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.

Classification of periodontal biotypes with the use of CBCT. A cross-sectional study.

OBJECTIVES: The aim of this study is to investigate the relationship between periodontal morphometric parameters and to develop a biotype classification based on the variables examined with the use of cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Forty-two periodontally healthy subjects that underwent a CBCT examination as part of a different diagnostic procedure participated in the study. Measurements were performed on sectional images and included gingival thickness and labial bone plate thickness midbuccally, crown width to crown length ratio, bone crest to the CEJ distance and bone crest to the gingival margin distance midbuccally, and at the approximal aspects of 186 maxillary anterior teeth. RESULTS: Gingival thickness at the level of CEJ was positively correlated with labial bone plate thickness and crown form. Crown form was not correlated with labial bone plate thickness. Cluster analysis supported the existence of four periodontal biotypes, "thin," "thick," "average," and "mixed." Labial bone plate thickness was thinner than 1 mm at 70 % of the measured sites. CONCLUSIONS: Only 50 % of the teeth belonged to thin or thick biotype. The other 50 % of the teeth belonged to the average cluster or presented mixed characteristics. Assessment of labial bone plate thickness based on periodontal biotype should be made with caution. CLINICAL RELEVANCE: Taking into consideration the characteristics of periodontal biotypes enables the clinician to avoid complications in periodontology, prosthetic dentistry, implant dentistry in the esthetic zone, and orthodontics.

Cherubism: a case report of a three-generation inheritance and literature review.

Cherubism is a rare, non-neoplastic pathologic entity first described by Jones in 1933. It affects mostly younger individuals and is usually inherited. Cherubism presents as a painless jaw enlargement that affects both the maxilla and the mandible and is characterized by replacement of the osseous tissue by fibrous connective tissue. Radiologically, the lesions appear as multiple, multilocular radiolucent spaces with distinct borders divided by bony septations, which often dramatically alter the shape and size of the jaw structures. These often result in marked facial abnormalities. Cervical lymphadenopathy is not uncommon in those affected. The disease is self-limited and can reverse itself with time. Approximately 250 cases have been reported in published studies, mostly affecting males. The purpose of our report was to present a case of cherubism diagnosed in a young girl and the long-term (3 generations) follow-up evaluation of her mother and grandmother, both of whom had been diagnosed with the same pathologic entity.

Frequency and Clinical Significance of Incidental Findings on CBCT Imaging: a Retrospective Analysis of Full-Volume Scans.

Objectives: This retrospective study aims to identify incidental findings in cone-beam computed tomography scans of patients irradiated for preoperative evaluation for implant placement and obtained using the same imaging unit as well as the same field of view. The incidence of each incidental finding, as well as the overall incidence, were calculated and the findings were ranked according to their clinical significance. Material and Methods: A total of 741 cone-beam computed tomography (CBCT) examinations with extended field of view (15 x 15 cm) were retrospectively evaluated for incidental findings (IFs). These were identified, recorded, classified as to their location, and ranked according to their clinical significance. Results: The vast majority of CBCT examinations presented at least one IF, resulting in a surprisingly high prevalence in total. If extreme anatomical variants are considered (nasal septum deviation, sinus septations etc.), the cumulative prevalence exceeds 99%. IFs of major significance, that may require immediate attention, are beyond 10% in frequency. Conclusions: We found high prevalence of incidental findings on cone-beam computed tomography examinations performed for preoperative evaluation for implant placement (99.5% if anatomical variants included). Most incidental findings were of minor significance. Although the number of incidental findings that require immediate attention is relatively low, there is a considerable number of cases that need periodic evaluation and/or referral.

Evaluation of Bitemark Analysis's Potential Application in Forensic Identification: A Systematic Review.

Bitemark analysis involves the examination of both patterned injuries and contextual circumstances, combining morphological and positional data. Considering the uniqueness of human dentition, bitemarks caused by teeth on skin or impressions on flexible surfaces could assist in human identification. AIMS: to investigate the available literature systematically and evaluate the scientific evidence published over the past decade concerning the potential application of bitemark analysis in forensic identification. METHODS: Two researchers meticulously searched electronic databases from January 2012 to December 2023, including Scopus, PubMed, Web of Science, and the Cochrane Library. Adhering to the PRISMA statement guidelines, this review employed appropriate medical subject headings (MeSHs) and free-text synonyms. Strict inclusion and exclusion criteria were applied during article retrieval. RESULTS: The findings yielded controversial outcomes. Approximately two-thirds of the articles concluded that bitemark analysis is useful in forensic identification, while the remaining articles did not report statistically significant outcomes and cautioned against relying solely on bitemark analysis for identification. CONCLUSIONS: The authors assert that bitemark analysis can be a reliable and complementary method for forensic identification, contingent upon the establishment and adoption of a universally accepted global protocol for data collection, processing, and interpretation. Undoubtedly, recent years have witnessed a notable increase in research focused on bitemark identification, driven by the goal of achieving quantitative, objective, reproducible, and accurate results.

