Molar Teeth Research Articles

ETIOPATHOGENIC ASPECTS OF ODONTOGENIC MAXILLARY SINUSITIS OF PERIAPICAL ORIGIN

Anatomically, the roots of the upper premolar and molar teeth are near the maxillary sinuses. Thus, periapical inflammation of the elements close to the sinuses enables the formation of odontogenic sinusitis. This study aimed to analyze the available literature on the etiopathogenic aspects of odontogenic maxillary sinusitis of periapical origin. A literature review was conducted in the following databases: SciELO, MEDLINE/Pubmed, and LILACS, using the keywords "Maxillary Sinusitis", "Dentistry", "Tooth" and "Infection". Articles written in English, Spanish, and Portuguese were included; those that fit the focus of the paper and those that were most relevant in terms of outlining the desired information. Papers reporting odontogenic sinusitis arising from an operative process were excluded. Odontogenic maxillary sinusitis (OMS) occurs due to sinus infection caused by inflammation of one or more dental elements near this cavity. Despite presenting specific features, sinusitis of odontogenic and non-odontogenic origin are quite similar, making the differential diagnosis difficult. Cone-Beam Computed Tomography (CBCT) is considered the reference standard for diagnosis, and the best treatment is to eliminate the causal factor. It was also found that apical periodontitis is the main non-iatrogenic cause and premolars and molars are the most affected teeth due to their anatomical location near the maxillary sinuses. The anatomical location of the maxillary sinus and the roots of the molars and premolars will allow, through the proximity between them, the OMS. In cases where periodontitis has proven to be the most frequent non-iatrogenic cause of this condition, also due to a great symptomatological similarity with non-odontogenic sinusitis, complementary examinations such as CBCT are necessary. Moreover, the treatment can be performed in a case-specific manner, through accurate diagnosis and etiopathogenesis.

C-Shaped Canal Prevalence and Morphology in Maxillary Molar Teeth: A Cone Beam Computed Tomography Evaluation

C-Shaped Canal Prevalence and Morphology in Maxillary Molar Teeth: A Cone Beam Computed Tomography Evaluation

Preparation and characterization of bovine dental pulp-derived extracellular matrix hydrogel for regenerative endodontic applications: an in vitro study

BackgroundThe use of biological scaffolds in regenerative endodontics has gained much attention in recent years. The search for a new biomimetic scaffold that contains tissue-specific cell homing factors could lead to more predictable tissue regeneration. The aim of this study was to prepare and characterize decellularized bovine dental pulp-derived extracellular matrix (P-ECM) hydrogels for regenerative endodontic applications.MethodsFreshly extracted bovine molar teeth were collected. Bovine dental pulp tissues were harvested, and stored at -40º C. For decellularization, a 5-day protocol was implemented incorporating trypsin/EDTA, deionized water and DNase treatment. Decellularization was evaluated by DNA quantification and histological examination to assess collagen and glycosaminoglycans (GAGs) content. This was followed by the preparation of P-ECM hydrogel alone or combined with hyaluronic acid gel (P-ECM + HA). The fabricated scaffolds were then characterized using protein quantification, hydrogel topology and porosity, biodegradability, and growth factor content using Enzyme-linked immunosorbent assay (ELISA): transforming growth factor beta-1(TGF-β1), basic fibroblast growth factor (bFGF), bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF).ResultsDecellularization was histologically confirmed, and DNA content was below (50 ng/mg tissue). P-ECM hydrogel was prepared with a final ECM concentration of 3.00 mg/ml while P-ECM + HA hydrogel was prepared with a final ECM concentration of 1.5 mg/ml. Total protein content in P-ECM hydrogel was found to be (439.0 ± 123.4 µg/µl). P-ECM + HA showed sustained protein release while the P-ECM group showed gradual decreasing release. Degradation was higher in P-ECM + HA which had a significantly larger fiber diameter, while P-ECM had a larger pore area percentage. ELISA confirmed the retention and release of growth factors where P-ECM hydrogel had higher BMP-2 release, while P-ECM + HA had higher release of TGF-β1, bFGF, and VEGF.ConclusionsBoth P-ECM and P-ECM + HA retained their bioactive properties demonstrating a potential role as functionalized scaffolds for regenerative endodontic procedures.

