Palatal Roots Of Maxillary Molars Research Articles

Microbial composition and diversity in intraradicular biofilm formed in situ: New concepts based on next-generation sequencing.

This study aimed to characterize the taxonomic composition of intraradicular multispecies biofilms (IMB) formed in situ in a model to reproduce clinical conditions. Twelve palatal roots of maxillary molars had its canals prepared. Two roots were randomly selected to sterility control. Ten intraoral prosthetic appliances with lateral slots were fabricated. The roots were positioned in the slots with the canal access open to the oral cavity. Eight volunteers wore the appliance for 21 days, and two wore it at two different time points. One root from each appliance was removed and stored at -20°C until DNA extraction and sequencing (n=10). Biofilm was analyzed using next-generation sequencing and bioinformatics. The V4 hyper-variable region of the 16SrRNA gene was amplified and sequenced. For data analyses, the mothur pipeline was used for 16SrRNA processing, and subsequent analyses of the sequence dataset were performed in R using the Microbiome Analyst R package. The taxonomy-based analysis of bacterial communities identified 562 operational taxonomic units (OTUs), which belonged to 93 genera, 44 families, and 8 phyla. Bacterial colonization was different for each biofilm, and samples did not have the same group of bacteria. Alpha and beta diversity analysis revealed some general patterns of sample clustering. A core microbiome of prevalent OTUs and genera was identified. IMBs were heterogeneous when analyzed individually, but some diversity patterns were found after sample clustering. The experimental model seemed to reproduce the actual biofilm composition in endodontic infections, which suggests that it may be used to evaluate disinfection protocols.

Microbial composition and diversity in intraradicular biofilm formed in situ: New concepts based on next-generation sequencing.

This study aimed to characterize the taxonomic composition of intraradicular multispecies biofilms (IMBs) formed in situ in a model to reproduce clinical conditions. Twelve palatal roots of maxillary molars had its canals prepared. Two roots were randomly selected to sterility control. Ten intraoral prosthetic appliances with lateral slots were fabricated. The roots were positioned in the slots with the canal access open to the oral cavity. Eight volunteers wore the appliance for 21 days, and two wore it at two different time points. One root from each appliance was removed and stored at -20°C until DNA extraction and sequencing (n=10). Biofilm was analyzed using next-generation sequencing and bioinformatics. The V4 hyper-variable region of the 16SrRNA gene was amplified and sequenced. For data analyses, the mothur pipeline was used for 16SrRNA processing, and subsequent analyses of the sequence dataset were performed in R using the MicrobiomeAnalyst R package. The taxonomy-based analysis of bacterial communities identified 562 operational taxonomic units (OTUs), which belonged to 93 genera, 44 families, and 8 phyla. Bacterial colonization was different for each biofilm, and samples did not have the same group of bacteria. Alpha and beta diversity analysis revealed some general patterns of sample clustering. A core microbiome of prevalent OTUs and genera was identified. IMBs were heterogeneous when analyzed individually, but some diversity patterns were found after sample clustering. The experimental model seemed to reproduce the actual biofilm composition in endodontic infections, which suggests that it may be used to evaluate disinfection protocols.

Comparative Evaluation of Microhardness, Smear Layer Removal Efficacy and Depth of Penetration Using Punica granatum, Emblica officinalis and Sodium Hypochlorite As Endodontic Irrigants: An In Vitro Study.