Evaluation of anatomical variants and pathological findings of the maxillary sinus prior to sinus floor elevation: A Cone Beam CT retrospective study in 660 patients.

Background: Maxillary sinuses may present a wide spectrum of anatomical variations and pathological lesions whose recognition is mandatory for the clinician, especially prior to any surgical intervention in the area, such as in cases of sinus floor elevation. The goal of this study was the evaluation, mapping and prevalence of sinus anatomical variants and pathoses in Cone Beam Computed Tomography (CBCT) scans of dental patients. Material and Methods: 660 CBCT examinations of adult patients involving both sinuses were obtained (between 2017 and 2023) and analyzed. The following anatomic variants and pathologic findings were evaluated: antral septa (AS), posterior superior alveolar artery (PSAA), sinus hypoplasia, sinusitis, odontogenic cysts, retention cysts, antroliths, and various less common lesions (e.g.: benign fibro-osseous dysplastic lesions, neoplasms etc.). Investigation of the association of the findings with patients' age and gender was performed using the Chi-square test (X2), Fisher's exact test, t-test, and ANOVA (P<0.05). Differences in prevalence between findings, based on their location (right and/or left sinus), were investigated using z-test and t-test. Results: AS were found in 38.6%, and PSAA was identifiable in 90.2% (mean distance from the sinus floor=6.44 mm) of the patients respectively. 3% of patients had hypoplasia, 15.6% sinusitis, 2.7% odontogenic cysts, 16.1% retention cysts, 8.6% antroliths, and 1.7% uncommon lesions (e.g. malignant neoplasms and fibrous dysplasia). A statistically significant association was found between gender and PSAA diameter, PSAA distance from the sinus floor, hypoplasia, sinusitis, and retention cysts, as well as a statistically significant association between age and PSSA diameter and sinusitis. Conclusions: The prevalence of various anatomical variants and pathologic findings of the maxillary sinus did not differ based on their location. However, some of these findings appear to be related to either gender or age. CBCT is a valuable diagnostic tool to identify various anatomical variants and pathological findings of the maxillary sinus. Key words:Sinus, anatomy, pathology, CBCT.

Multidimensional 3D-Printed Scaffolds and Regeneration of Intrabony Periodontal Defects: A Systematic Review.

BACKGROUND: The utilization of regenerative techniques in periodontology involves tailoring tissue engineering principles to suit the oral cavity's unique environment. Advancements in computer-assisted technology, specifically utilizing cone beam computed tomography (CBCT), enabled the fabrication of 3D-printed scaffolds. The current review aims to explore whether 3D-printed scaffolds are effective in promoting osteogenesis in patients with periodontal defects. METHODS: A thorough exploration was undertaken across seven electronic databases (PubMed, Scopus, ScienceDirect, Google Scholar, Cochrane, Web of Science, Ovid) to detect pertinent research in accordance with specified eligibility criteria, aligning with the PRISMA guidelines. Two independent reviewers undertook the screening and selection of manuscripts, executed data extraction, and evaluated the bias risk using the Newcastle-Ottawa Scale for non-randomized clinical trials and SYRCLE's risk of bias tool for animal studies. RESULTS: Initially, 799 articles were identified, refined by removing duplicates. After evaluating 471 articles based on title and abstract, 18 studies remained for full-text assessment. Eventually, merely two manuscripts fulfilled all the eligibility criteria concerning human trials. Both studies were prospective non-randomized clinical trials. Moreover, 11 animal studies were also included. CONCLUSIONS: The use of multidimensional, 3D-printed, customized scaffolds appears to stimulate periodontal regeneration. While the reported results are encouraging, additional studies are required to identify the ideal characteristics of the 3D scaffold to be used in the regeneration of periodontal tissue.

The Role of Cone Beam Computed Tomography in Periodontology: From 3D Models of Periodontal Defects to 3D-Printed Scaffolds.