Bovine pulp extracellular matrix hydrogel for regenerative endodontic applications: in vitro characterization and in vivo analysis in a necrotic tooth model

BackgroundRegenerative endodontic procedures (REPs) offer the promise of restoring vitality and function to a previously necrotic and infected tooth. However, the nature of regenerated tissues following REPs remains unpredictable and uncontrollable. Decellularized extracellular matrix scaffolds have gained recent attention as scaffolds for regenerative endodontics.ObjectivesPreparation and characterization of a bovine dental pulp-derived extracellular matrix (P-ECM) hydrogel for regenerative endodontic applications. Biocompatibility and regenerative capacity of the prepared scaffold were evaluated in vivo in a canine animal model.MethodsFifteen freshly extracted bovine molar teeth were used to prepare P-ECM hydrogels following approval of the institutional review board of the faculty of dentistry, Alexandria University. Decellularization and lyophilization of the extracted pulp tissues, DNA quantification and histological examination of decellularized P-ECM were done. P-ECM hydrogel was prepared by digestion of decellularized pulps. Prepared scaffolds were evaluated for protein content and release as well as release of VEGF, bFGF, TGF-β1 and BMP2 using ELISA. Rabbit dental pulp stem cells’ (rDPSCs) viability in response to P-ECM hydrogels was performed. Finally, proof-of-concept of the regenerative capacity of P-ECM scaffolds was assessed in an infected mature canine tooth model following REPs versus blood clot (BC), injectable platelet-rich fibrin (i-PRF) or hyaluronic acid (HA). Statistical analysis was done using independent t test, the Friedman test and chi-square tests (p value ≤ 0.05).ResultsDNA was found to be below the cut-off point (50 ng/mg tissue). Histological evaluation revealed absence of nuclei, retention of glycosaminoglycans (GAGs) and collagen content, respectively. P-ECM hydrogel had a total protein content of (493.12 µg/µl) and protein release was detected up to 14 days. P-ECM hydrogel also retained VEGF, bFGF, TGF-β1 and BMP2. P-ECM hydrogel maintained the viability of rDPSCs as compared to cells cultured under control conditions. P-ECM hydrogel triggered more organized tissues compared to BC, i-PRF and HA when used in REPs for necrotic mature teeth in dogs. Periapical inflammation was significantly less in HA and P-ECM groups compared to blood-derived scaffolds.ConclusionBovine dental pulp-derived extracellular matrix (P-ECM) hydrogel scaffold retained its bioactive properties and demonstrated a promising potential in regenerative endodontic procedures compared to conventional blood-derived scaffolds.

Evaluation of hard tissue characteristics and calcifications in pulp tissue of hypomineralized permanent molars using micro-computed tomography

ObjectivesTo determine and compare pulp volume, dentin mineral density, presence of microcracks, pulp stones, and accessory canals, as well as their localizations in root regions for hypomineralized and healthy teeth. DesignThis study included 60 extracted permanent molar teeth, categorized into hypomineralized and healthy groups (n = 30 each). The hypomineralized group comprised molar teeth with limited white, yellow, or brown opacities, post-eruptive breakdown, or extensive restoration or crown damage. The healthy group included caries-free molar teeth without these characteristics. Using 3D micro-computed tomography images pulp volume, dentin mineral density, and the presence and locations of microcracks, pulp stones, and accessory canals were determined for each group. Statistical analyses were conducted using Independent T-test and Chi-square test, with significance set at p < 0.05. ResultsThere was no statistically significant difference between the groups regarding pulp volume and microcracks (p ≥ 0.05). The number of accessory canals was significantly greater in the cervical (p = 0.011; p < 0.05) and middle (p = 0.010; p < 0.05) regions of the hypomineralized teeth than healthy teeth. Dentin mineral density was statistically higher in the apical, middle, and cervical root regions (p < 0.001; p < 0.05); however, the number of pulp stones was found to be greater in the cervical regions of healthy teeth compared with those with hypomineralization (p = 0.026; p < 0.05). ConclusionThere were lower dentin mineral density measurements, a decreased number of pulp stones in the cervical region, and a greater number of accessory canals in the middle and cervical regions of hypomineralized teeth compared with healthy teeth.

