Evaluation of maxillary trabecular microstructure as an indicator of implant stability by using 2 cone beam computed tomography systems and micro-computed tomography.

OBJECTIVE: The aim of this study was to assess the trabecular microarchitecture of the maxilla by using cone beam computed tomography (CBCT) and micro-computed tomography (micro-CT) ex vivo. STUDY DESIGN: Seventeen maxillary cadaver specimens were scanned by using micro-CT and CBCT devices. Samples were scanned with 2 CBCT devices at different voxel sizes (0.08, 0.125, and 0.160 mm for 3-D Accuitomo 170; 0.75 and 0.200 mm for Planmeca Promax 3-D Max). Morphometric parameters, such as bone volume/total volume (BV/TV) ratio, trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), and degree of anisotropy (DA) were assessed by using CTAnalyzer software. Bland-Altman limits of agreement and intraclass correlation coefficient (ICC) were performed to evaluate agreement between CBCT and micro-CT in consideration of measured morphometric parameters. Statistical significance was set at P < .05. RESULTS: The BV/TV, Tb.Th, Tb.Sp, and DA values were higher for CBCT images compared with micro-CT images, whereas the Tb.N value was lower with CBCT images than with micro-CT images. The BV/TV and DA parameters showed the highest agreement between CBCT and micro-CT devices (ICC = 0.421 for BV/TV and ICC = 0.439 for DA; P < .01). CONCLUSIONS: The BV/TV and DA parameters measured on CBCT obtained at the smallest voxel size were found to be useful for the assessment of maxillary trabecular microstructure.

Accuracy of virtual models in the assessment of maxillary defects.

PURPOSE: This study aimed to assess the reliability of measurements performed on three-dimensional (3D) virtual models of maxillary defects obtained using cone-beam computed tomography (CBCT) and 3D optical scanning. MATERIALS AND METHODS: Mechanical cavities simulating maxillary defects were prepared on the hard palate of nine cadavers. Images were obtained using a CBCT unit at three different fields-of-views (FOVs) and voxel sizes: 1) 60×60 mm FOV, 0.125 mm(3) (FOV60); 2) 80×80 mm FOV, 0.160 mm(3) (FOV80); and 3) 100×100 mm FOV, 0.250 mm(3) (FOV100). Superimposition of the images was performed using software called VRMesh Design. Automated volume measurements were conducted, and differences between surfaces were demonstrated. Silicon impressions obtained from the defects were also scanned with a 3D optical scanner. Virtual models obtained using VRMesh Design were compared with impressions obtained by scanning silicon models. Gold standard volumes of the impression models were then compared with CBCT and 3D scanner measurements. Further, the general linear model was used, and the significance was set to p=0.05. RESULTS: A comparison of the results obtained by the observers and methods revealed the p values to be smaller than 0.05, suggesting that the measurement variations were caused by both methods and observers along with the different cadaver specimens used. Further, the 3D scanner measurements were closer to the gold standard measurements when compared to the CBCT measurements. CONCLUSION: In the assessment of artificially created maxillary defects, the 3D scanner measurements were more accurate than the CBCT measurements.

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars.

PURPOSE: This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. MATERIALS AND METHODS: Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. RESULTS: The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. CONCLUSION: Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

Effect of implant design and bioactive glass coating on biomechanical properties of fiber-reinforced composite implants.

This study aimed to evaluate the influence of implant design and bioactive glass (BAG) coating on the response of bone to fiber-reinforced composite (FRC) implants. Three different FRC implant types were manufactured for the study: non-threaded implants with a BAG coating; threaded implants with a BAG coating; and threaded implants with a grit-blasted surface. Thirty-six implants (six implants for each group per time point) were installed in the tibiae of six pigs. After an implantation period of 4 and 12 wk, the implants were retrieved and prepared for micro-computed tomography (micro-CT), push-out testing, and scanning electron microscopy analysis. Micro-CT demonstrated that the screw-threads and implant structure remained undamaged during the installation. The threaded FRC/BAG implants had the highest bone volume after 12 wk of implantation. The push-out strengths of the threaded FRC/BAG implants after 4 and 12 wk (463°N and 676°N, respectively) were significantly higher than those of the threaded FRC implants (416°N and 549°N, respectively) and the nonthreaded FRC/BAG implants (219°N and 430°N, respectively). Statistically significant correlation was found between bone volume and push-out strength values. This study showed that osseointegrated FRC implants can withstand the static loading up to failure without fracture, and that the addition of BAG significantly improves the push-out strength of FRC implants.

