Roots Of Molars Research Articles

Spatial Position and Anatomical Characteristics Associated with Impacted Third Molars Using a Map-Reading Strategy on Cone-Beam Computed Tomography Scans: A Retrospective Analysis

(1) Background: This study assessed the spatial position and anatomical features associated with impacted third molars through a map-reading strategy employing cone-beam computed tomography (CBCT). (2) Methods: The positioning of impacted third molars on CBCT was assessed using Winter’s and Pell and Gregory’s classifications. External root resorption in mandibular second molars was categorized according to Herman’s classification. Additionally, the relationship between the mandibular third molar root apex and the mandibular canal was examined. Comparative statistical analysis was conducted using Fisher’s exact test, with a significance level considered as 5%. (3) Results: The results indicated that, based on Winter’s classification, 48.06 % of impacted teeth were positioned mesioangularly. Employing Pell and Gregory’s classification, 43.22% of the impacted molars fell into positions B and C, with 54.2% classified as Class II. A notable 69.7% of teeth exhibited no contact between the root apex and the mandibular canal, and external root resorption in the distal aspect of the second molar was absent in 88.7% of cases. (4) Conclusions: Utilizing the map-reading strategy with CBCT scans to assess the anatomical positions and characteristics of impacted third molars enhances professional confidence and sets a standard for quality and safety in the surgical procedure for patients.

Endodontic management of type I maxillary first molar with two palatal roots using cone-beam computed tomography

Background: Understanding the anatomical variations in the root canal system is vital for the successful outcome of endodontic treatment. Anatomical variation with respect to palatal roots is rare compared with other roots of maxillary molars. Purpose: This case report describes a rare case of cone-beam computed tomography (CBCT)-guided endodontic treatment of a maxillary first molar with two palatal roots. Case: A 35-year-old Saudi woman complained of continuous pain in the right maxillary first molar. Past dental history revealed root canal treatment of the same tooth four weeks prior. Master cone radiographs recovered from her general dentist revealed a missing second palatal canal. Case Management: A CBCT image was taken to confirm if there were any aberrations in root canal morphology. Clinical exploration presented four distinct orifices: two palatal and two buccal. All the root canals were prepared and irrigated with 2.5% NaOCl and normal saline during instrumentation. All the canals were obturated with gutta-percha and AH 26 sealer using the continuous wave obturation technique. Conclusion: Clinical exploration of the pulpal floor, along with multiple angled radiographs, is needed to confirm any anatomic aberration.

Fibroblast growth factor signalling regulates the development of tooth root.

Fibroblast growth factor (FGF) signalling plays a crucial role in the morphogenesis of multiple tissues including teeth. While the role of the signal has been studied in tooth crown development, little is known about root development. Of several FGF ligands involved in hard tissue formation, we suggest that FGF18 regulates the development of murine tooth roots. We implanted FGF18-soaked heparin beads into the lower first molar tooth buds at postnatal day 6 (P6), followed by transplantation under the kidney capsule. After 3 weeks, FGF18 significantly facilitated root elongation and periodontal tissue formation compared to the control. Insitu hybridisation showed that Fgf18 transcripts were initially localised in the dental pulp along Hertwig's epithelial root sheath at P6 and P10 and subsequently in the dental follicle cells at P14. Fgf receptors were expressed in various dental tissues during these stages. Invitro analysis using the dental pulp stem cells revealed that FGF18 inhibited cell proliferation and decreased expression levels of osteogenic markers, Runx2, Alpl and Sp7. Consistently, after 1 week of kidney capsule transplantation, FGF18 application did not induce the expression of Sp7 and Bsp, but upregulated Periostin in the apical region of dental mesenchyme in the grafted molar. These findings suggest that FGF18 facilitates molar root development by regulating the calcification of periodontal tissues.

