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This study aims to investigate the ability of umbilical cord mesenchymal stem cells (UC-MSC) to enhance the regeneration of pulp-dentin complex in immature permanent teeth with irreversible pulpitis. A total of 32 mandibular premolar teeth with immature apices in 5 dogs were used in this in-vivo randomized controlled trial (RCT). Eight healthy teeth without pre-existing pathosis served as the positive control samples and received no treatment, while in another 8 teeth, the pulp was completely extirpated (negative control). Class V cavities were prepared to induce inflammation in the remaining 16 teeth (groups 3 and 4) and the pulp was extirpated 2-4 mm short of the radiographic apex. Of the 16, the 8 teeth in group 4 received 1 mL of cord blood stem cells with a hydrogel scaffold. Blood clots were covered with mineral trioxide aggregates at the cementoenamel junction in the experimental groups, and teeth were filled with RMGI and composite. Three months later, block sections were removed for histologic evaluations for the evaluation of postoperative apical closure, degree of inflammation, and presence of normal pulp tissue. The data were statistically analyzed with the chi-square test (P <.05). All teeth with complete pulp extirpation demonstrated pulpal necrosis with no postoperative closure of their apices, while apical closure was seen in all the teeth in the remaining groups. There was a statistically significant (P <.001) difference in the presence of inflammation and normal pulp tissue between the experimental groups. The teeth in group 3 showed normal pulp tissue extending to the level of MTA, but there was inflammation within the canal space. In contrast, the teeth in the UC-MSC group demonstrated organized, normal pulp tissue with no inflammation. Based on these results, the regeneration of the pulp-dentin complex is possible with no inflammation when UC-MSCs are used and 2-4 mm of the apical pulp remains intact in immature teeth with irreversible pulpitis. [ABSTRACT FROM AUTHOR]

This study aimed to assess the fracture resistance of mandibular first molars after preparation with 3 different access cavity designs and 2 rotary systems using finite element analysis. Six 3-dimensionally printed mandibular first molars simulating natural teeth received traditional, conservative, and ultraconservative (truss) access cavity preparations. The root canals in each group were instrumented with either XP-Endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) or TruNatomy (Dentsply Sirona, Ballaigues, Switzerland) rotary files. The models were individually digitized, and micro–computed tomographic scans were transferred to Mimics software (Materialise NV, Leuven, Belgium) to create a geometric model of the tooth. The designed model was exported to 3-matic software (Materialise NV), and STL files were transferred to Geomagic Design X (3D Systems, Rock Hill, SC). Point cloud data were used for surfacing and transferred to ANSYS software (Ansys, Canonsburg, PA). A 200-N superficial force was applied vertically to the buccal cusps and central fossa, and the maximum and minimum equivalent von Mises stress values were calculated and reported. The traditional and ultraconservative access cavity designs yielded the highest and the lowest von Mises stress values, respectively. In the ultraconservative cavity design, the stress values in pericervical dentin were lower in canal preparation with TruNatomy compared with XP-Endo Shaper. In the traditional and conservative cavity designs, stress was lower in the first 2 mm from the cementoenamel junction in the XP-Endo Shaper group and in the next 3 mm in the TruNatomy group. Stress was lower in the ultraconservative and conservative cavity designs compared with the traditional design. Also, root canal preparation with TruNatomy yielded lower stress values in general compared with XP-Endo Shaper. [ABSTRACT FROM AUTHOR]

A rare case of extensive multiple idiopathic cervical root resorption with potential genetic predisposition was presented. A heathy 19-year-old Chinese male with no contributory medical or family/social history complained of pain during mastication that lasted for several months. Oral examination identified 7 missing teeth and external cervical root resorption involving 9 teeth. Comparison of orthopantomograms taken in May 2021 and February 2022 identified that cervical root resorption occurred in 22 teeth. Resorption commenced at the cementoenamel junction and progressed rapidly over the 9-month period. Laboratory test results were within normal limits. Trio-based whole-exome sequencing showed a missense mutation c.5630 C > T in the filamin A (FLNA) gene at chromosome X of the subject. This is suggestive of the possibility of sex-linked recessive inheritance. This is the first study to report FLNA mutation in human subjects with cervical root resorption involving multiple teeth. [ABSTRACT FROM AUTHOR]