Introduction Root canal morphology tends to be complicated by natureand dealing with this intricacy can be challenging because it makes it difficult to completely disinfect the root canal space.The success of root canal therapy is also determined by the biomechanical preparation of the canal with the application of instruments and irrigating solutions.Due to the fact that the root dentin surface continues to interact with the irrigating solution during preparation, it's critical to evaluate the mechanical characteristics and smear layer removal. Though sodium hypochlorite (NaOCl) is the most commonly used irrigant due to its tissue-dissolving abilities, it has certain drawbacks which include the inability to remove the smear layer and also affects the mechanical properties of root dentin. To overcome these limitations, a variety of herbal substitutes likePunica granatumand Emblica officinaliswhich possess anti-bacterial and anti-fungal properties can be used as endodontic irrigants.Several studies on the anti-bacterial properties of natural irrigants of pomegranateand amla were reported. However, the mechanical properties and smear layer removal of Punica granatum and Emblica officinalis have not been explored in the field of endodontics. Aim The main aim of this in vitro study is to compare and evaluate microhardness, smear layer removal efficacy and depth of penetration of herbal and conventional irrigants. Materials and methods Thirty-six palatal roots of maxillary molars were decoronated and instrumented up to F3. These roots were sectioned longitudinally and divided into three test groups: Group 1: 12.5% Punica granatum;Group 2: 6.25% Emblica officinalis; control: Group 3: 2.5% NaOCl. All specimens were irrigated with 5ml of each irrigant for 5 minutes. Microhardness of root dentin was measured using a Vickers diamond intender, smear layer removal using a scanning electron microscope (SEM) and depth of penetration using a stereomicroscope. The data was analyzed using one-way ANOVAand the inter-group comparison using Tukey's post hoc test. Results Statistical analysis was done using one-way analysis of variance (ANOVA) and Tukey's post hoc test using SPSSsoftware version 17.0 (SPSS Inc., Chicago ). The highest microhardness was seen in Group 1(cervical: 53.8375±1.35956, middle: 53.9875±1.01761, apical: 53.6875± 1.63133)while Group 2(cervical: 43.2750±1.73596, middle: 43.3125±1.17648, apical: 43.8000± ​​​​​​​1.32665) and Group 3 (cervical: 42.7250±​​​​​​​2.93391, middle: 41.9625±​​​​​​​1.66985, apical: 42.0250±​​​​​​​2.21085) showed significant reduction in root dentin hardness. Regardingsmear layer removalGroup 1 (1.3750±​​​​​​​0.51755), and Group 2 (1.2500±​​​​​​​0.46291) reveals greater smear removal in the middle third of the root dentin compared with Group 3 (2.3750±​​​​​​​0.51755), which showed the least smear layer removal. A greater depth of penetration was seen in Group 1 (0.5488± 0.05222) and Group 2 (0.5263±​​​​​​​0.05181)than in Group 3 (0.3087±​​​​​​​0.05743). Conclusion The present study reveals that the least reduction of microhardness was seen in Punica granatum followed by Emblica officinalis and NaOCl. The smear layer removal efficacy and depth of penetration were greater in Punica granatum and Emblica officinalis than in NaOCl. It was concluded that as these herbal irrigants are biocompatible agents, they can be considered for future use in root canal treatment.

Influence of Apical Diameter on Filling Material Extrusion during Retreatment - A Micro-CT and CBCT evaluation.

To investigate whether foraminal widening performed at primary treatment has an effect on the amount of apically extruded obturator material during retreatment and to evaluate the sensitivity of cone beam computed tomography (CBCT) in detecting extruded obturator material. Forty palatal roots of maxillary molars were selected based on micro-CT and divided into two groups (n=20): with foraminal widening (WE) and without foraminal widening (NE). To standardize the apical foramen, all specimens were instrumented to the foramen using the Protaper Next system, up to instrument X3. The WE group was instrumented to the foramen up to instrument X5, and the NE group was instrumented 1 mm lower. The canals were obturated 1 mm below the apical foramen with gutta-percha and AH Plus and stored for 7 days at 37 °C and 95% humidity. Roots were fixed in microtubes filled with 1.5% agar gel. The obturation material was removed with Reciproc R50. Scans of the teeth and agar were performed using micro-CT and CBCT. Comparison between groups and between methods was performed using Mann-Withney test (p ≤0.05). No statistical difference was found when comparing the extruded material between groups using micro-CT (p = 0.589) or CBCT (p = 0.953). CBCT measured a greater volume of extruded material than micro- CT (p = 0.0004). Foraminal widening had no effect on the extrusion of filling material during retreatment. The CBCT favored the evaluation of apically extruded filling material.