Apical enlargement favors endodontic irrigation – an in vivo study

Objective: This study evaluated the irrigation penetration during root canal instrumentation and the clinical step in which the irrigation solution can be detected in the apical region.
 Materials and Methods:
 Twenty necrotic molars were divided according to the irrigation protocol, saline solution with manual active pressure, and 2.5% sodium hypochlorite with dripping delivery. Solution penetration assessment used a radiopaque component added to each irrigant solely before a periapical radiograph. Instrumentation sequence was: #10, and #15 K-files (step 1), cervical flaring using WaveOne Small (step 2), WaveOne Small at working length (step 3), Hero-642 #35/.02 (step 4), and Hero-642 #40/.02 (step 5). The step each contrasted-irrigant reached the 2-mm-apical region was registered. Shapiro-Wilk and Fisher's exact tests were used for comparisons.
 Results: In step 3, both contrasted-irrigants started to be detected in the apical region, and after step 5, contrasted-irrigants penetrated in 100% of the cases, without significant difference.
 Conclusion: Considering distal molar roots, the apical enlargement up to an instrument #40.02 favors the irrigation to reach the 2-mm apical region.

The Patterns of Impacted Third Molars and Their Associated Pathologies: A Retrospective Observational Study of 704 Patients.

Background: The study aims to investigate parameters in patients attending Fujairah Dental Center, including assessing the prevalence of impacted teeth, determining the frequency of associated pathological conditions, and evaluating the patterns and angulations of impacted third molars. Methods: It is a retrospective descriptive study of the panoramic radiographs of patients who attended Fujairah Dental Center for dental care between January 2011 and December 2017. The minimum age for inclusion was 17 years. Clinical records were used to obtain the demographic details of patients, such as age, gender, nationality, medical history, and smoking history. Seven hundred and four panoramic radiographs and clinical records of patients were analyzed. The age range was between 17 and 112 years old, with a mean age of 34 years (S.D 13.5). Results: Of the 704 panoramic radiographs evaluated, 236 (33.6%) X-rays showed teeth impaction with a total of 562 impacted teeth in the upper and lower jaws. Five hundred and twenty-five (93.4%) were impacted third molars, and 37 (6.5%) teeth were other kinds of impacted teeth. Females showed a higher frequency of impacted teeth (62.6%) compared to males (37.4%). The highest prevalence of impacted teeth was found in the 17-25 year age group (61%), and the prevalence declined with advancing age. Impacted third molars were more likely to occur in the mandible (57.3%) than in the maxilla (42.7%). Most of the impacted third molars were in the mesioangular position, followed by the vertical position. The evaluation of the depth of impacted third molars demonstrated that level C impaction was the most frequently seen, followed by level B impaction. Impacted third-molar teeth often presented with two roots (60.7%), followed by a single root (31.3%). An evaluation of the relationship between lower third molars and the inferior dental canal (IDC) revealed that the most frequently observed relation was interrupted (61.5%), followed by a distant relation to the ID canal, and 13% were superimposed. The most common morphological pattern of roots of the impacted third molars was either straight-type or curved and dilacerated roots (5.7%). Additionally, the most noticed pathological conditions associated with impacted teeth were carious second molars adjacent to impacted third molars (42%), which was more likely to be seen in the 17-25-year age group, with females having a higher prevalence than males.

Distolingual root prevalence in mandibular first molar and complex root canal morphology in incisors: a CBCT analysis in Indian population

Cone-beam computed tomography was used to understand the possible correlation between the prevalence of distolingual root (DLR) in permanent mandibular first molars (MFMs) and the associated complicated mandibular incisor’s root canal morphology (MIs) in an Indian population. A total of 400 scans were evaluated for MFMs and MIs. The prevalence of DLRs and root canal anatomy of MIs were assessed based on Vertucci’s classification, and then the sample were grouped according to age, sex and side. Statistical analysis was used to evaluate the possible correlation between the presence of DLRs in the first molar and root canal morphology of incisors. Chi square test was used to evaluate the correlation between the root canal configurations of MIs with the existence of DLRs in MFMs. There was no statistically significant difference between sexes or ages for the prevalence of DLRs in the first molars (p > 0.05), which was 6.62%, with the right side having a greater frequency of DLRs (7.8%) than the left (5.5%). Vertucci Type I canal configuration was most common for the mandibular central (66.75%) and lateral incisors (58.62%). Vertucci Type III was the most common complicated canal morphology, followed by Types V, II, and IV for MIs, with no statistically significant difference in the studied sample's age and sex. (p < 0.05). No association was observed between the presence of DLRs in first molars and complicated root canal configurations in MIs. Taken together, the possibility of complicated root canal configuration in MIs was lesser in the presence of DLRs in MFMs among the Indian population.

