Diagnostic Potential of Panoramic Radiography and CBCT in Detecting Implant-Related Ex Vivo Injuries of the Inferior Alveolar Canal Border.

The aim of this ex vivo study was to compare the diagnostic performances of panoramic radiography and cone beam computerized tomography (CBCT) in detecting implant-related injuries of the inferior alveolar canal. Monocortical bone windows were created in 60 fresh sheep hemimandibles, the inferior alveolar canals were revealed and 120 dental implants were inserted. Three types of injuries, described as pilot drill damage (PDRILL), collapsing of the superior border of the canal (COLL), penetration of the implant tip into the canal (PENET) and one control group, were simulated. Standard (PANO) and dentition mode panoramic (PANO-DENT) images as well as CBCT data presented as multiplanar reconstruction (MPR) and cross-sectional (CROSS) views were evaluated by 6 observers who had also expressed their level of confidence to their final diagnosis. Intra- and interobserver agreement scores were rated good. The area under the curve (AUC) values and the confidence scores for CROSS and multiplanar reformation (MPR) views were both significantly higher than those of PANO and PANO-DENT (P < .05 for each) in PDRILL group. In COLL group, observers showed less confidence to PANO and PANO-DENT compared to CROSS and MPR techniques (P < .05 for each). No other significant differences were found. Within the limits of this experimental study, it can be suggested that the standard and dentition modes of panoramic radiography can be as effective as CBCT in the detection of penetrating and collapsing injuries, but multiplanar and cross-sectional views of the CBCT are more accurate than panoramic radiography in the detection of pilot drill injuries in sheep mandible.

The Influence of the Gonial Angle on the Initial Biomechanical Stability of the Plate Osteosynthesis in Polyurethane Mandibles With Angle Fractures.

The aim of the present study was to examine the biomechanical stability of the mandibular angle fractures (MAF) fixated with standard titanium miniplates in polyurethane models with different gonial angles (GA). Three custom molds were prepared for 3-dimensional printed mandibles with low, normal and high GA. Twenty polyurethane replicas were cast per group and standard MAFs were created on each sample. Fractures were stabilized with 1 4-hole standard titanium miniplate inserted over the superior alveolar border. Half of the samples were subjected to molar loading and the other half to the incisal loading up until 150 N force magnitude. The load-displacement curves and the horizontal moment arms were recorded and analyzed. The samples with high GA demonstrated greater displacement than those with normal and low GA during molar loading (P < 0.05 for both). After correcting for the effects of the moment arm, the incisal loading also resulted in higher mean displacement in the high GA group than the others (P < 0.05 for both) and the normal GA samples showed higher displacement after 100 N level compared to those in low GA (P < 0.05). Within the limits of this in vitro study, it can be concluded that the MAFs of the polyurethane mandibles with high GA fixated with 1 standard monocortical plate are more likely to demonstrate higher displacement values under the effects of the molar and incisal loadings than do the mandibles with normal and low GA.

Direct Three-Dimensional Diagnosis of Ex Vivo Facial Fractures.

The aim of the present study is to assess the reliability and accuracy of different 3-dimensional (3D) reconstruction algorithms in detecting undisplaced condylar, zygomatic arc, and orbital rim fractures based on cone-beam computed tomography data set. Twenty sheep heads were used in the present study. Sixty fractured and 60 nonfractured (control) zones were randomly allocated. Three groups consisting of nondisplaced fractures of condyle (CF, n = 20), orbital (OF, n = 20), and zygomatic arc (ZF, n = 20) were created by using a diamond cutting disc. Soft tissues were only dissected and no fractures were generated in the control group (n = 60). The 3D reconstructions were created by using multiplanar reconstruction (MPR), surface rendering (SR), volume rendering (VR), and maximum intensity projection (MIP) algorithms. Final 3D models were examined in Osirix software (Pixmeo SARL, Bernex, Switzerland) by 6 observers. Diagnostic accuracies of each algorithm were statistically compared by receiver operating characteristics (ROC) and area under the ROC curves (AUCs). For the detection of CF, AUC for VR algorithm was found to be statistically larger than that of MIP while AUCs for VR and MIP were larger than those of MPR and SR for OF detection. For the detection of ZF, AUCs for MPR and VR were significantly larger than those of MIP and SR (P < 0.05 for each). Within the limitations of this experimental study, it can be concluded that for maxillofacial surgeons, it is more likely to detect condylar, orbital, and zygomatic fractures by using VR algorithm in 3D reconstruction.