The treatment of osseous defects around teeth is a fundamental concern within the field of periodontology. Over the years, the method of grafting has been employed to treat bone defects, underscoring the necessity for custom-designed scaffolds that precisely match the anatomical intricacies of the bone cavity to be filled, preventing the formation of gaps that could allow the regeneration of soft tissues. In order to create such a patient-specific scaffold (bone graft), it is imperative to have a highly detailed 3D representation of the bone defect, so that the resulting scaffold aligns with the ideal anatomical characteristics of the bone defect. In this context, this article implements a workflow for designing 3D models out of patient-specific tissue defects, fabricated as scaffolds with 3D-printing technology and bioabsorbable materials, for the personalized treatment of periodontitis. The workflow is based on 3D modeling of the hard tissues around the periodontal defect (alveolar bone and teeth), scanned from patients with periodontitis. Specifically, cone beam computed tomography (CBCT) data were acquired from patients and were used for the reconstruction of the 3D model of the periodontal defect. The final step encompasses the 3D printing of these scaffolds, employing Fused Deposition Modeling (FDM) technology and 3D-bioprinting, with the aim of verifying the design accuracy of the developed methodοlogy. Unlike most existing 3D-printed scaffolds reported in the literature, which are either pre-designed or have a standard structure, this method leads to the creation of highly detailed patient-specific grafts. Greater accuracy and resolution in the macroarchitecture of the scaffolds were achieved during FDM printing compared to bioprinting, with the standard FDM printing profile identified as more suitable in terms of both time and precision. It is easy to follow and has been successfully employed to create 3D models of periodontal defects and 3D-printed scaffolds for three cases of patients, proving its applicability and efficiency in designing and fabricating personalized 3D-printed bone grafts using CBCT data.

CBCT-Based Design of Patient-Specific 3D Bone Grafts for Periodontal Regeneration.

The purpose of this article is to define and implement a methodology for the 3D design of customized patient-specific scaffolds (bone grafts) for the regeneration of periodontal tissues. The prerequisite of the proposed workflow is the three-dimensional (3D) structure of the periodontal defect, i.e., the 3D model of the hard tissues (alveolar bone and teeth) around the periodontal damage, which is proposed to be generated via a segmentation and 3D editing methodology using cone beam computed tomography (CBCT) data. Two types of methodologies for 3D periodontal scaffold (graft) design are described: (i) The methodology of designing periodontal defect customized block grafts and (ii) the methodology of designing extraction socket preservation customized grafts. The application of the proposed methodology for the generation of a 3D model of the hard tissues around periodontal defects of a patient using a CBCT scan and the 3D design of the two aforementioned types of scaffolds for personalized periodontal regenerative treatment shows promising results. The outputs of this work will be used as the basis for the 3D printing of bioabsorbable scaffolds of personalized treatment against periodontitis, which will simultaneously be used as sustained-release drug carriers.

Contribution of Morphology of Frontal Sinuses (Linear and Volumetric Measurements) to Gender Identification Based on Cone Beam Computed Tomography Images (CBCT): A Systematic Review.

Human identification is considered as an important step in the reconstruction of biological profiles, especially of unknown individuals. Frontal sinuses (FS) have been regarded as an ideal anatomical structure for individualisation because few pathological conditions can potentially alter their shape. AIM: The aim of this review was to evaluate scientific evidence published since January 2010 and determine whether the dimensions and volume of FS might be useful parameters for gender determination and human identification, based only on cone beam computed tomography images (CBCT). METHODS: This review was performed in accordance with the PRISMA statement. Four databases were searched for articles published between January 2010 and June 2022. RESULTS: A total of 195 records were initially identified, and 90 remained after a manual duplicate check. Eight articles were selected for a full review according to the inclusion and exclusion criteria after title and abstract screening. A total of 718 participants (359 males and 359 females) were identified from the included studies. Frontal sinus volume (FSV) was significantly higher in male individuals. Frontal sinus height (FSH) and volume were the superior discriminating parameters for forensic identification. CONCLUSIONS: This review demonstrates that assessment of FS based on CBCT images could be beneficial for gender identification in forensic science. According to the obtained studies, frontal sinus volume (FSV) and frontal sinus height (FSH) are significant greater in males than in females, providing an additional complementary method. Larger sample size and common measurement protocols are needed to verify their usefulness.

Gender Determination Based on CBCT Maxillary Sinus Analysis: A Systematic Review.