Micro-CT Assessment of Filling Removal Effectiveness in the Apical Third of Curved Canals with Different Types of Anatomy.

The aim of this study was to assess the effectiveness of filling removal material from the apical third of curved mesial root canals of mandibular molars. Reciprocating instrumentation followed by additional rotary instrumentation with instruments made of alloys with different heat treatments was evaluated. Thirty-six mesial roots of mandibular molars were divided into two groups: Group Class IV consisted of 16 roots with two independent canals, and Group Class II consisted of 20 roots with two canals that merged into one at their apical level. Each of these two groups were further divided into two subgroups, according to the additional rotary instrument used after the reciprocating instrumentation: Group RH and Group RM for Hyflex and Mtwo, respectively. After each procedural step, the roots were scanned by micro-tomography. After each step of filling removal, the Wilcoxon matched pair test and the Mann-Whitney test were used for the evaluation between groups. The significance level adopted was 5%. Significant differences were observed between groups with different Class II and Class IV anatomies, regarding filling removal after Reciproc (P<0.05). After the use of an additional rotary instrumentation, no differences were observed between the two groups (P>0.05). In the apical third of mesial roots of mandibular molars with Class II anatomy, an additional rotary instrumentation was shown to be necessary for improving the removal of filling material after using the single-file reciprocating instrumentation technique.

Prevalence of Isthmi and Root Canal Configurations in Mandibular Permanent Teeth Using Cone-Beam Computed Tomography.

While root canal anatomy in Middle Eastern populations is well-studied, research on isthmi in mandibular permanent teeth from this region is limited. This retrospective study used cone-beam computed tomography (CBCT) to examine isthmi prevalence and location, as well as root canal morphologies (per Vertucci's classification) in mandibular permanent teeth from a subpopulation in Ardabil, Iran. The study is aimed at enhancing our understanding of dental anatomical variations in Middle Eastern populations. A total of 3566 teeth from 384 CBCT scans were evaluated in this retrospective study. Mandibular teeth were evaluated on sagittal, coronal, and axial sections regarding the presence of isthmus and root morphology (Vertucci's classification). CBCT scans of 197 males (51.3%) and 187 females (48.7%) were evaluated, with a mean age of 41.1 ± 11.4 years. Isthmi were most prevalent in molar mesial roots, typically located in the middle third for anterior teeth and first premolars and cervical third for posterior teeth. While gender did not play a significant role, the presence of an isthmus in the mesial root of the left second molars was associated with a younger mean patient age (p < 0.05). Root morphology varied across tooth types. Central and lateral incisors predominantly showed Vertucci's Types I and III. Canines and premolars were mostly Type I, with some variation. Molar mesial roots frequently exhibited Types IV and II, while distal roots were predominantly Type I. Statistically significant differences were found between morphology and gender in the first left premolar (Type I more common in women; Type V in men; p < 0.001) and in the right canine (Type I more prevalent in men; Types III and V more prevalent in women; p < 0.001). The results revealed wide variations in root canal morphology and a relatively high prevalence of isthmi in the study population. Our findings suggest a potential difference in tooth anatomy based on sex and a relationship between age and the presence of isthmi.

Influence of Different Glide Path Techniques on Microcrack Formation after Two Different Root Canal Preparation Treatments: Micro Computed Tomography Analysis.

This study aimed to evaluate the effect of WaveOne Glider (WOGG) with Waveone Gold (WOG) primary reciprocation systems on root dentine microcrack formation and to know the effect of TruNatomy Glider (TRNG) with TruNatomy (TRN) prime rotary systems on root dentine microcrack formation. In this study, 40 extracted mandibular first molar roots were selected and divided randomly into four groups (n=10). Group MWOG: a manual glide path was performed + WOG primary. Group MTRN: manual glide path performed+TRN prime. Additionally, group WOGG: glide path preparation with WOGG+WOG primary. Finally, for group TRNG, the glide path preparation was performed with TRNG+TRN prime. Micro-CT was used for pre and post-instrumentation image analysis. Statistical analysis was performed using the Kruskal- Wallis test (p<0.05) with Two-way ANOVA. The Kruskal-Wallis test showed no significant differences among all groups in all thirds for pre and post-instrumentation regarding the crack formation. The Two-way ANOVA showed no significant difference or interaction between the ways of glide path preparation, whether manual or reciprocal WOGG, or between the rotary TRNG and the motion used in root canal preparation (rotary TRN or reciprocal WOG) regarding the crack formation and propagation. Microcrack formation and propagation occurred independently of using different glide path techniques (manual, rotary, or reciprocal).