Some evidence suggests that teeth treated with endodontic surgery and considered to have healed over the short term are seen to relapse when evaluated again after 3 or more years. However, long-term evidence is limited. This study compares healing after endodontic microsurgery over long-term (5–9 years) vs middle-term (1–4 years) follow-up and assesses the influence of different healing predictors over time. A retrospective study was made, comparing the endodontic microsurgery healing rates after 1–4 vs 5–9 years of follow-up. Healing was assessed based on clinical and radiographic parameters. Simple binary logistic regression models were used to analyze the influence of patient age and gender, the type of tooth, previous radiographic lesion size, apical extent of previous root canal filling, the presence of a post, type of restoration, and interproximal bone level upon the endodontic microsurgery healing rate. A sensitivity analysis was used excluding cases of vertical root fracture. Two calibrated observers independently evaluated the periapical radiographs. A total of 332 patients (60% women and 40% men) were included in the study. Of the 332 analyzed teeth, 198 were subjected to middle-term follow-up (1–4 years), with a healing rate of 86.9%, while 134 were subjected to long-term follow-up (5–9 years), with a healing rate of 67.2%. There were no statistically significant differences in terms of gender, age, type of tooth, size of the lesion, apical extent of previous root canal filling, presence of a post, or type of restoration. The regression models identified 2 statistically significant associations: cohort and interproximal bone level (P <.05). A success rate of 86.9% was recorded after 1-4 years of follow-up, vs 67.2% after 5–9 years. Excluding cases of vertical root fractures, in the shortest follow-up cohort (1–4 years), the healing rate was 92.5%, vs 82.6% in the cohort with longer follow-up (5–9 years). The prognosis was influenced by the crestal bone level in relation to the cementoenamel junction of the tooth, being significantly poorer when probing depth was >3 mm mesial or distal to the treated tooth. [ABSTRACT FROM AUTHOR]

Circulating blood is a readily available scaffold when enough bleeding cannot be induced from periapical tissues during regenerative endodontic treatments (RETs). The aim of this investigation was to compare the radiographic outcome (ie, linear and 3-dimensional volumetric) of RET using periapical blood or circulating blood as scaffolds in sheep immature mandibular incisors. Thirty-two immature sheep mandibular central incisors were randomly assigned to the following groups (n = 8): the positive control groups, the pulps were removed without any treatment; the periapical blood group, RET was performed using periapical blood as the scaffold; the circulating blood group, RET was performed using circulating blood as the scaffold; and the negative control group, intact teeth without any treatment. After 8 months, micro–computed tomographic images of mandibular blocks were taken to assess the following: root length, root thickness at the midroot and cementoenamel junction levels, and the incidence of apical closure. Root structures were segmented, and root volumes were calculated and analyzed statistically. RET using periapical blood and circulating blood resulted in increases in root length and root wall thickness at the midroot and cementoenamel junction levels, the incidence of apical closure, and root volume (P <.05). There were no significant differences between the RET groups and the negative control group regarding linear measurements (ie, root length, root thickness, and apical closure) (P >.05). The root volumes of the 2 RET groups were similar (P >.05) and were less than those observed in the negative control group (P <.05). There were no significant radiographic differences between the RET groups using periapical blood and circulating blood as scaffolds. RET resulted in less root volume compared with normal root development. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate substance loss and the time required for access cavity preparation (ACP) using the conventional freehand method (CONV) versus a miniaturized dynamic navigation system of real-time guided endodontics (RTGE) in an in vitro model using 3-dimensional–printed teeth. Nine human anterior maxillary teeth were selected and micro–computed tomographic scanned. Root canals were virtually reduced to 2 mm below the cementoenamel junction. The teeth were digitally duplicated and mirrored to yield 6 different models with 6 single-rooted teeth each. The models were 3-dimensionally printed using radiopaque resin and consecutively mounted on a dental mannequin for ACP. Two operators with 12 and 2 years of clinical experience, respectively, received 6 models (36 teeth) each and performed ACP on half of the models using RTGE (after digital planning) and CONV on the other half 2 weeks later. The time was recorded. Postoperative substance loss was measured by cone-beam computed tomographic imaging. The differences in time and substance loss between the methods and operators were evaluated by the t test. Overall, substance loss was significantly lower with RTGE than CONV (mean = 10.5 mm3 vs 29.7 mm3), but both procedures took a similar time per tooth (mean = 195 vs 193 seconds). Operator 1 (more experienced) achieved significantly less substance loss than operator 2 with CONV (mean = 19.9 vs 39.4 mm3) but not with RTGE (mean = 10.3 vs 10.6 mm3). RTGE is a practicable, substance-sparing method performed in comparable time as CONV. Moreover, RTGE seems to be independent of operator experience. [ABSTRACT FROM AUTHOR]