Gender determination is an essential element for human identification in forensic medicine, to which the maxillary sinuses may contribute as they remain intact even after severe damage to the skull and other structures. AIM: To evaluate scientific evidence published over the last decade to determine whether maxillary sinus dimensions and volume may constitute useful parameters for forensic identification and gender determination, based only on cone-beam computed tomography images (CBCT). METHODS: This review adhered to the PRISMA statement's criteria. Four databases were searched for articles published between January 2010 and April 2023. RESULTS: Initially, 1719 records were identified. After screening, there were 2475 participants in the included studies. Of the fifteen articles selected, five reported data assessing only volumetric measurements of the maxillary sinus, seven reported data calculating only linear measurements and three reported data by combining findings of both linear and volumetric measurements of the maxillary sinus. Maxillary sinus volume was significantly higher in male participants. Maxillary sinus height was the best discriminating parameter for forensic identification with an overall accuracy ranging from 70% to 80%. CONCLUSIONS: Maxillary sinus measurements revealed anatomic variability between genders, and this approach can be applied as a complementary method for human identification.

Three-Dimensional Cone-Beam Computed Tomography Evaluation of Changes in Naso-Maxillary Complex Associated with Rapid Palatal Expansion.

The introduction of Cone-Beam Computed Tomography (CBCT) in orthodontics has added a new tool to diagnosis and treatment planning. The aim of this prospective clinical trial was to investigate the changes in the dimensions of the naso-maxillary complex in growing patients after RPE using CBCT. A total of 16 growing children (8 females, 6 males) with a mean age of 11, 12 ± 1 and 86 years underwent RPE as part of their comprehensive orthodontic treatment. CBCT scans were obtained before RPE (T1), immediately after RPE (T2) and 6 months after RPE (T3). The dimensions of the nasal width, nasal floor and the aperture of the midpalatal suture were calculated in different coronal slices of CBCT. Evaluation of the mean value variance per measurement at the three time intervals were performed using the paired Wilcoxon signed-rank test. Differences between the three time intervals were assessed by performing Multiple Pairwise Comparisons. A statistically significant increase in all measurements was seen immediately after RPE expansion (T2-T1) and six months after expansion (T3-T1). Between the end of expansion and 6 months in retention (T3-T2), a decrease was observed for all measurements. RPE can cause expansion of the nasal cavity in growing patients. The expansion of the midpalatal suture follows a triangular pattern of opening.

Oral Squamous Cell Carcinoma (OSCC) Imitates Denosumab-Induced Osteonecrosis of the Mandibular Alveolus: A Diagnostic Challenge.

Oral squamous cell carcinoma (OSCC) may arise in the the alveolar ridge (in a minority of cases). Smoking, chronic mucosal injuries, and poor oral hygiene are involved in its pathogenesis. It mostly occurs to men instead of women and affects the mandible on a 3:2 ratio to the maxilla. The objective of the current study is to present an interesting case of an OSCC of the alveolar ridge mimicking jaw osteonecrosis due to denosumab, resulting in differential diagnostic dilemmas. A 78-year-old female patient, edentulous and bearing total dentures, was referred with a persistent (four months), severely painful, ulcerative lesion in the anterior lateral (right) region of the residual alveolar ridge of the mandible. Medical history referred to a long-term systemic steroid use due to sarcoidosis as well as the subcutaneous use of denosumab for osteoporosis one/month for one year. Cone-beam CT (CBCT) examination was performed where bone resorption was detected and a differential diagnosis of osteonecrosis of the jaws (ONJs) from denosumab or neoplasia was made. A biopsy was carried out, and the histological examination showed that soft tissues and underlying bone were infiltrated by abnormal, confluent, compact islands of malignant squamous cells with intense atypia and numerous mitoses indicating a moderately differentiated OSCC. Denosumab inhibits the binding of receptor activator of nuclear factor ligand (RANKL) to receptor activator of nuclear factor-kappa (RANK); this decreases bone resorption and results in increased bone density. However, denosumab may induce ONJ. The area of exposed bone and abnormal soft tissue alterations may resemble both benign and malignant diseases. Osteonecrosis may mimic OSCC or may even provide the suitable substrate for the development of OSCC. Biopsy as well as bone imaging examination are required to accurately determine the possibility of neoplastic formation and its boundaries in cases of osteonecrosis especially in patients under treatment with denosumab or bisphosphonate-related ONJ (BRONJ).

Morphological Assessment of Nasopalatine Canal Using Cone Beam Computed Tomography: A Retrospective Study of 124 Consecutive Patients.