Histological and immunohistochemical characteristic of the gingival stroma in the portion of the third molars in children of various age.

Aim: To evaluate the state of the gingival stromal elements in the portion of the third molars requiring extraction of these teeth due to orthodontic indications considering the stage of tooth germ formation. Materials and Methods: The surgery to extract third molars due to orthodontic indications was performed on 95 children aged 11 to 18 years. The three groups of observation were isolated according to clinical-radiological signs: І (n=30) - children aged 11-13 years; ІІ (n=35) - children aged 13-16 years, and ІІІ (n=30) - children aged 16-18 years. During surgery, the samples of gums were taken from the adjacent areas for examination. The samples were fixed, dehydrated, paraffinized for further histological processing. Immunohistochemical methods were used according to the protocols supplied by a producer. In particular, by means of immunohistochemical method, Ki-67, CD-34 antigens and vimentin with primary antibodies against them were determined. The primary antibodies were visualized by the polymeric visualization system with diaminobenzidine giving a brown color to the places of location of the antigens examined. The data obtained were statistically processed. Results: The results of the study showed that specific gravity of the vascular bed in the gingival papillary layer of children was the most variable. It ranges from (12,7±0,09) % at the stage of "D" root formation to (54,8±0,17) % at the "H" stage. Lower concentrations of CD-34 antigens and vimentin are found in the endotheliocytes of children aged 13-16 and 16-18 years, compared to the children aged 11-13 years (p<0,05). No changes were found in the specific volume of the blood vessels, CD-34 antigens and vimentin in the reticular gingival layer of children from the groups of observation. Conclusions: Therefore, the conducted histological and immunohistochemical study of the connective gingival tissues in the portion of the third molars in children enables to draw a conclusion that in the process of formation of the root of this tooth a number of changes occur in the gingival stroma. They include an increase of the blood flow volume in the papillary gingival layer on the background of a decreased concentration of CD-34 genes and vimentin, a longer stage of development of the third molar root. The specific volume of the islets of neoangiogenesis of the papillary gingival layer is the largest in children aged 13-16 years.

Three-dimensional visualization of Hertwig's epithelial root sheath during tooth root development with the miniTESOS tissue clearing method.

Hertwig's epithelial root sheath (HERS) acts as a signaling center that regulates the size, shape, and number of tooth roots. Therefore, understanding the anatomical changes in HERS during development is crucial for investigating its effect on root formation. However, the three-dimensional morphology of HERS and its changes during tooth root development remain largely unknown due to the limitations of traditional histological techniques. We developed an improved tissue clearing method for mouse embryonic and early postnatal mandibles, designated as a mini Transparent Embedding Solvent System (miniTESOS), based on the Transparent Embedding Solvent System (TESOS). We applied this method to the K14-Cre;Ai14 mouse line to systematically investigate the spatiotemporal dynamics of HERS at the cellular level during the development of the roots of mandibular first molars (MM1) and mandibular second molars (MM2). Additionally, using MM1 as a model, we quantitatively investigated the spatiotemporal changes in HERS in the root bifurcation region during the development of two-rooted teeth. In the early stages of root development, differences in growth rates and developmental patterns between MM1 and MM2 were observed in the mesiodistal and buccolingual directions, from the initiation to the fusion of buccal and lingual HERS. In the elongation stage of two-rooted teeth, continuous HERS was found exclusively at the leading edge of the root, gradually decreasing in length as the root extended. In the root bifurcation area, HERS undergoes four developmental stages: initiation, elongation, contact, and complete fragmentation, each characterized by specific morphological features. This study improves the understanding of the alterations in HERS during root development and summarizes its developmental pattern in the root bifurcation region. The miniTESOS tissue clearing method provides a new strategy to investigate tooth development.