Nerve damage assessment following implant placement in human cadaver jaws: an ex vivo comparative study.

The present study compared the use of cone beam computerized tomography (CBCT) images and intra-oral radiographs in the placement of final implant drills in terms of nerve damage to cadaver mandibles. Twelve cadaver hemimandibles obtained from 6 cadavers were used. Right hemimandibles were imaged using peri-apical radiography and left hemimandibles using CBCT, and the images obtained were used in treatment planning for the placement of implant drills (22 for each modality, for a total of 44 final drills). Specimens were dissected, and the distances between the apex of the final implant drill and the inferior alveolar neurovascular bundle and incisive nerve were measured using a digital calliper. Nerves were assessed as damaged or not damaged, and the Chi-square test was used to compare nerve damage between modalities (P < 0.05). Nerve damage occurred with 7 final drills placed based on peri-apical radiography (31.8%) and 1 final drill placed using CBCT images (4.5%). The difference in nerve damage between imaging modalities was statistically significant (P = 0.023), with CBCT outperforming intraoral film in the placement of final implant drills ex vivo. In order to prevent nerve damage, CBCT is recommended as the principal imaging modality for pre-implant assessment.

Accuracy of a newly developed cone-beam computerized tomography-aided surgical guidance system for dental implant placement: an ex vivo study.

The aim of the present study was to measure the accuracy of the cone-beam computerized tomography (CBCT)- aided StentCad Beyond surgical guidance system and to compare bone-supported and tooth/bone-supported guidance by using this system in dental implant placement ex vivo. Five cadaver mandibles were scanned using an Iluma CBCT scanner. After scanning, DICOM slices were transferred to the StentCad Beyond implant simulation software, which was used for preoperative implant planning. Using the StentCad Beyond guidance system, 9 implant drills were inserted using a bone-supported guidance system and 11 using a tooth/bone-supported guidance system. Mandibles were scanned again and these data were transferred to the StentCad Beyond software. Pre- and postoperative information was superimposed using the Rhinoceros version 4 software program, and deviations between planned and actual drill positions were calculated for each implant. In addition, differences between bone-supported and tooth/bone-supported guidance systems were analyzed by t-test, with a significance level of P < .05. Data analysis found a mean coronal deviation of 1.2 ± 0.3 mm and 0.6 ± 0.6 mm, mean apical deviation of 1.3 ± 0.6 mm and 0.7 ± 0.6 mm, mean apical and coronal depth deviation of 1.4 ± 0.3 mm and 1.3 ± 0.3 mm, and mean angular deviation of 4.2° ± 2.0° and 3.0° ± 1.5° for tooth/bone supported and bone-supported guides, respectively. No statistical differences were found in depth or angular deviations between groups (P > .05); however, statistically significant differences between groups were found in mean horizontal coronal deviation (P = .016) and mean horizontal apical deviation (P = .047). The StentCad Beyond system was found to be a reliable guide for placing implants ex vivo.

Analgesic effect of Anatolian propolis in mice.

OBJECTIVES: The aim of the present study was to assess the analgesic effect of Anatolian propolis, which is added to toothpastes as a prophylactic component for periodontal diseases. METHODS: Water-, ethanol- and acetone-extracted Anatolian propolis were prepared. The analgesic effect of the extracts was assessed using the tail-flick test in mice (n=6 per extract). Comparison among groups was made using one-way ANOVA, followed by post-hoc Scheffe test to determine significant differences among the means of the data groups. P<0.05 was accepted as indicating a significant difference. RESULTS: We found that water-extracted Anatolian propolis caused a significant increase, 1.61-fold (p<0.001 versus control), in the latency time using tail-flick test in mice. However, acetone-extracted and ethanol-extracted propolis led to no significant effect. CONCLUSION: We proved the analgesic effect of water-extracted Anatolian propolis. Thus, propolis used in the composition of toothpastes may be beneficial in terms of its analgesic action in addition to its other favorable effects.

Accuracy of CBCT measurements of a human skull.

