Three-rooted premolar analyzed by high-resolution and cone beam CT

Is the assessment of the mandibular molar danger zone affected by field of view and voxel size in cone beam computed tomography examinations?

OBJECTIVE

To verify if assessment of the danger zone (DZ) in the mesial root of mandibular molars is affected by field of view (FOV) and voxel sizes in cone beam computed tomography (CBCT) scans.

STUDY DESIGN

Forty mandibular molars were scanned by micro-computed tomography, creating the reference standard. The teeth were then submitted for CBCT scans with FOVs of 10 × 5.5 cm and 5 × 5.5 cm and voxel sizes of 0.4, 0.2, 0.15, and 0.075 mm3. The smallest dentin thickness in the DZ from the mesiobuccal and mesiolingual canals was measured at 2, 4, and 6 mm apical to the root furcation. Descriptive statistics, paired t-tests, and intraclass correlation coefficients were used for statistical analysis with significance established at P < .05.

RESULTS

All CBCT measurements overestimated the DZ dentin thickness (P < .001) compared to the reference standard. The greatest overestimation occurred in the 5 × 5.5 cm FOV with 0.4 mm3 voxels (P = .007). Dentin thickness measured with the 5 × 5.5 cm FOV and 0.075 mm3 voxels was significantly smaller and produced the best ICC value with the reference standard (0.936).

CONCLUSIONS

CBCT overestimates the dentin thickness of the DZ regardless of FOV and voxel sizes. The 5 × 5.5 cm FOV showed the best performance with the 0.075 mm3 voxel size, but it performed poorly with 0.4 mm3 voxels.

Bronchial balloon dilatation combined with cryotherapy for tuberculous cicatricial central airway stenosis, with Adobe Photoshop for the degree measurement: A multicenter, retrospective study

Objective

To explore bronchial balloon dilation (BD) combined with cryotherapy and Photoshop (PS)-base image processing technology in the interventional treatment of tuberculous cicatricial central airway stenosis (CCAS).

Methods

This multicenter, retrospective study analyzed the clinical data of patients with CCAS from six hospitals in Henan, China between June 2019 and October 2022.

Results

A total of 307 patients were included, including 152 (62 males) treated with BD alone and 155 (54 males) treated with BD combined with cryotherapy. One month after treatment, compared with the BD group, the total response rate [133 (85.8) vs. 105 (69.1), P < 0.001] and occurrence of restenosis at 1-monthaftertreatment [22 (14.2 %) vs. 47 (30.9 %), P < 0.001] in BD & cryotherapy group were significantly higher; furthermore, the inner diameter of the airway stenosis (8.1 ± 0.9 mm vs. 6.4 ± 1.5 mm, P < 0.001), the cross-sectional area of the airway stenosis (51.6 ± 7.8 mm2 vs. 33.1 ± 11.6 mm2, P < 0.001), FEV1 (5.26 ± 0.42 L vs. 4.32 ± 0.31 L, P < 0.001), and PEF (5.72 ± 0.36 L/s vs. 4.56 ± 0.42 L/s, P < 0.001) in BD & cryotherapy group showed significantly more improvements. Moreover, Pearson's correlation analysis showed significantly strong positive correlation (r = 0.818，P < 0.001) between the cross-sectional area of airway stenosis measured by PS-base image processing technology and the inner diameter of airway stenosis measured by chest CT.

Conclusion

BD combined with cryotherapy for the interventional treatment of CCAS might be superior to BD alone. PS-base image processing technology might be used as a supplement strategy for measuring the degree of central airway stenosis.

Root and canal anatomy of mandibular first molars using micro-computed tomography: a systematic review

BACKGROUND

A thorough understanding of root and canal anatomy is crucial for successful root canal treatment outcomes. This systematic review aims to explore the published micro-CT studies investigated the anatomy of root and canal system in permanent mandibular first molars.