Predictors of surgical difficulty in upper third molar removal: a prospective cohort study.

Upper third molar (U3M) removal is a common surgical procedure. The aims of this study were to assess the patient-specific, radiological and surgical factors related to the difficulty of U3M removal, and to determine the incidence of intraoperative and postoperative complications. A prospective cohort study was carried out in adult patients undergoing U3M removal. Operative time, surgeon-reported difficulty and the Parant classification were used to assess extraction difficulty. Clinical, radiological and surgical factors were recorded to determine their relationship with surgical difficulty. A descriptive, bivariate and multivariate statistical analysis was carried out. A total of 250 patients were included. The mean operative time was 10.4 (±12.3) minutes, mean surgeon-reported difficulty was 3.2/10 (±2.3). The multivariate analysis showed greater impaction against the second molar and greater soft tissue and bony impaction to significantly increase operative time and surgeon-perceived difficulty. Additionally, surgeon experience was related to perceived difficulty. The overall incidence of intraoperative complications was 0.8%, and no postoperative events were recorded. Upper third molars in close relation with the roots of the adjacent second molar and with soft tissue and bony impaction are significantly more difficult to extract. Perceived difficulty was related to surgeon experience. This procedure appears to produce few intra- and postoperative complications.

Analysis of the anatomical relationship between the roots of three lower molars with the lingual bone plate and the mandibular canal using cone beam computed tomography

Odontectomy of the inferior wisdom teeth is considered to be one of the most frequently performed dental surgeries. It is certain that in order to prevent possible complications, the oral surgeon must have extensive knowledge regarding the anatomy of the region, possible intra– and postoperative risks, as well as treatment methods that would minimize the occurrence of complications. Of course, a key aspect in choosing the treatment technique and method is represented by the paraclinical investigations, and currently CBCT is considered to be the “golden” standard in visualizing the relationship of the third inferior molars to the neighboring anatomical structures, a fact that significantly contributes to the optimization the provision of dental surgical assistance. The purpose of this study was to reveal the role of the CBCT paraclinical radiological examination in the pre–surgical evaluation of the anatomical relationships of the roots of the lower third molars with the neighboring anatomical elements for the prophylaxis of postextractional complications. Material and methods. The prospective clinical study was based on the visualization of tomographic sections of 116 CBCTs, with a total of 160 inferior wisdom teeth, analyzing various study variables such as the relationship of the inferior wisdom teeth roots to the mandibular canal, to the lingual bony plate, root morphology, etc., with their subsequent statistical analysis. Results and discussion. The extraction of the lower wisdom teeth can be associated with the occurrence of various complications such as the association of postoperative infection, dislodging the teeth into the neighboring spaces, nerve damage. It is important to use preoperatively both the predictability scale of the difficulty of extraction of inferior third molar and the three–dimensional paraclinical investigations in order to plan a treatment plan involving low risks of intra– and postoperative complications. Conclusions. The use of three–dimensional paraclinical investigations such as CBCT are absolutely necessary both for visualizing the relationship between anatomical structures and for planning complex clinical cases.

Presence of radix entomolaris in primary mandibular first molars: A review of rare entity

Numerous developmental anomalies with respect to crown and root are commonly seen in permanent dentition and while rarely in the primary dentition. Radix entomolaris (RE), an extra root seen on the distolingual aspect of mandibular molars, is one such aberration found. The presence of extra root in primary mandibular first molars is of extreme rarity and such two reports its significance had been discussed. Two children of 5- and 7 years old reported to the pediatric and preventive dentistry department with a chief complaint of pain in the right and left mandibular back teeth region, respectively. A diagnosis of chronic irreversible pulpitis was made in both cases with the accidental appraisal of RE in both the primary first molars on intraoral periapical radiographs. Standard pulpectomy was performed in both cases. Pediatric dentists as well as clinicians should update regarding the abnormal morphologies of primary molars and its diagnostic including treatment strategies.