This study aimed to assess and analyze the morphology and dimensions of the nasopalatine canal (NPC), as well as the adjacent buccal osseous plate (BOP), and to investigate the effect of gender, edentulism, NPC types, absence of maxillary central incisors (ACI) and age on the NPC and BOP, using cone beam computed tomography (CBCT). A total of 124 CBCT examinations (67 female and 57 male patients) were retrospectively included and evaluated. The assessment of the dimensions of the NPC, as well as the dimensions of the adjacent BOP, was performed by three Oral and Maxillofacial Radiologists on reconstructed sagittal and coronal CBCT sections under standardized conditions. Regarding the dimensions of the NPC and the adjacent BOP, the mean values were significantly higher among males than females. Furthermore, edentulous patients showed a significant reduction in BOP dimensions. Additionally, NPC types showed a significant effect on the length of the NPC, and the ACI had a significant effect on reducing BOP dimensions. Age had a significant effect on the diameter of the incisive foramen, with the mean values generally increasing with an increasing age. CBCT imaging of this anatomical structure contributes significantly to its full assessment.

Scattered Radiation Distribution Utilizing Three Different Cone-Beam Computed Tomography Devices for Maxillofacial Diagnostics: A Research Study.

This study aimed to estimate scattered radiation and its spatial distribution around three cone-beam computed tomography (CBCT) devices, in order to determine potential positions for an operator to stand if they needed to be inside the CBCT room. The following devices were tested: Morita Accuitomo (CBCT1), Newtom Giano HR (CBCT2), Newtom VGi (CBCT3). Scattered radiation measurements were performed using different kVp, mA, and Field of View (FOV) options. An anthropomorphic phantom (NATHANIA) was placed inside the X-ray gantry to simulate clinical conditions. Scattered measurements were taken with the Inovision model 451P Victoreen ionization chamber once placed at fixed distances from each irradiation isocenter, away from the primary beam. A statistically significant (p < 0.001) difference was found in the mean value of the scattered radiation estimations between the CBCT devices. Scattered radiation was reduced with a different rate for each CBCT device as distance was increased. For CBCT1 the reduction was 0.047 µGy, for CBCT2 it was 0.036 µGy, and for CBCT3 it was 0.079 µGy, for every one meter from the X-ray gantry. Therefore, at certain distances from the central X-ray, the scattered radiation was below the critical level of 1 mGy, which is defined by the radiation protection guidelines as the exposure radiation limit of the general population. Consequently, an operator could stay inside the room accompanying the patient being scanned, if necessary.

Radiologic findings of osteonecrosis, osteoradionecrosis, osteomyelitis and jaw metastatic disease with cone beam CT.

PURPOSE: The purpose of this study was to assess CBCT scans of patients with medication related osteonecrosis of the jaws (MRONJ), osteoradionecrosis (ORN), osteomyelitis (OM) and jaw metastatic disease (JM), evaluate the presence and extent of radiologic findings, identify radiologic parameters that may distinguish the four entities and last, introduce a new modified radiographic index (CRIm), in order to contribute to the diagnosis of these conditions. METHODS: Τwo major databases were retrospectively searched for fully documented and diagnosed CBCT scans of MRONJ, ORN, OM and JM from 2006 to 2019. 335 CBCT scans met the inclusion criteria and were assessed under standardized viewing conditions blindly by 2 observers. The CRIm index proposed in this study evaluates: lytic changes, sclerosis, periosteal bone formation, sequestration, non-healing extraction sockets and other findings which included: sinus implication, inferior alveolar canal implication and jaw fracture. Lytic changes, sclerosis, periosteal bone formation, sequestration and non-healing extraction sockets were scored as: absent (0), localized/single (1) and extensive/multiple (2). Each one of other findings were scored individually as: absent (0) and present (1). For statistical analysis t-test, Pearson's r correlation coefficient, one-way ANOVA and Bonferonni were performed. RESULTS: Extensive lytic changes were the most common finding, especially for ORN, where it occurred in all CBCT scans (100%). The mean value of the CRIm index differs significantly between CBCT scans with MRONJ and JM, as well as between those with OM and JM (Bonferroni p < 0.001). CONCLUSIONS: The new modified Composite Radiographic Index introduced in this study, appears to have improved an objective approach to the previously used Composite Radiographic Index by means of cumulative radiologic features. Τhe predominance of certain radiologic features in one or more of these entities may lead the diagnostician towards the correct diagnosis.

Evaluation of 3D Modeling Workflows Using Dental CBCT Data for Periodontal Regenerative Treatment.