METHOD

An electronic search was performed on Web of science, PubMed, and Scopus. Micro-CT journal studies investigated the root and canal anatomy of permanent double-rooted mandibular first molars were included. Data on study characteristics, objectives of interest, specifications of the studies, and micro-CT specifications were extracted. Risk of bias assessment (ROB) of the included studies was performed using Anatomical Quality Assessment (AQUA) tool. The extracted data were presented in tables and figures to present and synthesise the results. A meta-analysis was performed for the studies related to the prevalence of Vertucci's canal configurations, middle mesial canal (MMC) configurations, and Fan's isthmus types.

RESULTS

Amongst 1358 identified studies, thirty met the inclusion criteria. In terms of the objectives, the selected studies showed high anatomical variability in mandibular first molars. Twenty-two (73%), 25 (83%), and 12 (40%) of the studies reported the population/ethnicity, micro-CT specifications, and ethical approval, respectively. 28 (93%) studies did not disclose the method of sample size estimation. In only 6 (20%) of the studies, the authors had calibrated the assessment approaches. Mostly, a potential ROB was reported in domain 1 (objective(s) and subject characteristics) and domain 3 (methodology characterization). Whilst, low risk was reported in domains 2 (study design), 4 (descriptive anatomy), and 5 (reporting of results). The overall ROB was reported to be ''moderate'' in the vast majority of the studies (27/30). Meta-analysis results showed high levels of heterogeneity among the studies related to MMCs (I² = 86%) and Fan's isthmus (I² = 87%). As for the root canal configuration, pooled prevalence showed that Vertucci type IV and type I were the most prevalent in mesial and distal root canals, respectively.

CONCLUSION

Based on moderate risk of bias level of evidence, micro-CT studies have shown wide range of qualitative and quantitative data presentations of the roots and canals in mandibular first molars. Protocol and registration. The protocol of this systematic review was prospectively registered in the Open Science Framework database ( https://osf.io ) on 2022-06-20 with the registration number 10.17605/OSF.IO/EZP7K.

Effects of root canal enlargement on unprepared areas and coronal dentine thickness of three-rooted maxillary first premolars with different root configurations: a stepwise micro-CT study

AIM

To evaluate the effects of progressive root canal enlargements on the unprepared surface area and remaining dentine thickness of three-rooted maxillary first premolars with different root configurations.

METHODOLOGY

Thirty three-rooted maxillary first premolars with 3 root configurations (n=10) were selected and scanned in a micro-CT device. The root canals were sequentially enlarged with rotary instruments sizes 30.02 (step 1), 30.04 (step 2), and 30.06 (step 3). After each step, a new scan was taken. Analysed parameters included morphometric measurements (length, volume and surface area), number of static voxels, and minimal dentine thickness. Statistic analyses were performed with one-way ANOVA post hoc Tukey tests and paired sample t-test at a significance level of 5%.

RESULTS

No statistical differences were observed among groups regarding the morphometric parameters and static voxels (p > 0.05). The minimal dentine thickness of the distobuccal root significantly changed depending on the root configuration (p < 0.05), while no differences were observed in the other roots (p > 0.05). A great variation in the position of the minimal dentine thickness was observed after preparation. Overall, mean percentage reduction of dentine thickness was higher in the buccal roots than in the palatal root (p < 0.05). In the mesiobuccal and distobuccal root, the number of slices with minimal dentine thickness lower than 0.05 mm increases 2 to 3 times and 3 to 4 times, respectively, from steps 1 to 3.

CONCLUSIONS

Instruments sizes 30.02 and 30.04 can be safely and effectively used to enlarge the buccal and palatal canals of three-rooted maxillary first premolars.

Three-dimensional analysis of coronal root canal morphology of 136 permanent mandibular first molars by micro-computed tomography

Background/purpose

Minimally invasive endodontic approach become a research hotspot and may prevent the fracture of endodontically-treated teeth. This research aims to measure the coronal root canal morphology of permanent mandibular first molars in 3D and propose a new minimally invasive endodontic approach based on this measurement.