Інтегральний аналіз клінічних та рентген- антропометричних предикторів тонкого фенотипу тканин пародонту як фактора ризику пародонтальних ускладнень ортодонтичного лікування

Resume: In the article, it was carried out a study of the most clinical predictors of the thin biotype of periodontal tissue, as a consequence of healing in predicting the possible complications of orthodontic treatment. And to itself: I have a mucus alveolar growth with zones of ischemia; small child of an empty company; prominence of roots, lower frontal teeth; short lips ties and tongue tie; manifestations of additional folds of vestibule of the mouth; injection of blood vessels on the alveolar ridge and on the inner surface of the lips and cheek; sharply folded alveolar ridge; change in the height of the interdental papillae and change in the shape of their tops; the presence of wide and narrow recesses is clear. Statistically priming of thin and small X-ray anthropometric predictors of thin biotype of periodontal tissues: thin and long roots of lower cuts; half-moon-like tops of the roots of the cuts and the cleavages of the lower slit; large drawing of trabeculae of spongy cystic tissue; straight, or so, that the roots of the first permanent molars of the lower fissure diverge; a sharp deficit in the height of the body of the lower crack, especially in the vineyards. Key words: periodontal tissue, orthodontic treatment, periodontal tissue biotype, orthopantomography

Assessment of fracture resistance of mesial roots of mandibular molars prepared by NiTi rotary files of different tapers and alloys (A Comparative in-vitro study)

Assessment of fracture resistance of mesial roots of mandibular molars prepared by NiTi rotary files of different tapers and alloys (A Comparative in-vitro study)

Assessment of Anatomical Dentin Thickness in Mandibular First Molar: An In Vivo Cone-Beam Computed Tomographic Study.

To determine the minimum dentin thickness in the mesial and distal walls of the mesiobuccal (MB) and mesiolingual (ML) canals of the mandibular first molars using cone-beam computed tomography (CBCT). CBCT examinations of 624 mandibular first molars from an Indian subpopulation were analyzed. The mesial and distal minimum dentin thickness was evaluated in 1 mm intervals apical to the furcation area. Independent t-test was used to analyze the data (α = 0.05). Using Cohen's kappa coefficient, the interexaminer and intraexaminer reliability was evaluated. The mesial dentin thickness was significantly higher than the distal dentin thickness for MB and ML canals (P=0.01). The average dentin thickness in the distal and mesial plane of the MB canal was 1.15 ± 0.15 mm and 1.52 ± 0.19 mm at the 1 mm level and 0.83 ± 0.13 and 1.08 ± 0.18 at the 5 mm level, respectively. For the ML canal, the average dentin thickness in the distal plane and the mesial plane was 1.24 ± 0.18 mm and 1.44 ± 0.21 at the 1 mm level and 0.91 ± 0.16 and 1.01 ± 0.17 at the 5 mm level, respectively. Statistical analysis between the MB and ML canals showed significant differences in the dentin thickness at 4 and 5 mm levels in both the distal and the mesial planes (P=0.01). In more than 85% of the cases, the minimum dentin thickness was seen at the 5 mm level in both the distal and mesial planes in MB and ML canals. The distal planes of the mesiolingual and mesiobuccal canals were thinner in most cases, making the distal surface more prone to iatrogenic perforations. Considerably, at 4 and 5 mm from the furcation, the distal wall was significantly thinner than the mesial walls. Understanding the anatomy of the danger zone in the mesial roots of the mandibular first molars may serve to minimize the risk of endodontic mishaps such as strip perforations.

Cystic Extrafollicular Adenomatoid Odontogenic Tumour: A Case Report and Pictorial Update

Adenomatoid Odontogenic Tumour (AOT) constitutes about 5% of all odontogenic tumours and is most commonly seen in young females, in association with impacted maxillary canines in a Dentigerous Cyst (DC) like relationship. Extrafollicular AOT is an uncommon variant seen unassociated with impacted teeth. Rare cystic presentation is reported with most cases seen arising from or in association with DC. Here, the authors present a case of extrafollicular AOT in a 29-year-old Dravidian male, who reported with a chief complaint of swelling of lower anterior jaw region. Radiographically, a well-defined radiolucent lesion was noted extending from mesial aspect of the roots of right mandibular second molar, crossing the midline to involve the body of mandible till mesial aspect of lower left canine. There was evidence of cortical perforation. The lesion was excised and sent for histopathological evaluation. Histopathologically, the lesion was diagnosed as cystic AOT-extrafollicular variant. There was adequate healing and no signs of recurrence or residual disease were noted 18 months after the surgery. The present case is a unique presentation of cystic extrafollicular AOT with pictorial demonstration and detailed explanation of its pathogenesis.