The purpose of this study is to assess the accuracy and reproducibility of cone-beam computed tomography (CBCT) measurements of a human dry skull by comparing them to direct digital caliper measurements. Heated gutta-percha was used to mark 13 specific distances on a human skull, and the distances were directly measured using a digital caliper and on CBCT images obtained with Iluma (3M Imtec, OK, USA) and 3D Accuitomo 170 (3D Accuitomo; J Morita Mfg. Corp., Kyoto, Japan) CBCT imaging systems. Iluma images were obtained at 120 kVp and 3.8 mA and reconstructed using voxel sizes of 0.2 and 0.3 mm(3). Accuitomo images were obtained at 60 kVp and 2 mA and a voxel size of 0.250 mm(3). In addition, 3-D reconstructions were produced from images obtained from both systems. All measurements were made independently by three trained observers and were repeated after an interval of 1 week. Agreement between observers and image type was assessed by calculating Pearson correlation coefficients, with a level of significance set at p < 0.05. Pearson correlation coefficients between readings ranged from 0.995 to 1 for all image types. Correlations among observers were also very high, ranging from 0.992 to 1 for the first reading and from 0.992 to 1 for the second reading for the different image types. All CBCT image measurements were identical and highly correlated with digital caliper measurements. Accuracy of measurements of various distances on a human skull obtained from different CBCT units and image types is comparable to that of digital caliper measurements.

An Assessment of the Relationship between the Maxillary Sinus Floor and the Maxillary Posterior Teeth Root Tips Using Dental Cone-beam Computerized Tomography.

OBJECTIVES: The aim of the present study was to assess the relationship between the maxillary sinus floor and the maxillary posterior teeth root tips using dental cone-beam CT. METHODS: A total of 87 right and 89 left maxillary sinus regions from 92 patients were examined using dental cone-beam CT. Images were analyzed by a specialist in oral and maxillofacial radiology. Perpendicular lines were drawn on the cross-sectional images between the deepest point of the maxillary sinus floor and the root tips of the maxillary first and second premolars and first, second and third molars, and the distances were measured using built-in measurement tools. Means, standard deviations and minimum and maximum values were calculated for all right and left premolars and molars. T-tests were used to compare measurements between left and right sides and between female and male patients. RESULTS: The distance between sinus floor and root tip was longest for the first premolar root tip and shortest for the second molar buccodistal root tip for both right and left sides. No statistically significant differences were found between the right and left side measurements or between female and male patients (P>.05). CONCLUSIONS: Knowledge of the anatomical relationship between the maxillary sinus floor and the maxillary posterior teeth root tips is important for the preoperative treatment planning of maxillary posterior teeth.

Is endodontic treatment necessary during coronectomy procedure?

PURPOSE: Close proximity of the inferior alveolar nerve (IAN) to the third molar roots can result in nerve injuries during extraction of third molars. Consequently, it is necessary to determine the relationship of the nerve and roots to avoid damage to the IAN. Computed tomography scans are widely used to determine the correct relationship between the IAN and lower third molars. PATIENTS AND METHODS: The study consisted of 10 patients with 16 lower third molars in close relationship with the IAN who were divided into a study group and a control group. The patients in the study group were treated via coronectomies performed with endodontic treatments. The patients in the control group underwent coronectomies without endodontic treatment. The patients were followed up for at least 1 year. RESULTS: We had to extract 7 of the roots because of the infection in 8 patients belonging to the study group, which were treated endodontically. Moreover, there were 3 cases of IAN damage because of the extraction in the study group. However, in the control group, no infection was determined and IAN damage was absent. CONCLUSION: Coronectomy appears to be a reliable technique to protect the IAN from damage. This procedure has a low incidence of complications. Endodontic treatment does not affect the success of this method according to our results.

Supernumerary teeth in a Turkish population.

INTRODUCTION: Our aim in this study was to investigate the frequency, distribution, sex differences, and characteristics of supernumerary teeth in a referred Turkish population. METHODS: A total of 2599 patients' panoramic radiographs (1360 girls, 1239 boys) were evaluated, including children in both the mixed and the permanent dentitions. Their mean age was 8.6 +/- 0.23 years. Number, location, classification, side, and impaction of supernumerary teeth were evaluated. Furthermore, the development of these teeth was evaluated. RESULTS: Eighty-four supernumerary teeth were found on 69 radiographs; 9 were deciduous and 75 were permanent teeth. Most supernumerary teeth were in the premaxillary region (67%). Mesiodens (n = 43) was the most frequent supernumerary tooth (51.2%). This was followed by the maxillary lateral incisor (15.5%), the mandibular premolar (14.3%), the maxillary canine (9.5%), the maxillary premolar (6%), the mandibular lateral incisor (2.4%), and the mandibular canine (1.2%). Sixty-two (73.8%) supernumerary teeth were impacted. The male-female ratio was 1.13:1, which was not statistically significant. CONCLUSIONS: The prevalence of supernumerary teeth in Turkish children was 2.7% in this study.