Materials and methods

Data of 136 permanent mandibular first molars were involved and reconstructed in 3D models with canals. Then, the morphology characteristics of the coronal root canal were measured.

Results

Overall, the distribution of root canal orifices was more centralized than other landmarks. The landmarks were located more mesiobuccally to the center of the occlusal plane of molars. Specifically, the measurements of the maximum curvature of coronal root canals in the axial direction were: in 3-canals 2-rooted teeth, the average angles of curvatures were 23°,25°,11° for mesiobuccal (MB), mesiolingual (ML) and distobuccal (DB) canals, respectively; in 4-canals 2-rooted teeth were 23°,25°,12°,16°for MB, ML, DB, and distolingual (DL) canals, respectively; in 4-canals 3-rooted teeth were 25°,27°,17°,39° for MB, ML, DB, and DL canals, respectively. The degrees of coronal root canal curvatures in the horizontal direction were: in 3-canals teeth, the average angles of curvatures were −1°,47°,-2° for MB, ML and DB canals, respectively; in 4-canals 2-rooted teeth were −4°,41°,-25°,48° for MB, ML, DB, and DL canals, respectively; in 4-canals 3-rooted teeth were −3°,33°,-43°,79° for MB, ML, DB, and DL canals, respectively.

Conclusion

The results of this study are similar to those previously obtained using CBCT and can help us design endodontic approaches.

Evaluation of the root canal morphology of human teeth by cone beam computed tomography and micro-computed tomographic – A systematic review with meta-analysis

Introduction:

To thoroughly plan and execute any dental treatment, the anatomy of the dental root canals is of prime significance. Hence, in this systemic review, we intend to evaluate the cone beam computed and micro-computed tomographic presentations of the root canal morphologies of the secondary teeth.

Materials and Methods:

We conducted the search for the data from the online sources such as the “EMBASE,” “Pubmed,” “Scopus,” and other sources. Only human studies were collected. Terms searched were cone beam computed tomography (CBCT), micro-computed tomography, permanent teeth, and root canal morphology. The data extraction and meta-analysis were based on the PRISMA guidelines.

Results:

A total of 170 studies were initially considered for the study. After the application of the inclusion and the exclusion criteria, only ten studies were qualified for the study. In 2 studies, the comparison was done between the conical beam and the microtomograhic views for assessing the root canal anatomies. There were, however, three studies that did not conclude any significant relation between the two imaging systems. When the risk of bias was calculated for the ten studies, there were only low and moderate for the ten included studies. The pooled prevalence among the genders were 21.4% (14.0%–24.6% confidence interval [CI] 95%) and 25.3% (20.0%–30.7% CI 95%), respectively, with high heterogeneity values (= 99.30% and 98.50%, respectively), but no statistical significance (P > 0.05).

Conclusion:

Both the imaging systems CBCT and the microtomography can be used with accuracy in the evaluation of the anatomic variations of the human root canal. However, a definition is dependent on the voxel size.

Evaluation of accuracy of fit in cast metal post fabricated with direct and indirect techniques using micro-CT - An in vitro study

Context

Accuracy of fit of cast metal posts fabricated with direct and indirect techniques.

Aims

To evaluate the accuracy of fit of cast metal posts fabricated with direct and indirect techniques using micro-CT.

Materials and Methods

Sixty extracted human maxillary central incisors were used. The teeth were decoronated leaving 2 mm at the cementoenamel junction. Four patterns for each tooth were made including one direct and indirect wax pattern and one direct and indirect resin pattern. In total, 240 patterns and castings were made. Each tooth was scanned using microcomputed tomography (μCT) system with a resolution of 14.5 μm. μCT analyzer Sky scanner software was used to calculate the volume of space between the post and the canals. Statistical analysis used: The student paired t-test and unpaired t-test were used to determine the significant differences between groups.

Results

The overall space between the canal walls and posts made with the direct wax and resin technique had an average mean value of 1.10 mm³, whereas with the indirect technique resin and wax pattern, the average mean was 1.30 mm³ which was significant.