Association between molar incisor hypomineralisation and tooth agenesis: a cross-sectional study in Brazilian children and adolescents.

The aim of the present was to assess the association between MIH and tooth agenesis (TA) in orthodontic patients from the Federal University of Rio Grande do Norte, Natal, Brazil. A cross-sectional study was performed to evaluate the presence of MIH and TA in a sample of 371 pretreatment orthodontic records from patients aged 9-18years. Statistical analyses were performed using the Chi-square and Fisher's exact tests, and logistic regressions. There was a statistically significant association between the prevalence of tooth agenesis and MIH. A higher percentage of third molar agenesis, maxillary premolar agenesis, and mandibular second premolar agenesis was observed among children with MIH-affected teeth. Patients with MIH had a 2.43 times greater chance of third molar agenesis, and a 5.88 times higher likelihood of mandibular premolar agenesis. There is a weak association between MIH and TA. Furthermore, the presence of hypomineralised molars increases the risk of tooth agenesis.

Radiographic association of chronological age based on the root pulp and periodontal ligament visibility in lower second molar teeth in a subset of the Pakistani population

Objective: To find radiographic association of the root pulp visibility and periodontal ligament visibility stages of lower second molar teeth with chronological age. Method: The prospective, analytical, cross-sectional study was conducted after approval from the ethics review committee of Ziauddin University, Karachi, and comprised digital orthopantomograms from 2020 to 2022. The orthopantomograms related to lower second molar teeth from the left side of the mandible of individuals of either gender aged 18-40 years. The orthopantomograms were subjected to stage classification to assess the radiographic root pulp visibility and periodontal ligament visibility of the lower second molar teeth. Data was analysed using SPSS 25. Results: Of the 260 orthopantomograms, 140(53.8%) belonged to female subjects and 120(46.2%) to male. The overall median age of the subjects was 24 years (interquartile range: 7 years). There were 164(63.1%) subjects aged 18-25 years, 70(26.9%) aged 26-33 years, and 26(10%) aged 34-40 years. A positive correlation was noted between age and stages of radiographic root pulp visibility and periodontal ligament visibility (P&lt;0.05). The individuals found at stages 0 and 1 for root pulp visibility were aged at least 18 years, and for stage 2, the corresponding value was 21 years. For periodontal ligament visibility, the minimum age for stage 0 was 18 years, while for stages 1 and 2, the corresponding values were 21 and 25 years. Conclusion: Lower age was found to be associated more with stage 0 of root pulp visibility and periodontal ligament visibility. Key Words: Panoramic radiography, Periodontal ligament, orthopantomography, Dental pulp.

Full pulpotomy versus root canal therapy in mature teeth with irreversible pulpitis: a randomized controlled trial

BackgroundVital pulp therapy (VPT) is recommended as an alternative treatment to root canal therapy (RCT) for management of teeth with carious pulp exposure. This randomized clinical trial aimed to compare the outcomes and postoperative pain, and to evaluate the time and cost after full pulpotomy (FP) and RCT in mature molar teeth with irreversible pulpitis (IP).MethodsA total of 160 mature molar teeth with IP were randomly divided into two treatment groups. The FP group (test group) was treated with FP using iRoot BP Plus by an endodontist, the RCT group (control group) was treated with RCT using iRoot SP as sealer by the same endodontist. Pain was recorded preoperatively and daily until day 7 postoperatively. The treatment time and cost were recorded. Clinical and radiographic assessments were collected, and pulp sensibility tests were done by electric pulp test (EPT) at 3-, 6-, 12- month postoperatively. Data were analyzed through chi-square test, Mann-Whitney U test, Fisher exact and independent t test.ResultsFP and RCT had comparable success rates (Clinical, 97.3% vs. 98.6%; radiographic, 93.3% vs. 94.6%) (P > 0.05). Pain levels decreased over time from day 1 to day 7 postoperative in both groups, and the FP group had larger reductions in pain intensity than RCT at day 1 (P < 0.05). In the FP group, there were 5, 3 and 3 unresponsive teeth with EPT at 3-, 6- and 12- month follow-ups, respectively. The treatment time and cost in the FP group were significantly lower than in the RCT group (P < 0.05).ConclusionsFP could be an appropriate alternative treatment for management of mature teeth with IP in short follow-up.Trial registrationThe trial was registered in Chinese Clinical Trial Registry (ChiCTR2200063380 at 05/09/2022).