Filling Material Bond Strength to Dentin Is Positively Influenced by the Agitation of Endodontic Final Irrigating Solutions.

The final step of irrigation has been considered to of increase the bonding strength of filling material to dentin. This study investigated the impact of three final-step irrigation methods on the endodontic sealer bond strength to dentin by using a micro push-out test. Palatal roots of human maxillary molars were cleaned and shaped and randomly divided in six groups (n=15) according to the final-step irrigation method and the type of root canal sealer used. The solutions used for the final-step irrigation were 17% ethylenediaminetetraacetic acid and 2.5% sodium hypochlorite, which underwent three methods: 1) syringe-needle irrigation/conventional, 2) passive ultrasonic irrigation, and 3) XP-endo Finisher agitation. The root canal sealers used were: EndoSequence BC Sealer, and AH-Plus sealer. Roots were obturated with the single cone technique and then, cross-sectioned in 2-mm-thick slices (3 slices from each root). Push-out test was performed on the sliced specimens (cervical, middle, and apical thirds) with a universal testing machine. Bond strength values were recorded in megapascal (MPa). Subsequently, each specimen was longitudinally split to verify the type of failure. Data analysis was performed using Johnson transformation, three-way analysis of variance, Tukey's post-hoc tests, and the partial Eta squared test. There were significant differences in bond strength between the sealers [AH: 4.46±2.24 and BC: 3.47±2.19 MPa (P<0.001)]; between final-step irrigation methods [passive ultrasonic irrigation: 4.52±2.25, XP-endo Finisher: 3.93±3.93 and syringe-needle irrigation/conventional: 3.37±2.51 MPa (P<0.001)], and between the root canal thirds represented by the sliced specimens [cervical: 5.45±2.39, middle: 4.14±1.99 and apical: 2.30±1.30 MPa (P<0.001)]. The interaction between the variables had no significance (P>0.05). Agitation of the final irrigating solution may improve the bonding of the sealer to canal walls. AH-Plus sealer had the highest bond strength. The bond strength reduced significantly towards the apical third.

Assessment of the Effect of Different Irrigation Protocols on the Penetration of Irrigation Solution into Simulated Lateral Canals (In Vitro Study).

To compare the effectiveness of lateral canal irrigation penetration by conventional needle, passive ultrasonic, sonic endo activator, and Erbium laser (2780nm). A total of 40 palatal roots of human maxillary first molars were collected and instrumented at a working length of 12 mm by an X1-X4 rotary Protaper Next system (Dentsply, Maillefer, Ballaigues, Switzerland) using the crown-down technique. Artificial lateral canals were made at 2, 4, and 6 mm from the apex on mesial and distal sides using an ISO rotary reamer (Dentsply, Maillefer, Ballaigues, Switzerland; #10 for mesial, #08 for distal). The samples were then cleared using methyl salicylate. A solution of black ink and normal saline was used as an irrigant for the root canal. The percentages of the penetration of the ink into the lateral canals were measured using a stereomicroscope (Q-Scope, Arnhem, The Netherlands) with the aid of program Image J. The Tukey test is used to assess the significant difference between intragroup and intergroup comparisons of different thirds, and the T-test is used to assess the significant difference between every two groups and for the mesial and distal sides of each group. The level of significance was set at 0.05. Results showed that none of the activation techniques used resulted in complete lateral canal penetrations; however, on both sides at all thirds, the Erbium laser (2780 nm) achieved the highest results with a highly significant statistical difference (p=0.05) with all other groups, and the least penetration was in the conventional needle group. The size of the lateral canal is a restricting factor for all activation methods; the best results can be achieved by laser. Conventional needles cannot be used alone to disinfect complex canal anatomy; however, passive ultrasonic and sonic endo activator activations can produce comparable results.