Conclusion

Within the limitations of the study, it was found that the accuracy of fit is better in direct technique using wax pattern.

Comparison of limited- and large-volume cone-beam computed tomography using a small voxel size for detecting isthmuses in mandibular molars

Purpose

This study was performed to compare the ability of limited- and large-volume cone-beam computed tomography (CBCT) to display isthmuses in the apical root canals of mandibular molars.

Materials and Methods

Forty human mandibular first molars with isthmuses in the apical 3 mm of mesial roots were scanned by micro-computed tomography (micro-CT), and their thickness, area, and length were recorded. The samples were examined using 2 CBCT systems, using the smallest voxels and field of view available for each device. The Mann-Whitney, Friedman, and Dunn multiple comparison tests were performed (α=0.05).

Results

The 3D Accuitomo 170 and i-Cat devices detected 77.5% and 75.0% of isthmuses, respectively (P>0.05). For length measurements, there were significant differences between micro-CT and both 3D Accuitomo 170 and i-Cat (P<0.05).

Conclusion

Both CBCT systems performed similarly and did not detect isthmuses in the apical third in some cases. CBCT still does not equal the performance of micro-CT in isthmus detection, but it is nonetheless a valuable tool in endodontic practice.

Evaluation of Palatal Furcation Groove and Root Canal Anatomy of Maxillary First Premolar: A CBCT and Micro-CT Study

Objectives

This study is aimed at investigating the root and root canal morphology by cone beam computed tomography (CBCT) and palatal furcation groove of the buccal root by microcomputed tomography (micro-CT) of maxillary first premolars in a Chinese subpopulation.

Methods

This study assessed CBCT images of 440 patients aged 14-80 years. Based on Vertucci's classification, the number of roots and the canal configuration were determined. Forty-eight maxillary first premolars with furcation grooves were analyzed by micro-CT in patients aged 18-25 years.

Results

Based on the CBCT assay, 70.22% and 29.32% of maxillary first premolars were 1 root and 2 roots, respectively. The configuration indicated statistical difference (P < 0.05) between male and female patients. The most common canal type was type IV and was found in 44.32% of cases, followed by type I in 27.84%, and then type II in 20.57%. Root bifurcations had 40.13% prevalence which was distributed more in the middle third than in the cervical and the apical third. For the micro-CT study, 95.83% of the furcation groove configuration was found in the bifurcated maxillary first premolars. The length varied from 1.02 to 7.63 mm. The mean depth of this groove was 0.57 mm in the root coronal, 0.47 mm in the root middle, and 0.22 mm in the root apical level. Palatal dentin width was smaller than 1 mm.

Conclusion

The anatomy of the root and root canal system and the irregular wall width of maxillary first premolars with furcation grooves may help dentists to understand the anatomical morphology and improve the outcomes of endodontic treatment.

Cone-beam and micro-computed tomography for the assessment of root canal morphology: a systematic review

This study presents an overview of the accuracy of cone beam computed tomography (CBCT) compared with micro-computed tomography (μCT) in the assessment of root canal morphology of extracted human permanent teeth. A database search in PubMed, PubMed Central, Embase, Scopus, Opengrey, Scielo and Virtual Health Library was conducted which compared root canal morphology of extracted human permanent teeth on the accuracy of CBCT with μCT. In accordance with PRISMA statement guidelines, data were extracted on study characteristics, target mediators, sampling and assay techniques and the parameters associated with obtaining the image and ability to identify the root canal morphology. Amongst 2734 records, ten fulfilled the inclusion criteria. Four studies compared the accuracy of CBCT and μCT in the assessment of root canal morphology using Vertucci's classification, with at least one CBCT group or subgroup of each study presented high agreement compared to the μCT. Six studies assessed more detailed root canal morphology, including two articles that found a lack of agreement between these imaging systems. Risk of bias was deemed low in three studies, moderate in four and high in three. CBCT can be as accurate as μCT in the assessment of several morphological features of extracted human permanent teeth; however there are some exceptions related to the more detailed morphological aspects. Voxel size likely influences the ability to detect these features, though the different aspects of exposure setting used in studies components may be confounding factors. CBCT may be considered for the assessment of root canal morphology ex-vivo.