Efficacy of proinflamatory cytokines in the clinical and radiograpic outcomes of different primary molar pulpotomy agents: a comperative randomised study featuring a novel biomarker for pulpal diagnosis

BackgroundWhile the effect of biomaterials covering the pulp tissue is considered in the success of pulpotomy treatment, the level of pulpal inflammation is still very important for treatment success. The aim of this study was to compare IL-6 and IL-8 levels, known as good indicators of pulpal inflammation, with a new biomarker, presepsin, and to evaluate the impact of biomarker levels along with the pulp capping agents used in the treatment on the one-year success of pulpotomy treatment.MethodsThe study included 120 primary second molar teeth with pulpotomy indications from 75 children. To determine the pulpal inflammation status, pulpal bleeding samples were taken during treatment, and the levels of IL-6, IL-8, and presepsin were measured. During the pulpotomy treatment, MTA, NeoMTA™, and Biodentine™, and ZOE were randomly applied to groups of thirty teeth each. Patients were monitored for a period of 12 months post-treatment.ResultsIL-8, IL-6, and presepsin levels were significantly higher in teeth with pathology (p < 0.001). Biomarker levels were found to be higher in the NeoMTA and Biodentine groups, but this did not result in a statistically significant difference. (p > 0.05) Following pulpotomy treatment, the most successful material groups in order were MTA, ZOE, NeoMTA™, and Biodentine™.ConclusionPresepsin may be a usable indicator in predicting the level of inflammation. At the end of the one-year follow-up of pulpotomy treatment, more pathology was observed in the NeoMTA and Biodentine groups, where biomarker levels were higher, while no pathology was found in the MTA group, where biomarker levels were lower.Trial registrationNCT06398327/ 20,240,503.

A conservative treatment of an involved molar tooth associated with dentigerous cyst: a case report and literature review

BackgroundDentigerous cysts (DCs) are among the most frequently odontogenic cysts in young and middle-aged individuals. Marsupialization and enucleation are the main treatment options in clinical practice. However, there are few reports on preserving molars severely involved by the cyst.Case presentationA 35-year-old male patient with a large odontogenic cyst that was successfully treated using a multidisciplinary approach. The patient’s chief complaint was discomfort during mastication in the lower left molar region for a month. Clinical examination revealed that teeth 36 and 37 were intact without pain upon percussion, while tooth 38 was unerupted. The radiology examination illustrated a typical well-defined oval radiolucent lesion surrounding the crown of unerupted tooth 38, extending to the distal root of tooth 37. The treatment was divided into two parts: removal of the cyst and the impacted third molar, followed by filling with collagen bone particles; and preserving the tooth 37 via hemisection, root canal treatment and crown restoration. Pathological examination indicated a dentigerous cyst. After 18 months of treatment, the bone defect completely recovered and tooth 37 functioned well following the hemisection.ConclusionsHemisection effectively preserves the cyst-associated molars and maintains oral function. This article underscores the significance of collaboration among various departments in the treatment of odontogenic cysts, ultimately aiming to achieve minimally invasive and functional surgery.

Evaluation of Wear on Primary Tooth Enamel and Fracture Resistance of Esthetic Pediatric Crowns Manufactured from Different Materials