This study aimed to compare root dentinal microcrack formation after root canal shaping using rotary, reciprocating, and adaptive instruments at different working lengths using micro–computed tomographic imaging. One hundred eighty extracted mature mandibular molar mesial roots with 2 separate canals were selected. The mesial roots were resected at the cementoenamel junction and randomly divided into 4 groups (n = 45) based on the nickel-titanium file system used: ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Gold (Dentsply Maillefer), Twisted File Adaptive (SybronEndo, Orange, CA), and Reciproc Blue (VDW, Munich, Germany). Each of the 4 groups were then subdivided into 3 groups (n = 15) depending on the working length used for root canal preparation (ie, instrumentation 1 mm short, flush, and 1 mm beyond the major apical foramen). The roots were imaged with micro–computed tomographic scanning before and after root canal preparation. The cross-sectional images generated were screened to detect the presence of new microcracks. The ProTaper Universal system significantly increased the number of postinstrumentation microcracks at all working lengths (P ≤.05). No significant increase (P >.05) in postinstrumentation microcracks was observed in the ProTaper Gold, Twisted File Adaptive, or Reciproc Blue groups. Rotary instrumentation induced a higher number of dentinal microcracks compared with reciprocating and adaptive instruments. Instrumentation at different working lengths did not significantly influence the formation of dentinal microcracks. [ABSTRACT FROM AUTHOR]

The purpose of this study was to comprehensively assess by micro–computed tomographic imaging the anatomic features of distolingual (DL) roots and canals in mandibular first molars collected from 1 population. One hundred two specimens were examined for the location and initial direction of the DL canal and the relationship between the distance of apical deviation and the angle of root curvature. All DL roots had only 1 canal. A new 7-category classification system is proposed for the DL roots of mandibular first molars. Most DL roots were type IV (28 teeth), type III (26 teeth), and type V (25 teeth). The average canal curvature in all root types was over 25°. There was a positive correlation between the angles of root and canal curvature for types II, IV, and V (P <.05) but not for types I and III (P >.05). In the buccolingual view, most DL roots were straight, whereas in the mesiodistal view the root curvature was close to the maximum value. The orifice of the DL canal was 4 times further from the line that bisects a line between the mesiobuccal and mesiolingual canal orifices than the distobuccal canal. The angle between the mesiobuccal-mesiolingual line and the horizontal projection of the coronal third of the DL canal on the pulp floor was 8.1° ± 10.0° and 6.1° ± 8.2° for teeth from the left and right side, respectively. The angle between the inserted simulated file and the cementoenamel junction was 57.9° ± 6.3°. Seventy-three percent of the DL canals had no constriction in the apical area. The DL canals were narrow and had a conical frustum-like shape with a 0.04 taper at the apical portion. The novel classification of the DL roots helps to better understand the clinically challenging anatomy of the root and canal. [ABSTRACT FROM AUTHOR]