Canal transportation and centering ratio after preparation in severely curved canals: analysis by micro-computed tomography and double-digital radiography

OBJECTIVES

This study compared canal transportation and centering ratio produced after instrumentation with a single heat-treated reciprocating system, WaveOne Gold (WOG; Dentsply Sirona, Tulsa, OK, USA) and a single heat-treated rotary instrument, XP-endo Shaper (XPS; FKG, La Chaux-de-Fonds, Switzerland), using micro-computed tomographic (micro-CT) imaging, and evaluated the ability of double-digital radiography (DDR) to detect canal transportation.

MATERIALS AND METHODS

Mesial root canals of mandibular molars with severe curvature (25-70°) were randomly assigned to either WOG or XPS groups for preparation. Centering ratio was measured by micro-CT imaging, while canal transportation was measured by micro-CT and DDR methods at 3, 5, and 7 mm from the apex. Data were statistically compared between groups using the t test (α = 5%).

RESULTS

The micro-CT method showed that XPS's shaping ability regarding the centering ability (P = 0.030) and canal transportation (P = 0.028) was significantly better than WOG only at the 7-mm level. The DDR technique detected no difference in canal transportation between groups at any level (P > 0.05); however, a significant difference between evaluation methods was detected at the 5-mm level in the WOG group (P = 0.023).

CONCLUSIONS

Micro-CT technique revealed a significantly better centering ability and less canal transportation with XPS compared to WOG. The DDR technique was not capable of detecting the significant difference between the tested groups.

CLINICAL RELEVANCE

Root canal curvatures may lead to procedural errors during endodontic treatment. Thus, differences on the shaping ability of single heat-treated reciprocating and rotary systems should be known.

Three-rooted maxillary first premolars incidentally detected on cone beam CT: an in vivo study

PURPOSE

To explore the incidence and analyze the morphology of three-rooted maxillary first premolars (MFPs) incidentally detected on cone beam computed tomography (CBCT) scans.

METHODS

Of 1328 patients who underwent CBCT scans of the maxilla, only patients with three-rooted MFPs were selected. Morphological features, including the lengths and diameters of palatal, mesiobuccal (MB) and distobuccal (DB) roots, the positions of bucco-palatal (B-P) bifurcations, the distances between root canal bifurcations and cementoenamel junctions (CEJs) and the distances between the apical thirds of the roots, were measured. The canal configuration and the visibility of root canals were also evaluated.

RESULTS

A total of 16/1328 (1.2%) patients had one or two three-rooted MFPs, and a total of 22/2656 (0.8%) three-rooted MFPs were enrolled. The lengths and diameters of palatal roots were significantly greater than those of other roots. The positions of B-P bifurcations were located mainly at the middle third of the root. The median distances between root canal bifurcations and CEJs were 3 mm for B-P bifurcations and 5.2 mm for MB-DB bifurcations. The distance between MB and DB roots was significantly shorter than the distances between other root pairs. All teeth had a type VIII canal configuration. Palatal roots exhibited the best visibility of root canals, whereas the worst visibility was observed within DB roots. A gender-related relationship was observed only for the lengths of the roots.

CONCLUSIONS

The occurrence of three-rooted MFPs is not unusual; therefore, preoperative CBCT evaluation could be suggested whenever endodontic procedures are planned on an MFP.

A new methodology for the measurement of the root canal curvature and its 3D modification after instrumentation

OBJECTIVE

In this study, the three-dimensional (3D) modification of root canal curvature was measured, after the application of Reciproc instrumentation technique, by using cone beam computed tomography (CBCT) imaging and a special algorithm developed for the 3D measurement of the curvature of the root canal.