Background and Objectives: Advances in dental materials and CAD-CAM technology have expanded crown options in primary teeth due to their improved appearance and mechanical properties. Thus, this study aimed to assess the enamel wear and fracture resistance of prefabricated, milled, and 3D-printed esthetic pediatric crowns. Materials and Methods: The study involved 60 extracted maxillary second primary molars and 60 3D-printed resin dies, divided into six groups based on different crown materials (n = 10): prefabricated zirconia, prefabricated composite, milled composite, milled resin matrix ceramic, milled PEEK, and 3D-printed resin. Prefabricated crowns were selected after the preparation of the typodont mandibular second primary molar tooth, while milled and 3D-printed crowns were custom produced. The specimens underwent mechanical loading of 50 N at 1.6 Hz for 250,000 cycles with simultaneous thermal cycling. The 3D and 2D wear amounts were evaluated by scanning the specimens before and after aging. Then, the fracture resistance and failure types of the restorations were recorded. Results: The results showed that the milled PEEK group had superior fracture resistance compared to the other groups, while prefabricated zirconia crown group had the lowest value. Milled resin matrix ceramic crown group displayed the lowest 3D wear volume, while 3D-printed crown group showed the highest 2D wear. Conclusions: The restorative material type did not have a significant effect on the wear of primary tooth enamel. The fracture resistance of the tested materials differed according to the material type. Although the milled PEEK group showed the highest fracture resistance, all tested materials can withstand chewing forces in children.

Integration Patterns of Molar Tooth Rows in the Extant Voles (Mammalia: Arvicolnae): Geometric Morphometric Analysis at a Macrolevel

Integration Patterns of Molar Tooth Rows in the Extant Voles (Mammalia: Arvicolnae): Geometric Morphometric Analysis at a Macrolevel

A Cross-Sectional Study On Determination Of Age From Third Molar Tooth Eruption In The Population Of Telangana.

Age has got significant role in Forensic medicine. It helps in identification and correlates various civil and criminal related issues. A cross sectional study on age determination from eruption of third molar tooth was conducted at Malla Reddy Institute of Medical sciences Hyderabad Telangana for a period of one year in the age group between 18 years to 25 years. A total of 160 medical students were participated in which 80 males and 80 females were participated in the study. Each individual was examined for physical dental examination in each quadrant of the jaw, mere appearance of crown of the third molar tooth was considered as erupted. A space between the second molar tooth and the ramus of the mandible without any evidence of the crown of the 3rd molar tooth was considered as not erupted. Statistical results reveal 54.2% of the study population third molar teeth eruption was observed first in the lower left quadrant. 96.2% in male and 98.4% in female individuals third molar was erupted at 22 years of age and at 23 years third molar was completely erupted in all the quadrants of the jaw in both male and female population.

A randomized controlled clinical trial of the performance of three bioactive endodontic cements in primary molar teeth diagnosed with reversible pulpitis: 1-year follow-up study

ObjectivesThe objective of this clinical trial was to evaluate and compare the clinical and radiographic successes of three bioactive endodontic cements (BEC) including novel portland cement-based material releasing fluoride, resin-modified silicate glass cement, and pure tricalcium silicate-based cement—in the treatment of primary molars diagnosed with reversible pulpitis via indirect pulp capping. MethodsEighty-six (86) participants with previously untreated first and second primary molars were included in this study. The teeth were randomly allocated into three groups: pure tricalcium silicate-based cement, resin-modified silicate glass cement, and novel portland cement-based material releasing fluoride. Cavities were capped with the assigned cement after caries excavation using standard protocols. The teeth that underwent treatment were restored using glass ionomer cement and composite resin. Clinical and radiographic evaluations were performed at 1, 6, and 12 months. The data were analyzed using Pearson chi-square, Kruskal–Wallis H and Z test (P = 0.05). ResultsThe success rate was 88 % (n = 25) in the pure tricalcium silicate-based cement group, 88.5 % (n = 26) in the resin-modified silicate glass cement group, and 100 % (n = 25) in the novel portland cement-based material releasing fluoride group. The differences at the 1st, 6th, and 12th month follow-up visits were not statistically significant among the groups (P > 0.05). No difference was found between the integrity of the resin composite restorations overlying pure tricalcium silicate-based cement, resin-modified silicate glass cement, and novel portland cement-based material releasing fluoride according to the USPHS criteria. ConclusionsNovel portland cement-based material releasing fluoride can be considered an alternative for preserving the tooth, as it showed a high success rate in treating primary molars diagnosed with reversible pulpitis via indirect pulp capping. Clinical significanceNovel Portland cement-based material releasing fluoride could be beneficial in the treatment of primary molars diagnosed with reversible pulpitis via indirect pulp capping.