The effect of the mandibular plane angle on fracture line stability: An ex vivo experimental study.

BACKGROUND/AIMS: Mandibular angle fractures fixated with plate osteosynthesis techniques have to withstand the effects of muscle attachments. Individual variations in the craniofacial morphology may alter the biomechanical resistance of the bone-plate construct. The aim of the present study was to determine the influence of variations in the mandibular plane angle (MPa) on the biomechanical stability of sheep mandibular angle fractures (MAFs). MATERIALS AND METHODS: Sixty sheep hemi-mandibles were used. The mandibles were positioned on a test jig that simulated low (15°, group L), normal (25°, group N), and high (35°, group H) MPa. Unfavorable MAFs were created with thin diamond cutting disks. One four-hole, 9.0-mm-spacing, standard titanium miniplate of 2.0 mm thickness and 5.0-mm-long screws were inserted at the superior border of the alveolar bone in monoplanar orientation. Specimens were then subjected to vertical loads between 10 N and 150 N in a universal testing machine. The displacement values at each 10 N force increment and the load magnitude at which 3.0 mm displacement limit was reached were recorded. RESULTS: Starting from 40 N, the displacement values at each 10 N increment in the H group were significantly higher than those of the L and N groups until 150 N (P < 0.05). The force magnitude required to reach 3.0 mm of displacement in the H group was significantly lower than that for the L and N groups (P < 0.05 for each). CONCLUSIONS: The one-miniplate monoplanar fixation technique used in sheep MAF with high MPa is more likely to offer lower biomechanical resistance to the vertical forces applied over the molar region than do the normal and low MPa.

A comparison of panoramic radiography and cone beam computed tomography in the detection of osteosynthesis complications in sheep mandibular angle fractures.

OBJECTIVE: The aim of this study was to compare the diagnostic efficacy of panoramic radiography (PANO) and cone beam computed tomography (CBCT) in detecting simulated complications of plate osteosynthesis applied to mandibular angle fractures (MAFs). STUDY DESIGN: Unfavorable MAFs were created in 100 fresh sheep hemimandibles. Fractures were fixed with 4-hole titanium miniplates and screws. Bone necrosis around the screws, penetration of the screw into the inferior alveolar canal, screw loosening, and plate breakage were simulated. The diagnostic efficacy of the imaging techniques was compared by using intra- and interobserver agreement scores and area under the receiver operating characteristic curve (AUC) values. Examination time (ET), confidence scores (CS), and planar preference (PP) in CBCT evaluation were assessed. RESULTS: Intra- and interobserver agreement scores varied between 0.61 and 0.91. AUCs for screw penetration into the inferior alveolar canal and screw loosening were significantly higher in CBCT than in PANO (P < .05). CBCT presented significantly higher ET and CS values compared with PANO (P < .05). PP showed significant differences among types of complications (P < .05). CONCLUSIONS: PANO provided acceptable outcomes in the detection of bone necrosis and broken plates around the screw, but CBCT was more likely to enable detection of all simulated types of complications with higher confidence.

Displacement of a Broken Dental Injection Needle Into the Perivertebral Space.

Dental injection needle breakage is an uncommon problem in dental practice. Displacement of the broken fragment into anatomical spaces is, on the other hand, a serious complication that occurs most commonly during inferior alveolar nerve blocks as a result of material wear, incorrect application of the anesthesia technique, or sudden movement of the patient during injection. Further complications such as infection, trismus, and nerve paralysis may exacerbate the condition and, if not treated adequately, life-threatening conditions may develop over time as the fragment dislodges deeper in soft tissues. Clinical symptoms of the patient, as well as the findings gathered from detailed physical examination and radiographic evaluation, are important factors to consider before performing an exploratory surgery. Removal of a broken needle may be troublesome due to its proximity to vital anatomic structures. Multislice computed tomography is a reliable imaging modality that provides accurate information to pinpoint the exact location of the needle fragment.This report describes a case of needle breakage occurred during inferior alveolar nerve block which was performed to extract a third molar tooth and the migration of the broken fragment from the right mandibular ramus area into the perivertebral space, with special emphasis on the surgical retrieval technique with multiplanar computed tomography imaging guidance.