Maxillary First Molars with Two Palatal Root Canals

Understanding the anatomical variations in the roots and root canal systems of a tooth is important for the success of root canal treatment. The palatal roots of the maxillary molars have fewer anatomical variations than the other roots, and fewer variations occur in the first molars than in the second molars. This case report describes two distinct cases of maxillary first molars with two palatal canals. For the root canal treatment of teeth with anatomical variations, it is essential to plan specific treatment strategies using cone-beam computed tomography and to execute them using a dental operating microscope. Knowledge of the anatomical variations in the palatal roots of maxillary first molars will help to increase the success rate of root canal treatments.

Prevalence of Apical Periodontitis by Cone Beam Computed Tomography: A Cross Sectional Study

Objective: This study aimed to assess the prevalence of apical periodontics (AP) from a sample of Iraqi adult population by using cone beam computed tomography (CBCT) images. 
 Methods: Two hundred and fifty-one CBCT images (116 male and 135 female) were obtained, 6738 teeth were examined of these patients who attended for dental treatment from January 2017 to June 2018 in the B&R private dental clinic in Sulaimani, Kurdistan region/Iraq. Apical periodontitis was divided according to tooth types (anatomical) in both upper and lower jaw, root canal treatment (RCT) and non-root canal treatment (Non-RCT), affected root by AP, and quality of RCT. Pearson’s chi-square test was used to determine the level of significance (p<0.05).
 Results: Apical periodontitis was found in 294 teeth from 6738 examined teeth, of these, 59.9% of AP incidence was linked to RCT. The percentage of periapical lesions was not significantly different between male and female patients. Among RCT teeth, maxillary teeth were found to be most susceptible to AP (61.92%) compared to mandibular teeth (38.07%). Mesiobuccal root of upper first molar and mesial root of lower first molar were most commonly affected with AP (12.4%). The most reported defects where under filling, followed by missed canal, and pulpotomy which were 32%, 20% and 18 % respectively. Missed upper second mesiobuccal canal presented with a higher percentage of AP (40.6%) and palatal roots of maxillary molars showed the least AP (2.7%). 
 Conclusions: The prevalence of AP was low on population level; however, the prevalence of AP was high in inadequate endodontically treated teeth and increased in teeth with complex anatomy.

Selective Retreatment and Sinus Lift: An Alternative Approach to Surgically Manage the Palatal Roots of Maxillary Molars

Endodontic microsurgery on the palatal root of maxillary molars presents a clinical challenge because of the root position and approximation from the maxillary sinus floor. Attempting a buccal or a palatal approach to address the root is associated with limited accessibility and visibility as well as the risk of injury to the maxillary sinus membrane and/or the greater palatine nerves and vessels. If all the maxillary molar roots require surgical intervention, two flaps may even be needed, which can make the procedure technically more difficult and lengthier. This case report presents 2 clinical cases in which apicoectomy was needed on the palatal roots of maxillary molars. The treatment includes selective nonsurgical retreatment of the palatal root and obturation using a root repair material followed by a surgical intervention from a buccal approach to treat the buccal roots, sinus lift using piezosurgery, and root resection of the palatal root. The approach was successful in both cases without any untoward events. We monitored the radiographic changes using cone-beam computed tomographic imaging immediately after the surgery and at multiple follow-up appointments. The cone-beam computed tomographic images revealed healing of the periapical disease around all the roots up to 14 and 24 months and apical repositioning of the maxillary sinus floor.