MATERIALS AND METHODS

Thirty extracted upper molars were selected. Digital radiographs for each tooth were taken. Root curvature was measured by using Schneider method and they were divided into three groups, each one consisting of 10 roots, according to their curvature: Group 1 (0°-20°), Group 2 (21°-40°), Group 3 (41°-60°). CBCT imaging was applied to each tooth before and after its instrumentation, and the data were examined by using a specially developed CBCT image analysis algorithm.

RESULTS

The instrumentation with Reciproc led to a decrease of the curvature by 30.23% (on average) in all groups.

CONCLUSIONS

The proposed methodology proved to be able to measure the curvature of the root canal and its 3D modification after the instrumentation.

Radiographic and micro-computed tomography classification of root canal morphology and dentin thickness of mandibular incisors

Context:

Root canal anatomy is evaluated using different methodologies.

Aims:

The aim of this study is to evaluate and classify root canal morphology and dentin thicknesses (DT), comparing radiographic and micro-computed tomography (CT) analysis.

Materials and Methods:

Canal diameter and DT of mandibular incisors (n = 520) were evaluated using digital radiographs in buccolingual (BL) and mesiodistal (MD) directions. The diameter ratio (DR) BL/MD was classified: flattened (FL, DR >4); oval (OV, 2≤ DR ≥4); rounded (RN, 1.1< DR >2); round (RO, 0.9≤ DR ≥1.1); and with BL flatness (BL, DR <0.9). OV (n = 110) were subjected to micro-CT. DT and DR were evaluated at 3, 6, and 9 mm. ANOVA, Tukey, and paired Wilcoxon tests (P < 0.05) were used.

Results:

Radiographic classification was 23.3% FL, 41.3% OV, 27.3% RN, 4.5% RO, and 3.6% BL. DT was similar. Radiographic DT at 3 and 9 mm was greater than micro-CT (P < 0.05) and was similar at 6 mm (P > 0.05). DR differed between the analyses. Oval canals were predominant at all levels radiographically and at 9 and 6 mm in micro-CT analysis, with greater variation at 3 mm.

Conclusion:

Oval root canals are predominant in mandibular incisors at 9 mm. Radiographic DT is larger than observed in micro-CT at 3 and 9 mm, and the classification differed in each root level. The classification at 9 mm is indicated.

Maxillary first premolars with three root canals: two case reports

It is very important that the dentists have sufficient information about possible variations in the expected root canal configurations in order to achieve success in endodontic treatment. In addition to having adequate knowledge on the variations of the root canal anatomy, periapical radiographs from different angles, careful examination of the pulp chamber floor, and use of dental operation microscope during the procedure are also important factors that contribute to the diagnosis of the additional roots and canals. The aims of this article are to present the diagnostic approach and root canal treatments of two maxillary first premolar teeth with three canals in two patients.

Accuracy of cast posts fabricated by the direct and the indirect techniques

STATEMENT OF PROBLEM

Patterns for custom cast posts and cores can be fabricated either by the direct or the indirect technique. Which technique is more accurate is unknown.

PURPOSE

The purpose of this in vitro study was to investigate the effect of pattern fabrication technique on the accuracy of post fit.

MATERIAL AND METHODS

Ten intact extracted premolar teeth with a single canal and similar dimensions received root canal treatment. The teeth were sectioned 2 mm above the cementoenamel junction. A total of 20 cast post and core patterns, 2 for each tooth, were fabricated, 10 with the direct technique and 10 with the indirect technique. Patterns were cast to produce 20 cast post and cores. Each tooth was scanned using a microcomputed tomography (μCT) system with a resolution of 14.5 μm, once with the post of the direct technique and once with the post of the indirect technique. Ct analyzer software was used to calculate the overall space between the post and canal walls and the space areas in 3 different standardized sections. The Student paired t test was used to determine any significant difference in the scores of the groups.