The aim of this cone-beam computed tomographic study was to evaluate the association between the mesiobuccal root canal configuration (RCC), interorifice distance (IOD), and the corresponding root length of a permanent maxillary first molar tooth. One hundred cone-beam computed tomographic scans obtained from the computerized data bank of the institute were studied. The IOD between the first mesiobuccal and second mesiobuccal canal was measured in the axial section where the second mesiobuccal canal was first visualized. The root length was measured from the cementoenamel junction to the root apex in the coronal and sagittal section. The associations of these parameters with the RCC (based on Vertucci's classification) were evaluated. The predominant RCC was observed to be Vertucci type II (89%). The mean root length with this configuration was 11.19 ± 1.35 mm. In type IV RCC, the mean root length was 9.13 ± 0.52 mm. A statistically significant association was established between the root length and RCC (P <.05). In roots with type II and type IV RCC, the mean IOD was 2.58 ± 0.04 mm and 2.62 ± 0.1 mm, respectively. No statistically significant relation was established between the IOD and the type of RCC (P >.05). The length of the mesiobuccal root is an important anatomic parameter for predicting the type of RCC in the permanent maxillary first molar tooth. [ABSTRACT FROM AUTHOR]

New tricalcium silicate cements have been shown to induce less coronal discoloration. The purpose of this in vitro study was to evaluate the degree of color change induced by various silicate materials in the presence and absence of blood. One hundred human extracted anterior single-canal teeth were sectioned to standardized root lengths, accessed, and instrumented. Eight random experimental groups and 2 control groups were created wherein specimens were filled with experimental materials below the buccal cementoenamel junction as follows: EndoSequence RRM putty (Brasseler USA, Savannah, GA), EndoSequence RRM fast set putty (Brasseler USA), Biodentine (Septodont, Saint-Maur-des-Fossés, France), and white mineral trioxide aggregate (Dentsply Sirona, York, PA) either with the presence or absence of blood. Blood-only and saline-only samples were used for the positive and negative controls. After incubation in 100% humidity at 37°C, color changes were evaluated with a spectrophotometer (Ocean Optics, Dunedin, FL) on days 0, 30, 60, and 180 after material placement. Data were transformed into Commission International de I'Eclairage's L∗a∗b color values, and corresponding ΔE values were calculated. The 1-way analysis of variance test was performed for statistical analysis. Discoloration was observed in all specimens in the presence of blood. There was no statistical significance when comparing different materials in contact with blood. Intragroup observation at various time points, Biodentine, and EndoSequence RRM fast set putty showed significant difference between the presence and absence of blood at 180 days (P <.05). Contamination with blood of tricalcium silicate materials has the potential to cause coronal tooth discoloration. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the impact of the incision type, with or without a coronally repositioning flap (CRF), on soft tissue healing and crestal bone remodeling after endodontic microsurgery (EMS). Clinical pictures and cone-beam computed tomography images from 47 patients (120 teeth) taken before surgery and at the follow-up appointment were included in this study. Clinical pictures were qualitatively evaluated by 2 endodontists for the gingival marginal level (GML) (recession, same position, or coronal root coverage), papillary height (same position/receded), and for presence/absence of scars for each tooth. Cone-beam computed tomography images were used to calculate the changes in the distance between the cementoenamel junction and the crestal bone level (CBL) between the preoperative and follow-up scans. Statistical analyses were performed to determine a correlation between patient-related factors (age, sex, tooth type, position, and presence/absence of a crown), incision techniques, and changes within the CBL. Gingival recession was more prevalent in mandibular teeth, molar teeth, and teeth that received intrasulcular or papilla-based incisions (P <.05). Scar formation was affected by the flap design (P <.05). CRF was the only technique resulting in coronal root coverage (P <.05). There were no changes observed in the papillary height between the various flap designs. There was also no statistically significant difference in the crestal bone height between the preoperative and follow-up scan measurements (P >.05). Soft tissue changes are evident after EMS and can be affected by the flap design selected, as well as the site being treated. Application of CRF can improve the position of GML after EMS. There are insignificant changes within the CBL at the facial aspect of the root after EMS. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the fracture resistance and fracture patterns of endodontically treated maxillary premolars with wedge-shaped cervical lesions restored with a resin composite core with or without a fiber post under nonaxial loading. Sixty extracted human maxillary premolars with 2 root canals were randomly allocated into 4 groups (n = 15). Forty-five teeth were prepared with a wedge-shaped lesion at the buccal cervical area and root canal treatment. There were 3 restoration groups: no restoration, restoration with a resin composite core, and restoration with a resin composite core and a fiber post. Intact teeth served as the control group. All teeth were subjected to thermocycling and cyclic loading. A 45° compressive load was applied to the palatal plane of the buccal cusp until tooth fracture. The fracture resistance and facture patterns were analyzed using 1-way analysis of variance and the chi-square test (α = 0.05), respectively. The no restoration group demonstrated the lowest fracture resistance and was significantly different from the other groups (P <.001). The intact teeth presented the highest fracture resistance, which was not significantly different from the restoration with a resin composite core and a fiber post group (P >.05). The failure patterns were significantly different between groups (P <.001). Most intact teeth fractured coronally to the cementoenamel junction level, whereas most teeth in the other groups fractured at the gingival margin of the cervical lesion. Endodontically treated maxillary premolars with wedge-shaped cervical lesions restored with fiber posts and a resin composite cores had a fracture resistance equivalent to intact teeth. However, their fracture patterns were not improved by the fiber post and a resin composite core. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the tooth structure theoretically required to be removed in the coronal and cervical regions to accomplish 3 different endodontic access preparations in a novel digital model. The deviation of the center of access cavity from the central fossa will also be measured and compared among the 3 endodontic cavity designs, which in turn may serve as suggested points of entry for different access openings. Twenty-one maxillary molars and 15 mandibular molars were selected and 3-dimensionally imaged with cone-beam computed tomographic imaging. Three-dimensional (3D) volume reconstructions were made and converted into stereolithography files. Digital access cavity preparation was performed on each 3D reconstruction model with the 3 most commonly used endodontic access preparations: minimally invasive (MI), modified straight-line (MS), and traditional straight-line (TS) techniques. After the access cavity outlines were determined, digital sectioning of each reconstructed 3D tooth model was performed orthogonal to the long axis of the tooth at 3 levels: (1) passing through the central fossa, (2) 1.5 mm apical to the central fossa, and (3) 2 mm apical to the cementoenamel junction. The linear distance from the centroid of the access opening to the central fossa was measured to calculate the point of entry, and the amount of tooth structure removal at the pericervical area was measured to calculate the theoretically minimum amount of linear dentin removal required. Two-way repeated measures analysis of variance was performed for the interactions between different access designs and the amount of cervical dentin removal. Other data were statistically analyzed with 1-way repeated measures analysis of variance. The Tukey post hoc test was used for multiple comparisons. Significance was set at.05. The amount of deviation of the center of the access cavity from the central fossa in all test groups was less than 1 mm. The dimensions of access openings differed significantly among the 3 access forms (TS > MS > MI, P <.0001). The amount of required cervical dentin removal was the greatest in the TS method followed by the MS and MI methods (P <.0001). The central fossa could serve as good starting points in all access preparations in both maxillary and mandibular molars. Dentin removal in the coronal and cervical regions was the greatest in the TS design followed by the MS and MI designs. When comparing different canals in the same access form, less cervical dentin was sacrificed in the palatal canals of maxillary molars and the distal canals of mandibular molars. [ABSTRACT FROM AUTHOR]