Anatomic Analysis of Palatal Roots of Maxillary Molars Using Micro–computed Tomography

IntroductionThe morphology of the palatal root of maxillary first and second molars was analyzed and compared using micro–computed tomographic scanning. MethodsForty-seven extracted maxillary molars were scanned with a micro–computed tomographic device to analyze the palatal radicular dentin dimensions, canal working width, root length, canal curvature, lateral canals, and apical constriction anatomy. Quantitative data were analyzed with mean and standard deviation for first and second molars, respectively. Comparison was made between first and second molars using an unpaired t test. ResultsThe palatal root of maxillary first molars was found to have statistically significantly thinner dentin than second molars on the palatal aspect of the root 8–11 mm from the apex, correlating to the coronal and middle thirds of the root. First molar palatal roots also had a statistically significantly wider canal mesiodistally than second molars at 13–15 mm from the apex, correlating approximately to the level of the cementoenamel junction and pulpal floor. Significant canal curvature was present. These findings suggest the need for conservative coronal flaring and instrumentation. ConclusionsThe absence of an apical constriction in 76.6% of the specimens highlights the importance of creating an apical seat through instrumentation to maintain obturation materials. A minimum master apical file size of 40 is recommended based on preoperative working widths in the apical 0.5–1.0 mm. A root-end resection of 3.5 mm would remove a greater majority of lateral canals.

Three-dimensional assessment of root canal morphology of human deciduous molars using cone beam computed tomography: An In vitro Study

Background: Endodontic treatment involves cleaning, shaping, and obturation of the root canal system which requires knowledge of root canal morphology and its commonly occurring variation. Aim: The aim of the present study was to assess the variations in number and morphology of deciduous molar teeth using cone beam computed tomography (CBCT) an auxiliary imaging modality. Materials and Methods: A total of ninety recently extracted deciduous molar teeth were collected which are divided into four groups: Group I: mandibular first molars (n = 22), Group II: maxillary first molars (n = 18), Group III: mandibular second molars (n = 21), Group IV: maxillary second molars (n = 29). The length of the roots, angulation of the roots, number of the root canals, curvature of the root canals, and the type of root canals were determined using CBCT. Statistical Analysis: Descriptive statistics were used to find out the frequency, mean, standard deviation, and range of all the five parameters. Results: CBCT showed that the distobuccal root of primary maxillary molars had the greatest angulation, whereas, in deciduous mandibular molars, distal root has the greatest angulation. S-shaped canals were more common in the palatal root of maxillary molars, and curved canals were more common in the mesial root in mandibular molars. Conclusions: CBCT was found to be an effective and accurate diagnostic tool which provides an auxiliary imaging technology to assess the root canal morphology of primary teeth.

Root and root canal morphology of third molars in a Jordanian subpopulation

Introduction: The aims of this study were to (1) investigate the root and root canal morphology of human third molars in a Jordanian subpopulation and (2) determine the effect of age, gender, and tooth location on the morphology of these teeth. Materials and Methods: A total of 159 maxillary and mandibular third molars were used in this study. After canal staining and tooth clearing, the specimens were examined, and the following morphological features were recorded: Number of roots and presence of roots fusion, number of canals and their configurations in each root, total number of canals per tooth, and incidence of lateral canals and intercanal communications. Results: The majority (74.2%) of maxillary molars had 3 roots and 3 (55.1%) or 4 (27%) canals while the majority (74.3%) of mandibular molars had 2 roots and 2 (38.6%) or 3 (45.7%) canals. Roots fusion was found in 70.1% of maxillary molars and 40.7% of mandibular molars. Type I canal configuration was the predominant type in distal roots of mandibular molars and distobuccal and palatal roots of maxillary molars. Multiple canals were evident in 36% of the maxillary mesiobuccal roots and 56% of mandibular mesial roots. Single/fused roots showed a wide range of canals number and configurations. The number of roots and canals in both molars did not differ with gender, age, and tooth location. Females had a higher incidence of roots fusion than males and this difference was significant in mandibular molars (P = 0.034). Conclusions: Third molars showed a range of root and canal morphologies. Careful preoperative assessment is essential before commencing root canal treatment on these teeth.