The cone beam computed tomography (CBCT) technology is nowadays widely used in the field of dentistry and its use in the treatment of periodontal diseases has already been tackled in the international literature. At the same time, advanced segmentation methods have been introduced in state-of-the-art medical imaging software and well-established automated techniques for 3D mesh cleaning are available in 3D model editing software. However, except for the application of simple thresholding approaches for the purposes of 3D modeling of the oral cavity using CBCT data for dental applications, which does not yield accurate results, the research that has been conducted using more specialized semi-automated thresholding in dental CBCT images using existing software packages is limited. This article aims to fill the gap in the state-of-the-art research concerning the usage of CBCT data for 3D modeling of the hard tissues of the oral cavity of patients with periodontitis using existing software tools, for the needs of designing and printing 3D scaffolds for periodontal regeneration. In this context, segmentation and 3D modeling workflows using dental CBCT data that belong to a patient with periodontitis are evaluated, comparisons between the 3D models of the teeth and the alveolar bone generated through the experiments that yielded the most satisfactory results are made, and an optimal and efficient methodology for creating 3D models of teeth and alveolar bone, especially for being used as the basis for generating bioabsorbable 3D printed scaffolds of personalized treatment against periodontitis, is discussed.

Laser applications in smear layer removal from posterior root canals: A comparative study.

Aim: The aim of the study is to evaluate erbium laser efficiency in removing smear layer from mesial roots of mandibular first molars at different laser settings. Subjects and Methods: One hundred (100) mandibular first molars were selected. Ninety six (96) mesial roots were assigned to two experimental groups according to the laser wavelength applied: I. Er, Cr: YSGG and II. erbium-doped yttrium aluminum garnet laser system. Four samples were used as control group. Samples of each group were distributed into two subgroups (A and B), following specific irrigation protocol. Each subgroup was divided into four subcategories according to the applied power laser. Each subcategory consisted of six samples. Teeth were observed under scanning electron microscope. Statistical Analysis: Results were statistically analyzed with Kruskal-Wallis and Mann-Whitney test (SPSS statistics software). Results: No statistically significant difference was observed between experimental groups I and ΙΙ. However, statistically significant difference was found among subgroups IA and ΙB and ΙIA and ΙΙΒ. In every root third, groups IIA and ΙΙB had better outcomes but it was not statistically significant. There was no statistically significant difference among subcategories of Group I (ΙΑ1-4 and ΙΒ1-4) and Group ΙΙ (ΙΙΑ1-4 and ΙΙΒ1-4). Conclusion: Erbium laser with tested parameters did not completely remove the smear layer from the root canals. Chelating factors can contribute in the laser mechanism of smear layer removal from apical part of narrow and curved root canals.

The Value of Three-Dimensional Modeling on Repositioning and Soft Tissue Filling in Microsurgical Reconstruction of Secondary Mandibular Defects: A Retrospective Study.

Purpose Secondary mandibular defect reconstruction is a challenging operation. It is performed rather rarely, as in most of the cases a primary reconstruction is preferable. Restoration of function and symmetry, in secondary reconstruction of mandibular defects, requires accurate repositioning of segments and appropriate soft tissue filling. The purpose of this study is to estimate the value of three-dimensional (3D) digital modeling to meet the above requirements, in secondary microsurgical reconstruction of mandibular defects. Methods Five cases of mandibular defects, with various degrees of asymmetry and dysfunction, were restored secondarily, with fibula flaps, after virtual reconstruction on a 3D model derived from their computed tomography, with the utilization of CAD-CAM software. Software reproduced symmetrical 3D models by mirroring the healthy side. Occlusion was restored by fine adjustments on 3D models and finally a reconstruction plate was pre-bent on them, prior to its sterilization for use in surgery. Three out of the five cases received an osteo-cutaneous flap, while in the other two patients, an osseous flap was used. Lower face symmetry, mouth opening, and main patient's complaints were evaluated pre- and postoperatively to assess the value of the 3D modeling. Results All flaps survived. Hematoma occurred in two patients and was resolved after evacuation. In two patients, a fistula observed, was attributed to screw loosening, and treated after a surgical debridement and screw replacement. Intraoral exposure in the posterior part of the fibula flap was recorded in one patient, possibly from wound dehiscence due to tension of the intraoral tissue, and successfully covered with an ipsilateral nasolabial flap. The resulting symmetry and function were satisfactory in all the patients. Conclusion Secondary mandibular defects are often related with cosmetic disfigurement, misalignment of mandibular segments, and mandibular malfunction. For the correction of mandibular continuity, symmetry, and restoration of function, preoperative 3D modeling may be an important tool, according to our results.