The palatogingival groove is a developmental anomaly that typically starts near the cingulum of the maxillary incisors and extends along the roots at varying lengths and depths. Severe grooves that extend to the root apex often lead to complex combined periodontal-endodontic lesions. There are various therapeutic options available for these cases; however, the prognosis is unfavorable. Here, we report the successful surgical treatment of 3 cases of maxillary lateral incisors with severe palatogingival grooves using intentional replantation with a 2-segment restoration method. The teeth were gently extracted, resulting in minimal damage to the periodontal ligament. Under a dental operating microscope, 3 mm of the root end was resected. The palatogingival groove was removed, and root-end preparation was performed with a #700 fissure bur. The groove cavity was connected with root-end cavity to form a class II cavity. The cavity was then filled using a 2-segment restoration method (ie, dividing the cavity into 2 parts by the cementoenamel junction, the coronal portion was filled with a flowable composite while the radicular portion, including the root-end cavity, was filled with bioceramics). The tooth was then replanted into its alveolar bone and splinted with a flexible splint for 7 days. The sinus tract was closed at the 1-week postoperative visit. During subsequent recalls, the teeth showed almost complete periapical healing. In summary, intentional replantation with a 2-segment restoration method is a viable treatment modality for single-rooted teeth with a severe palatogingival groove that extends to the root apex. [ABSTRACT FROM AUTHOR]

The morphology of the palatal root of maxillary first and second molars was analyzed and compared using micro–computed tomographic scanning. Forty-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. The 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. The 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. • 1st molars have thinner palatal dentin midroot & wider M/D canal width at CEJ. • Majority of curvatures were greater than 20 degrees and localized at midroot. • No apical constriction in 76.6% of samples. • A minimum MAF of 40/0.04 is recommended based on pre-op canal working widths. • A 3.5mm surgical resection will remove more lateral canals than 3mm. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the morphologic features of radicular groove accessory canals (RGACs) in mandibular first premolars and their relationship to root anatomy by micro–computed tomographic imaging. A total of 154 single-rooted mandibular first premolars with radicular grooves were selected. The teeth were scanned by micro–computed tomographic imaging, and the following parameters were recorded: (1) the presence of RGACs, (2) the origin of RGACs, (3) the position of the RGAC foramen in the groove in relation to root length, (4) the foramen diameter, (5) the type of groove present according to the Arizona State University dental anthropology scoring system (ASUDAS), and (6) the type of anatomy present according to Vertucci's classification. The data were recorded and statistically analyzed using the chi-square test (P <.05). The incidence of RGACs in the teeth was 49.9%. The average distance from the cementoenamel junction plane to the RGAC foramen was 8.83 ± 2.53 mm, and the majority of the RGAC foramina were located in the middle third. Regarding the severity of the groove, the presence of RGACs was significantly higher for groups ASUDAS 3 and 4 compared with ASUDAS 1 and 2 (85.7% and 14.3%, respectively). The presence of at least 1 RGAC was greatest for Vertucci type V (46%) and for more complex types (46%) when compared with Vertucci types I and III. Mandibular first premolars with radicular grooves often present with RGACs. An association between the internal and external anatomy and the presence of RGACs was detected in this study. [ABSTRACT FROM AUTHOR]