Evaluation of the prevalence of the maxillary molars with two palatal roots by cone-beam CT

To investigate the characteristic of the maxillary molars with two palatal roots and its prevalence by cone-beam computered tomography. Cone-beam CT (CBCT) images of dentitions were collected retrospectively from 528 patients comprising 1957 maxillary molars. The characteristic and prevalence of maxillary molars with two palatal roots was analyzed. The tooth position, sex and unilateral and bilateral occurrence were recorded. The prevalence of two palatal roots was 0.72%(14/1957). Maxillary second molar with two palatal roots was detected in 1.12%(11/979), which showed a statistically higher prevalence than maxillary first molar 0.31%(3/978). This prevalence did not differ with sex or the side(P > 0.05). The mean distance of interorifice from the mesiolpalatal canal to the distopalatal canal was (2.84 ± 0.50) mm, and the angle between two palatal roots was on average (34.6 ± 16.1) °,which were significantly greater than the mean distance of interorifice from the two buccal roots (2.15 ± 0.82) mm and the angle between the two roots was (21.3 ± 12.2) °. The prevalence of maxillary second molars with two palatal roots was higher than that of the first malars. The angle between the two palatal roots brings difficulty to root canal therapy, so the consciousness of double palatal roots of maxillary molars was helpful for clinical operation.

Bond strength to radicular dentin and sealing ability of AH Plus in combination with a bonding agent

Objective. To evaluate the sealing ability and bond strength of AH Plus sealer associated with the hybridization protocol of radicular dentin with Scotchbond Multi Purpose (SB). Materials and methods. Ninety palatal roots of maxillary molars were selected and divided into three groups (n = 30) according to filling protocol (G1, AH Plus/Resilon; G2, SB/AH Plus/Resilon; and G3, AH Plus/Gutta-Percha). In groups in which AH Plus + resin cones were used, dentin was hybridized before applying sealing material. For the bond strength test, 60 roots of bovine teeth were selected. Six holes were made in each root, two in the cervical, middle and apical third of the root. The roles were filled with AH Plus sealer with or without an adhesive system and submitted to push out test and the fracture mode was examined using a stereomicroscope (×32). Results. Statistical analysis showed that ScotchBond Multi Purpose (SB) + Resilon cone + AH Plus group promoted higher sealing ability than the gutta-percha + AH Plus group (p < 0.05). Bond strength was lower with SB application than without it (p < 0.05). A reverse correlation was found between bond strength and sealing ability. The fracture mode methodology revealed 22.77% of adhesive, 11.67% of cohesive and 65.55% of mixture fractures for SBMP/AH Plus protocol, whereas the AH Plus protocol indicated 86.11% of cohesive and 13.89% of mixed fractures. Conclusion. It was concluded that the use of the adhesive system Scotchbond Multi Purpose improved coronal sealing ability of AH Plus, but bond strength of sealer was reduced when adhesive was applied.

Pulp Stone—An Endodontic Challenge: Successful Retrieval of Exceptionally Long Pulp Stones measuring 14 and 9.5 mm from the Palatal Roots of Maxillary Molars

Pulp stones are nodular, calcified masses commonly appearing in the coronal pulp and occasionally extending in radicular pulp. Retrieval of pulp stones remains a challenge for the endodontist as complete cleaning and shaping of root canal system is the bases for successful endodontic therapy. The aim of this case report is to show the retrieval of long pulp stones measuring 14 and 9.5 mm by utilizing synergistic effect of ultrasonics and sodium hypochlorite from the palatal roots of maxillary molars. Such case has not been reported in the literature so far.