Anatomic evaluation of maxillary sinus septa: surgery and radiology.

The anatomical structure of the maxillary sinus is fundamental to maxillofacial surgery. The presence of septa, located at the inner surface of the maxillary sinus, increases the risk of sinus membrane perforation during sinus elevation for dental implant surgery. The aim of this study was to evaluate the anatomy of maxillary sinus septa.Data in this study was obtained from a total of 205 cases. One hundred and seventy-seven patients were partially edentulous (PE) whereas 28 patients had no teeth. Dental computerized tomography (dental CT) was used in the assessment of 410 sinus segments (205 left and 205 right segments). The prevalence of sinus segments with septa was found to be 145/410. Septa were detected in 91 of the 177 PE cases. There were a total of 26 septa in 18 of the 28 completely edentulous (CE) cases. A total of 165 septa were detected in these segments. The prevalence of septa was 46.4% (26/56) in the CE, and 39.2% (139/354) in the PE segments. Thirty septa were found in the anterior, 110 in the middle and 25 in the posterior region. All detected septa were located mediolateral direction. Their relative position: lateral, middle or medial were also noted. The height measurements of the septa varied amongst the different positions. In view of the fact that septa of various heights and courses can develop in all parts of the maxillary sinus, timely and adequate assessment of the inner aspect of the maxillary sinus is essential to avoid complications during sinus augmentation procedures.

Measurements of mandibular canal region obtained by cone-beam computed tomography: a cadaveric study.

OBJECTIVE: The objective of this study was to assess the accuracy and reproducibility of cone-beam CT measurements of specific distances around the mandibular canal by comparing them to direct digital caliper measurements. METHODS: Six formalin-fixed hemimandible specimens were examined using the ILUMA cone-beam CT system. Images were obtained at 120 kVp, 3.8 mA, and a voxel size of 0.2 mm, with an exposure time of 40 seconds. Specimens were cut into sections at 7 locations using a Lindemann burr, and a digital caliper was used to measure the following distances on both the anterior and posterior sides of each section: Mandibular Width (W); Mandibular Length (L); Upper Distance (UD); Lower Distance (LD); Buccal Distance (BD); and Lingual Distance (LID). The same distances were measured on the corresponding cross-sectional cone-beam CT images using the built-in measurement software. All caliper and cone-beam CT measurements were made by 2 independent trained observers and were repeated after an interval of 1 week. The Bland/Altman method was used to calculate intra- and inter-rater reliability. Intra-class correlation coefficients (ICCs) from 2-way random effects model were calculated. Agreements between cone-beam CT and direct digital caliper were calculated by ICC for 6 distances and 2 observers. RESULTS: Intraobserver and interobserver measurements for all distances showed high agreement. ICCs for intraobserver agreement ranged from 0.86 to 0.97 for cone-beam CT measurements and from 0.98 to 0.99 for digital caliper measurements. ICCs between observers ranged from 0.84 to 0.97 for the cone-beam CT measurements and from 0.78 to 0.97 for the digital caliper measurements. ICCs for cone-beam CT and direct digital caliper ranged from 0.61 to 0.93 for the first observer and from 0.40 to 0.95 for the second observer. CONCLUSION: Accuracy of cone-beam CT measurements of various distances surrounding the mandibular canal was comparable to that of digital caliper measurements.

Interpretation of chemically created periapical lesions using 2 different dental cone-beam computerized tomography units, an intraoral digital sensor, and conventional film.

OBJECTIVE: To assess the diagnostic potential of 2 different cone-beam computerized tomography (CT) units and compare this with intraoral digital and conventional film in the detection of chemically created periapical lesions. STUDY DESIGN: Periapical lesions were created chemically in 27 intact roots of 23 teeth (6 incisors, 4 canines, 6 premolars, and 7 molars). Cone-beam CT and digital and film images of the teeth were obtained before and after the lesions were created. Three observers separately used a 5-point scale to rate the images for the presence or absence of periapical pathology. Images were scored twice by each observer, with an interval of 4 weeks. Kappa values were calculated to assess intra- and interobserver agreement. Data were analyzed using repeated-measures analysis of variance for nested designs. R(2) values were used to assess the models for each observer for each method. Differences between observers and methods were tested for statistical significance with the paired t test. RESULTS: Kappa coefficients for intraobserver agreement ranged from 0.196 to 0.542 for the 2-dimensional (2D) images and from 0.533 to 0.699 for the cone-beam CT images, whereas kappa coefficients for interobserver agreement ranged from 0.223 to 0.302 for the 2D images and from 0.417 to 0.461 for the cone-beam CT images. The R(2) values for each observer showed that cone-beam CT images were superior to 2D intraoral images. There was no difference between the 2 cone-beam CT units tested (P > .05), and no difference was found between the 2 intraoral radiographic techniques tested (P > .05). CONCLUSION: The 2 cone-beam CT units tested performed similarly, and both performed better than intraoral digital and film radiography in detecting chemically created periapical lesions.