Evaluation of fractal analysis and radiomorphometric measurements of mandibular bone structure in bruxism and non-bruxism paediatric patients.

The goal of this examination was to compare the impact of probable sleep/awake bruxism on the mandibular trabecular bone structure by fractal analysis (FA) with digital panoramic radiograph (DPR) and radiomorphometric measurements in paediatric patients with bruxism. The examination included 130 participants with 63 patients with probable sleep/awake bruxism and 67 control groups. Bilateral regions of interest (ROI) in three regions were examined as ROI1: mandibular ramus, ROI2: mandibular angulus, ROI3: anterior to the molar teeth. Radiomorphometric measurements were taken of the mandibular cortical width (MCW), panoramic mandibular index (PMI), and mandibular cortical index (MCI). p < 0.05 was approved for statistical significance. The ROI-1, ROI-2, and ROI-3 values were defined to be statistically significantly high in the bruxism group (p < 0.05). No significant difference was found between the groups in the other values (p > 0.05). There was no difference in the age and gender for any of the parameters (p > 0.05). In children and adolescents, the mandibular trabecular bone can be affected by bruxism. FA can be used as an auxiliary method for finding the mandibular trabecular differences of patients with bruxism in paediatric dentistry just as it can for adults.

Flexural Strength of Nanohybrid Composite Resin: An in-vitro Study

In the present study, the Flexural strength of nanohybrid composite was compared with conventional microfilled composite resin in vitro. Thirty nanohyrid and 30 conventional microfilled composite resins were subjected to Flexural strength measurement as follows; a teflon mold (4 mm in diameter and 6 mm in depth) was filled with materials, light cured through the glass slides for 40 sec top and bottom surfaces. Then the specimens were taken out from the mold, again light curing for 40 sec, stored in dry condition and placed into a Flexural strength tester and loaded until fracture of the sample. Student t-test was performed to assess the differences between two groups and a value of p &gt;0.05 was considered as statistically significance. The results showed that the means ± SD Flexural strength of nanobybrid and conventional microfilled composite resin were 118.70 ± 3.90 Mpa and 77.43 ± 2.65 Mpa, respectively and the differences were statistically significant. It can be concluded that nanohybrid is superior to conventional microfilled composite resin in respect to Flexural strenth in class II restorations of permanent molar teeth.

The Relationship between Impacted Mandibular Third Molar and Mandibular Canal on Orthopantomogram – A Retrospective Study

Background: Surgical removal of the impacted lower third molar teeth require thorough investigations and assessment, one of these very important investigations is orthopantomogram (OPG) which is the primary assessment method, to determine the relationship between impacted mandibular third molar and mandibular canal. The study aims to determine the relationship between impacted mandibular third molar and mandibular canal on orthopantomogram. Materials and methods: A retrospective of 300 OPGs out of 947 OPG were selected using simple random sampling method. Rood’s criteria was used in assessing the relationship between the apex of the roots and upper border of the inferior alveolar canal. Statistical analysis was performed to assess the relationship between the canal and the impacted lower third molar in relation to the age ,gender and type of impaction.Results: From 300 OPG, 473 impacted teeth were identified, the relation showed, the highest percentage was superimposed with 47.3%, followed by close contact (35.7%), and only 21.7% of the impacted teeth examined has distance between the roots and the upper border of mandibular canal.Conclussion:Mesioangular impaction has higher percentage of superimposition with the mandibular canal with the higher percentage of female58% to male42% ratio.

The Impact of Muscle Energy Techniques on the Temporomandibular Motions Following Extraction Surgery of the Third Molar Tooth: A Randomised Clinical Trial.