Influence of cervical preflaring on determination of apical file size in the palatal roots of maxillary molars

PURPOSE: The aim of this study was to investigate the influence of cervical preflaring in determining the initial apical file (IAF) in the palatal roots of maxillary molars, and to determine the morphologic shape of the canal 1 mm short of the apex. METHODS: After preparing standard access cavities the group 1 received the IAF without cervical preflaring (WCP). In groups 2 to 5, preflaring was performed with Gates-Glidden (GG), Anatomic Endodontics Technology (AET), GT Rotary Files (GT) and LA Axxes (LA), respectively. Each canal was sized using manual K-files, starting with size 08 files, and making passive movements until the WL was reached. File sizes were increased until a binding sensation was felt at the WL. The IAF area and the area of the root canal were measured to verify the percentage occupied by the IAF inside the canal in each sample by SEM. The morphologic shape of the root canal was classified as circular, oval or flattened. Statistical analysis was performed by ANOVA/Tukey test (P GT=AET>GG>WCP. The morphologic shape was predominantly oval. CONCLUSION: The type of cervical preflaring used interferes in the determination of IAF.

The impact of post preparation on the residual dentin thickness of maxillary molars

The oval-shaped palatal roots of maxillary molars usually have smaller cross-sectional diameter in the buccolingual direction. However, the effect of parallel-sided post preparation on the remaining dentin thickness of root canal walls is unknown. The purpose of this study was to investigate, in vitro, the residual dentin thickness (RDT) of palatal roots in maxillary molars after various intracanal procedures for post placement, and to determine the risk of root canal perforation or weakening on different root canal walls at 2 levels, coronal and apical. Fifteen extracted first maxillary molars exhibiting radiographic mesiodistal root canal widths ranging from 3.8 to 4.2 mm, measured at 5 mm from the apex, were selected from a pool of teeth. The teeth were horizontally sectioned at 2 levels, coronal and apical, after being embedded in acrylic resin with the aid of a metal index, allowing identical repositioning of the sectioned parts throughout the study. Each sectioned surface was photographed with a digital camera coupled to a microscope. The palatal roots were subsequently prepared for post placement as follows: endodontic preparation up to file K50, Largo 3 and 4 drills, and ParaPost 4.5 and 5.0. Cross-sections were rephotographed after each step. Image J software was used to measure the RDT of each root wall at both levels, and data were further analyzed with a 3-way ANOVA/General Linear Model (GLM) for repeated measures. The post-hoc Tukey's range test was used to calculate differences in RDT among the 4 root walls at each root level (α=.05). A significant difference was observed among the intracanal procedures (P<.001). At the apical level, RDT was significantly lower after ParaPost preparation than at the coronal level (P=.009). Buccal and palatal walls displayed significantly lower RDT than the mesial and distal walls at both levels (P=.004). Intracanal preparation up to ParaPost 5.0 increased the risk of perforation or weakening of the buccal and palatal walls, especially at the apical level.

Apical Morphology of the Palatal Roots of Maxillary Molars by Using Micro–Computed Tomography

Introduction The apical constriction (AC) has been a traditional landmark as an end point of canal preparation and obturation. However, the morphology and incidence of this structure have not been definitively determined. The purpose of this study was to determine these factors by using a noninvasive technology, micro–computed tomography. Methods Forty extracted maxillary molar palatal roots were separated and mounted. Each root was scanned with micro–computed tomography. Slices from the scan were computer reconstructed by using special software. This rendered each root three-dimensionally “transparent.” Roots were rotated, and the apical canal region was selected. In 2 sessions, trained evaluators identified the AC as to (1) presence (single and tapered) or (2) absence (flaring, parallel, and delta). Evaluator agreement was assessed by Cohen's kappa. Descriptive frequencies were determined for apical constriction presence and morphology. Results Interagreement and intra-agreement of evaluators were good. In regard to frequency of occurrence, most (65%) canals did not demonstrate an AC. The morphology, in order of most to least, was parallel 35%, single 19%, flaring 18%, tapering 15%, and delta 12%. Conclusions From the noninvasive evaluation of our sample it was concluded that an AC was usually not present and that this apical canal region was variable. If this is true with other tooth groups, the AC should not be used as an anatomical marker for preparation and obturation.