The effect of mineral trioxide aggregate on the contractility of the rat thoracic aorta.

Mineral trioxide aggregate (MTA) is being advocated for vital pulp therapy. In the case of direct pulp capping, hemorrhage control is an important step on success, but little is known about the effect of MTA on pulpal bleeding. In addition, there has been a lack of information on the effect of MTA on smooth muscle contraction, such as can occur in the blood vessels of dental pulp. The present study assessed the vascular effects of MTA, using the rat aortic ring preparations as a tissue model. MTA (100-500 mg) induced dose-dependent contraction in rat thoracic aorta. The contractile effect of MTA was blocked by calcium channel blocker nifedipine (1 muM). These data suggest that the vasoconstrictor property of MTA is related to calcium influx and it may allow proper control of hemorrhage which is critical for the success of any pulp-capping treatment.

Oligodontia in pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is an inherited disorder that has both autosomal recessive and autosomal dominant pathways and is characterized by severe malformation of elastic and collagen fibers. Clinically, 3 main groups of systemic findings involving skin, eye, and vessels emerge in the symptoms. In this report, we present the case of a patient with PXE who has agenesis of most of the permanent teeth. No previous reports in the English literature have mentioned oligodontia in PXE. Our treatment plan consisted of extraction of the upper left deciduous canine followed by fixed orthodontic treatment. Further prosthodontic rehabilitation was planned to restore the edentulous area.

Vertical distraction osteogenesis of fibula transplant for mandibular reconstruction: a case report.

Bone continuity defects in the mandible are caused by tumor surgery, trauma, infection, or osteoradionecrosis. Today, reconstruction of long-span mandibular defects with a free fibular flap is a routine procedure. However the bone height of the mandible after reconstruction is about half that of the dentulous mandible. Therefore, the deficiency in bone height makes implant placement impractical. In our case, because it was necessary to restore the mandibular height, a vertical distraction osteogenesis was performed on the grafted mandible of the patient who was referred to our clinic with a reconstructed mandible owing to a gunshot injury. As a result, the vertical discrepancy between the fibula and the native hemimandible of the patient was corrected. And the placement of dental implants was performed without any complications. In conclusion, we believe that the vertical distraction osteogenesis of free vascularized fibula flaps is a reliable technique that optimizes implant positioning for ideal prosthetic rehabilitation.

Efficacy of low level laser therapy on neurosensory recovery after injury to the inferior alveolar nerve.

BACKGROUND: The most severe complication after the removal of mandibular third molars is injury to the inferior alveolar nerve or the lingual nerve. These complications are rather uncommon (0.4% to 8.4%) and most of them are transient. However, some of them persist for longer than 6 months, which can leave various degrees of long-term permanent disability. While several methods such as pharmacologic therapy, microneurosurgery, autogenous and alloplastic grafting can be used for the treatment of long-standing sensory aberrations in the inferior alveolar nerve, there are few reports regarding low level laser treatment. This paper reports the effects of low level laser therapy in 4 patients with longstanding sensory nerve impairment following mandibular third molar surgery. METHODS: Four female patients had complaints of paresthesia and dysesthesia of the lip, chin and gingiva, and buccal regions. Each patient had undergone mandibular third molar surgery at least 1 year before. All patients were treated with low level laser therapy. Clinical neurosensory tests (the brush stroke directional discrimination test, 2-point discrimination test, and a subjective assessment of neurosensory function using a visual analog scale) were used before and after treatment, and the responses were plotted over time. RESULTS: When the neurosensory assessment scores after treatment with LLL therapy were compared with the baseline values prior to treatment, there was a significant acceleration in the time course, as well as in the magnitude, of neurosensory return. The VAS analysis revealed progressive improvement over time. CONCLUSION: Low level laser therapy seemed to be conducive to the reduction of long-standing sensory nerve impairment following third molar surgery. Further studies are worthwhile regarding the clinical application of this treatment modality.