Trismus and subsequent restricted range of motion in the temporomandibular joint may impede vital activities of daily living. The primary purpose of the current study was to explore the impact of muscle energy techniques on the range of temporomandibular motions in individuals with trismus and restricted range of the temporomandibular motions after third molar extraction surgery. Eligible volunteers were randomly assigned to either the intervention or control group. Participants in the intervention group received muscle energy techniques over seven consecutive postoperative days, while those in the control group did not receive any intervention. Both groups adhered to the recommended postoperative healthcare protocol provided by a single dentist. The range of cardinal and linear intra-articular motions of the temporomandibular joint was assessed on the first, second and seventh postoperative days in each group using a vernier calliper and an ultrasound machine, respectively. The range of linear intra-articular motion (p-value < 0.001) and cardinal motion (p-value < 0.032) of the TMJ significantly increased within groups after the first postoperative week. The range of temporomandibular motions, except for the forward displacement of the mandibular condyle (p-value = 0.193), and the range of mandibular retrusion (p-value = 0.339) exhibited a significant difference between groups (p-value < 0.017) after the first postoperative week. The current study revealed, for the first time, that muscle energy techniques increase the range of cardinal and linear intra-articular motions in individuals with trismus and restricted range of the temporomandibular motions following third molar extraction surgery. Clinical Trials: IRCT20211016052783N1.

Development of a Preclinical Double Model of MandibularIrradiated Bone and Osteoradionecrosis in NewZealand Rabbits.

Radiotherapy (RT) plays a crucial role in head and neck (HN) cancer treatment. Nevertheless, it can lead to serious and challenging adverse events such as osteoradionecrosis (ORN). A preclinical rabbit model of irradiated bone and ORN is herein proposed, with the aim to develop a viable model to be exploited for investigating new therapeutic approaches. Nine New Zealand white rabbits were irradiated using a single beam positioned to the left of the mandible and directed perpendicular to the left mandible. A 10 × 10 mm2 region of interest (ROI) located below the first molar tooth on the left side was identified and irradiated with 7 Gy each fraction, once every 2 days, for five fractions. Dose distributions demonstrated that the corresponding ROI on the contralateral (right) mandibular side received approximately 5 Gy each fraction, thus bilateral irradiation of the mandible was achieved. ROIs were categorized as ROIH on the left side receiving the high dose and ROIL on the right side receiving the low dose. Rabbits were followed up clinically and imaged monthly. After 4 months, the irradiated bone was excised, and histological examination of ROIs was performed. Radiological signs suggestive for ORN were detected in the entire population (100%) 16 weeks after irradiation on ROIH, which consisted of cortical erosion and loss of trabeculae. ROIL did not show any radiological evidence of bone damage. Histologically, both sides showed comparable signs of injury, with marked reduction in osteocyte count and increase in empty lacunae count. A preclinical double model was successfully developed. The side receiving the higher dose showed radiological and histological signs of bone damage, resulting in an ORN model. Whereas the contralateral side, receiving the lower dose, presented with histological damage only and a normal radiological appearance. This work describes the creation of a double model, an ORN and irradiated bone model, for further study using this animal species.

Magnetic Resonance Images for the Prediction of Chronological Age Using Maxillary Third Molar Teeth: An Observational Study.

Dental age estimation using third molars is a reliable method for estimating the age of individuals. Recently, magnetic resonance imaging (MRI) of the head and neck has been found to be applicable for age estimation of third molar teeth. In the present study, we aimed to apply the Modified Demirjian method of age estimation to magnetic resonance (MR) image sections for dental age estimation by determining the mineralization patterns of the maxillary third molars. MRI scans of the patients were performed using SIGNA™ 3.0Tesla MRI GE Healthcare (Chicago, USA) with a moving, multifunctional coil. Two expert radiologists with more than three years of experience independently analyzed the image sections using the open-source Digital Imaging and Communications in Medicine (DICOM) viewer software. The age and sex of the patients whose images were included in the study were recorded using a specially designed proforma. The stage of development of the maxillary third molars was determined using the modified Demirjian method. Inter observer agreement was calculated using the intra class correlation coefficient. Simple linear regression analysis was used to predict the actual age at the third molar development stage. There was excellent agreement between observers (ICC =0.99 (95% CI = 0.98-0.99)). There was also a significant association between the maxillary third molar tooth development stage and chronological age of the individual (P=0.001; B=1.54; 95% CI = 0.71-2.37). The findings from the present study establish that the Modified Demirjian method can also be reliably applied for dental age assessment in MR sections.