RESULTS

The overall space between the canal walls and posts made with the direct technique ranged between 7.86 and 17.39 mm(3), with a mean value of 12.25 mm(3), whereas with the indirect technique, the space ranged between 6.68 and 18.02 mm(3), with a mean of 11.92 mm(3). No significant differences were found between the results of either technique (P>.05).

CONCLUSIONS

Within the limitations of this study, neither the indirect nor direct pattern fabrication technique influenced the accuracy of post fitting.

Comparative accuracy of the Clearing Technique, CBCT and Micro-CT methods in studying the mesial root canal configuration of mandibular first molars

AIMS

To compare the accuracy of the clearing technique and cone beam computed tomography (CBCT) in the assessment of root canal configurations using micro-computed tomography (micro-CT) imaging system as the reference standard.

METHODOLOGY

Thirty-two mesial roots of mandibular first molars, selected on the basis of micro-CT scans (voxel size: 19.6 μm) and presenting several canal configurations, were evaluated using 2 CBCT scanners (voxels sizes: 120 μm and 150 μm) followed by the clearing technique. Two examiners analysed the data from each method and classified the anatomical configuration of the mesial canal according to Vertucci's system. Data were compared using Fisher's exact and chi-square tests. Reliability for each assessment was verified by the kappa test, and significance level was set at 5%.

RESULTS

Kappa value indicated a high level of agreement between the examiners. Detection of type I configurations was significantly lower in cleared teeth (P < 0.05), whilst type II root canals were detected in all specimens by both tests (P > 0.05). In mesial roots with variable anatomical configurations, CBCT and the clearing method were significantly less accurate than the reference standard (P < 0.05).

CONCLUSION

Within the tooth population studied, accuracy of identifying mesial root canal configuration was influenced greatly by the evaluation method and the type of anatomy. Detection of type I configurations in cleared teeth was significantly lower, whilst type II configurations were detected in all specimens by both methods. In mesial roots with variable anatomical configurations, neither CBCT nor clearing methods were accurate for detecting the actual root canal anatomy.

Tomographic imaging of fragmented cortical bone heteroimplant and methylmethacrylate in segmental bone defect of rabbit tibia

PURPOSE

To evaluate the performance of composites consisting of fragmented cortical bone heteroimplant in association with methylmethacrylate preserved in 98% glycerin, in segmental bone defect of rabbit tibia medial metaphysis.

METHODS

In this study were used twelve adult New Zealand rabbits, divided into three groups of four animals each: G30 (30 days), G60 (60 days) and G90 (90 days). The bone defects previously created in the tibia were filled with composites and both were evaluated by cone-beam computed tomography, immediately after surgery and after 30, 60, and 90 days.

RESULTS

The composites fulfilled and remained in the sites of bone defects in all cases and were not registered signals of infection, migration or rejection.

CONCLUSIONS

The implanted composites promoted the bone defects repair without signals of infection and/or rejection. The composites are one more option for bone defects repair.

Location of the mandibular canal and thickness of the occlusal cortical bone at dental implant sites in the lower second premolar and first molar

The objective of this study was to evaluate the location of the mandibular canal and the thickness of the occlusal cortical bone at dental implant sites in the lower second premolar and lower first molar by using dental cone-beam computed tomography (CBCT). Seventy-nine sites (47 second premolar and 32 first molar sites) were identified in the dental CBCT examinations of 47 patients. In this study, 4 parameters were measured: (1) MC—the distance from the mandibular canal to the upper border of the mandible; (2) CD—the distance from the mandibular canal to the buccal border of the mandible; (3) MD—the distance from the mandibular canal to the lingual border of the mandible; (4) TC—the thickness of the cortical bone at the occlusal side. A statistical analysis was employed to compare the size and differences between these 4 parameters at the lower second premolar and lower first molar. Regarding the MC and MD, the experimental results showed no statistical difference between the first molar and second premolar. However, the TC for the second premolar was greater than that of the first molar. Thus, careful consideration is necessary in choosing the size of and operation type for dental implants.