The effects of low-level laser therapy on the healing of bone defects in streptozotocin-induced diabetic rats: A histological and morphometric evaluation.

BACKGROUND: The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) on the healing of bone defects in rats with streptozotocin (STZ)-induced DM. METHODS: 28 male Sprague-Dawley rats were used in this study. 14 animals received a single dose of STZ intraperitoneally (65 mg/kg) to induce Type I DM, whereas others were injected only with sterile saline solution. Four weeks later, standard bone defects were created in the tibiae of rats. Surgical wounds in one group from each of the diabetic and non-diabetic animals were irradiated with diode laser for every other day for 4 weeks and they were described as DM + LLLT and CONT + LLLT groups, respectively. Remaining two groups received no laser treatment. New bone formation, osteoblast and blood vessel counts were calculated in histologic sections. RESULTS: DM group had significantly smaller bone area and lower blood vessel count when compared to DM + LLLT, CONT and CONT + LLLT groups (p < 0.05 for each). CONT and CONT + LLLT groups had significantly larger bone area than DM + LLLT group (p < 0.05 for both). CONCLUSIONS: LLLT application promoted vascularization and new bone formation in animals with DM to a limited extent, since it was unable to support the healing process up to the level of non-diabetic animals.

The effects of supplemental melatonin administration on the healing of bone defects in streptozotocin-induced diabetic rats.

OBJECTIVE: The aim of this study was to investigate histologic and biochemical effects of supplemental melatonin administration on bone healing and antioxidant defense mechanism in diabetic rats. MATERIAL AND METHODS: Eighty-six Sprague-Dawley male rats were used in this study. Diabetes mellitus was induced by intraperitoneal (i.p.) administration of 65 mg/kg streptozotocin (STZ). Surgical bone defects were prepared in the tibia of each animal. Diabetic animals and those in control groups were treated either with daily melatonin (250 µg/animal/day/i.p.) diluted in ethanol, only ethanol, or sterile saline solution. Rats were humanely killed at the 10th and 30th postoperative days. Plasma levels of Advanced Oxidation Protein Products (AOPP), Malondialdehyde (MDA), and Superoxide Dismutase (SOD) were measured. The number of osteoblasts, blood vessels and the area of new mineralized tissue formation were calculated in histologic sections. RESULTS: At the 10th day, DM+MEL (rats receiving both STZ and melatonin) group had significantly higher number of osteoblasts and blood vessels as well as larger new mineralized tissue surfaces (p<0.05 for each) when compared with DM group. At the 30th day, DM group treated with melatonin had significantly lower levels of AOPP and MDA than those of DM group (p<0.05). CONCLUSION: Melatonin administration in STZ induced diabetic rats reduced oxidative stress related biomarkers and showed beneficial effects on bone healing at short term.

The effects of supplemental melatonin administration on the healing of bone defects in streptozotocin-induced diabetic rats

ABSTRACT Diabetes mellitus (DM) causes an increased production of free radicals that can impair bone healing. Melatonin is a hormone secreted mainly by the pineal gland, which participates in the neutralization process of free radicals. Objective The aim of this study was to investigate histologic and biochemical effects of supplemental melatonin administration on bone healing and antioxidant defense mechanism in diabetic rats. Material and Methods Eighty-six Sprague-Dawley male rats were used in this study. Diabetes mellitus was induced by intraperitoneal (i.p.) administration of 65 mg/kg streptozotocin (STZ). Surgical bone defects were prepared in the tibia of each animal. Diabetic animals and those in control groups were treated either with daily melatonin (250 μg/animal/day/i.p.) diluted in ethanol, only ethanol, or sterile saline solution. Rats were humanely killed at the 10th and 30th postoperative days. Plasma levels of Advanced Oxidation Protein Products (AOPP), Malondialdehyde (MDA), and Superoxide Dismutase (SOD) were measured. The number of osteoblasts, blood vessels and the area of new mineralized tissue formation were calculated in histologic sections. Results At the 10th day, DM+MEL (rats receiving both STZ and melatonin) group had significantly higher number of osteoblasts and blood vessels as well as larger new mineralized tissue surfaces (p<0.05 for each) when compared with DM group. At the 30th day, DM group treated with melatonin had significantly lower levels of AOPP and MDA than those of DM group (p<0.05). Conclusion Melatonin administration in STZ induced diabetic rats reduced oxidative stress related biomarkers and showed beneficial effects on bone healing at short term.