Horizontal/oblique root fractures in the palatal root of maxillary molars with associated periodontal destruction: case reports

To report two cases of palatal root fracture in maxillary molars that were successfully managed in the short term by root canal treatment and root amputation. In the first case, a 48-year-old woman with bony destruction and a deep periodontal pocket on the palatal root of tooth 26 (FDI) underwent root canal treatment. Bleeding into the palatal canal and radiolucent lines over the root suggested a fracture. Further evidence was provided by an electronic apex locator. Subsequent surgery confirmed the presence of a horizontal root fracture and the fractured root was removed. In the second case, a 75-year-old woman presented with pain from the left posterior teeth. Clinical examination revealed an oblique root fracture of tooth 27 palatal roots with abscess formation and a deep periodontal pocket. Palatal root amputation and odontoplasty were performed. This was followed by root canal treatment. Both teeth were preserved in the short term and early healing of these two cases was uneventful. Horizontal/oblique root fracture of the palatal root in molars is rare. A combination of periodontal and root canal treatment and palatal root amputation may allow short-term preservation of functional teeth.

Working Length Determination in Palatal Roots of Maxillary Molars

The purpose of this study was to determine if a buccal curvature in the palatal roots of maxillary molars affected the clinician's ability to accurately determine working length. Twenty-seven extracted, human maxillary molars were sorted by palatal root curvatures as J- and C-type, and the angle of curvature was determined. Straight-line access was made and a #20 file was placed into the canal until the tip was visible at the apical foramen then withdrawn. The file, tooth, and calibration wire were radiographed on one image using the RadioVisioGraphy system. Actual (file) and radiographic (tooth) lengths were determined using the RadioVisioGraphy ruler. Radiographic length appeared shorter on average than the actual length. Canal curvatures larger than 25 degrees had differences greater than 0.5 mm. This represents a statistically significant difference between the actual and radiographic lengths as the degree of curvature increases. There was no significant difference between the J- and C- types.

Study of the apices of human permanent teeth with the use of a scanning electron microscope

The apical region of the roots of 38 maxillary incisors, 25 mandibular incisors, 29 maxillary second premolars, 92 mandibular first and second premolars, 12 maxillary first molars, and 17 mandibular first molars were prepared and studied with the use of a scanning electron microscope. The number and size of the main apical foramina, their distance from the anatomic apex, and the existence and size of accessory foramina were recorded, summarized, and statistically analyzed. More than one main foramen was observed in all groups except for the palatal root of maxillary molars and the distal root of mandibular molars. Accessory foramina were also observed in all groups of teeth. The distal roots of mandibular molars had the largest size main foramen (mean value, 392 μm), whereas the maxillary premolars had the largest accessory foramina (mean value, 53.4 μm) and the most complicated apical morphologic makeup. The distance of the main foramen from the anatomic apex never exceeded 1 mm. The highest values were observed at the mandibular incisors (978 μm), the distal root of mandibular molars (818 μm), and the upper premolars (816 μm). All values showed satisfactory fitting to normal distribution.

Preparation of Space for Posting: Effect on Thickness of Canal Walls and Incidence of Perforation in Molars

A total of 150 extracted maxillary and mandibular molars separated into six groups of 25 teeth each were prepared to the size of a 30 endodontic file. Numbers 2, 3, and 4 Peeso drills were used to produce a post cavity preparation in the root canals of these teeth. After use of each size of Peeso drill, the thickness of the canal walls was measured at two levels: the middle level, 4 mm from the canal orifice; and the apical level, 7 mm from the canal orifice. Mean thickness of all walls was determined for each tooth and drill size. The incidence of root perforations and strippings was recorded also. We found that distal roots of mandibular molars and palatal roots of maxillary molars are best suited for post cavity preparation. Most perforations and strippings occurred on the distal walls of mesial roots of mandibular molars or on the proximal walls of the buccal roots of maxillary molars.