71±0.23 mL (0.27-1.96 mL) and the cancellous volume was 2.16±0.76 mL (0.86-6.28 mL). The minimal cortical vestibular thickness was 1.54±0.41 mm (0.61-3.25 mm), and the maximal cortical vestibular thickness was 3.14±0.75mm(1.01-5.83 mm).

Conclusion

The use of the imaging software allowed a patient-specific assessment of mental and canine region bone availability. The proposed evaluation method might help the surgeon in the selection of the donor site by the comparison between bone availability in the donor site and the reconstructive exigency of the recipient site.

Simulation of sinus floor augmentation with symphysis bone graft using three-dimensional computerized tomography

The objective of this study was to evaluate the maximum amount of harvestable bone graft in the mandibular symphysis and the augmentation volume needed for different sinus lift levels (from 10 to 18 mm), in addition to calculating which sinus lift level can be acquired using the individual's symphysis bone graft volume with three-dimensional computerized tomography (3D CT) and software. Data from 15 CT scans was obtained from 15 adult patients (10 males, five females). The CT data, in DICOM format, was read into Mimics software from Materialize (Leuven, Belgium), with a slice thickness of 0.5 mm. The mandibular symphysis bone graft volumes and different levels of sinus lift augmentation volumes were calculated on the 3D images using Mimics software. It was determined that the average symphysis bone volume (3491.08+/-772.12 mm(3)) could provide approximately 14 mm of sinus lift height (3167.84+/-1067.65). 3D CT techniques and software can be used to calculate the required graft volume for sinus floor augmentation and symphysis bone graft volume, and the mandibular symphysis region can provide adequate bone volume for sinus lift augmentation.

Evaluation of volumetry and density of mandibular symphysis bone grafts by three-dimensional computed tomography

PURPOSE

Bone grafting before implant placing can improve the treatment in traumatized or regular implant patients. The aim of this study was to evaluate the density and maximum amount of harvestable bone graft in the mandibular symphysis.

MATERIALS AND METHODS

Data from 15 CT-scans were obtained from 15 adult patients (10 male/five female) for the purposes of this study. The CT data, in DICOM format, were read into Mimics software from Materialize (Leuven, Belgium), with a slice thickness of 0.5 mm. The volume, density, and dimensions based on Hounsfield units (HU) were measured on the 3D symphyseal bone graft using Mimics software.

RESULTS

The average bone volume calculated from the mandibular symphysis was 3491.08 +/- 772.12 mm(3). The average sized corticocancellous block that was measured was 38.75 x 11.05 x 7.80 mm. The mean bone density was 958.95 +/- 98.11 HU.

CONCLUSION

The use of three-dimensional computed tomography (3D CT) in combination with a software program is a reliable means of determining the density of graft, evaluating maximal volume and dimensions of the graft that can be harvested from the mandibular symphysis region.

Autogenous mandibular symphysis graft for orbital floor reconstruction: a preliminary study

OBJECTIVE

The present study aimed to evaluate and analyze postoperative results of Autogenous Mandibular Symphysis graft material for orbital floor reconstruction.

MATERIAL AND METHODS

A retrospective study was conducted on 11 patients, having an isolated blow out fracture (n=4) or orbital floor defects associated with other fractures (n=7). These fractures were reconstructed with Mandibular symphysis bone grafts. The Grafts were used where the defects were more than 1.5 centimeter [1]in diameter. Follow up as long as 1.5 year was kept. Patients were evaluated at recall visits by checking various extraoccular movements. Evidence of any complications like diplopia or enopthalmos, or rejection of graft or any symptoms of infection, or of paresthesia was recorded.

RESULTS

During a 1.5 year period of follow up, most of the patients had no postoperative complaints. There was good restoration of the orbital floor, with no clinical evidence of enopthalmos or diplopia. Extraoccular movements were intact in all patients. Only one patient presented with the symptoms of infection at a follow up period of 9 months. The infection subsided after removal of titanium plates, used for the stabilization of graft.

CONCLUSION

Autogenous Mandibular Symphysis graft is a good alternative with minimal morbidity for orbital floor reconstruction. The contour as well as the size of the graft available from symphysis region best suits for orbital floor reconstruction.

Quantitation of mandibular symphysis volume as a source of bone grafting

BACKGROUND

Autogenous intramembranous bone graft present several advantages such as minimal resorption and high concentration of bone morphogenetic proteins. A method for measuring the amount of bone that can be harvested from the symphysis area has not been reported in real patients.

PURPOSE

The aim of the present study was to intrasurgically quantitate the volume of the symphysis bone graft that can be safely harvested in live patients and compare it with AutoCAD (version 16.0, Autodesk, Inc., San Rafael, CA, USA) tomographic calculations.

MATERIALS AND METHODS

AutoCAD software program quantitated symphysis bone graft in 40 patients using computerized tomographies. Direct intrasurgical measurements were recorded thereafter and compared with AutoCAD data. The bone volume was measured at the recipient sites of a subgroup of 10 patients, 6 months post sinus augmentation.

RESULTS

The volume of bone graft measured by AutoCAD averaged 1.4 mL (SD 0.6 mL, range: 0.5-2.7 mL). The volume of bone graft measured intrasurgically averaged 2.3 mL (SD 0.4 mL, range 1.7-2.8 mL). The statistical difference between the two measurement methods was significant. The bone volume measured at the recipient sites 6 months post sinus augmentation averaged 1.9 mL (SD 0.3 mL, range 1.3-2.6 mL) with a mean loss of 0.4 mL.

CONCLUSION

AutoCAD did not overestimate the volume of bone that can be safely harvested from the mandibular symphysis. The use of the design software program may improve surgical treatment planning prior to sinus augmentation.

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.