Introduction Creating a glide path before root canal preparation with nickel-titanium rotary files is essential to prevent the file fracture and to maintain the original root canal configuration. Both rotary glide path files and manual K-files are used to create a glide path. The aim of this study was to compare the amount of apically extruded debris after using different glide path files before preparing curved root canals with the WaveOne Gold single-file reciprocating system (Dentsply Maillefer, Ballaigues, Switzerland). Methods Sixty extracted mandibular first molar teeth with curved mesial roots were selected for this study. The mesial roots of the teeth were removed from the cementoenamel junction. Cone-beam computed tomographic imaging was used to evaluate the curvature of the mesial root canals. Specimens were randomly divided into 6 experimental groups according to the root canal preparation ( n = 10): group G-File, a glide path with G-Files (Micro-Mega, Besancon, France) + WaveOne Gold preparation; group One G, a glide path with One G (Micro-Mega, Besancon, France) + WaveOne Gold preparation; group ProGlider, a glide path with ProGlider (Dentsply Maillefer) + WaveOne Gold preparation; group PathFile, a glide path with PathFiles (Dentsply Maillefer) + WaveOne Gold; group K-files, a glide path with a K-file + WaveOne Gold preparation; and group without a glide path, WaveOne Gold preparation without a glide path file. Roots were attached to preweighed Eppendorf tubes. All instruments were used according to the manufacturers' instructions. During root canal preparation, a total of 8 mL distilled water was used for each specimen. Apically extruded debris was collected in Eppendorf tubes. After the completion of root canal preparation, Eppendorf tubes were removed from the specimens and stored in an incubator at 68°C for 5 days. Eppendorf tubes were weighed after evaporation to calculate the amount of extruded debris. The data were statistically analyzed with 1-way analysis of variance and post hoc Tukey honest significant difference tests ( P = .05). Results A statistically significant difference was observed between the One G and K-File groups. The One G group was associated with significantly less debris extrusion than the K-file group. There was no statistically significant difference between K-files and ProGlider, G-Files, PathFiles, and WaveOne Gold without a glide path, and also there was no statistically significant difference between One G and ProGlider, G-Files, PathFiles, and WaveOne Gold without a glide path. All experimental groups caused apical debris extrusion. Conclusions Under the conditions of this in vitro study, all rotary path file systems were associated with similar apical debris extrusion before preparing root canals with the WaveOne Gold single-file reciprocating system. K-files caused more apically extruded debris than the One G files. [ABSTRACT FROM AUTHOR]

Introduction This study aimed to analyze the external and internal morphologies of 3-rooted maxillary first premolars using cone-beam computed tomographic (CBCT) imaging. Methods Fifty-six three-rooted maxillary first premolars were imaged by CBCT imaging and classified into 4 groups on the basis of external root morphology. Internal morphologic features, including the shapes of the buccal and palatal orifices and distances of bifurcation of the buccal-palatal and mesiobuccal-distobuccal root canals from the cementoenamel junction (CEJ), were measured. Results The teeth were classified into 4 groups on the basis of external morphology: group A, separation of the buccal and palatal roots with bifurcation of the former into the mesiobuccal and distobuccal roots ( n = 22); group B, fusion of 2 buccal roots with the palatal root being separate ( n = 19); group C, complete or partial fusion of the distobuccal and palatal roots ( n = 9); and group D, fusion of all 3 roots ( n = 6). The buccal orifice was mainly triangular/heart shaped. The distance of bifurcation of the buccal-palatal root canals from the CEJ in group A differed significantly from those in groups B and C ( P < .05). There were significant differences in the distance of bifurcation of the mesiobuccal-distobuccal root canals from the CEJ among groups A, B, and C ( P < .05). Four teeth exhibited C-shaped root canal systems of different configurations. Conclusions The external and internal morphologies of 3-rooted maxillary first premolars vary considerably. [ABSTRACT FROM AUTHOR]

Introduction The purpose of this study was to compare tooth discoloration that occurs in teeth filled with ProRoot MTA (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) or Biodentine (Septodont, Saint Maur des Fossés, France) over the course of 1 year. Methods Twenty-eight intact premolars were resected 2 mm apical to the cementoenamel junction and the pulp tissues extirpated via the cervical cut. After the preparation of occlusal access to the pulp chamber, specimens were assigned into 4 groups according to a stratified randomization sampling process: group 1, negative control (dry sterile cotton pellet); group 2, positive control (blood-moistened cotton pellet); group 3, ProRoot WMTA (DENTSPLY Tulsa Dental Specialties); and group 4, Biodentine. The experimental materials were condensed into the crowns and the access sealed with glass ionomer restorative cement. Color was assessed at baseline (before placement of the materials), immediately after material filling, after 6 weeks of storage, and after 1 year using the Commission International de I'Eclairage L*a*b* system. Change in color, ΔE, was compared among groups and over time using analysis of variance. Results The 4 groups showed a significant decrease in L* values over time. Differences between Biodentine and WMTA were detected after 1 year, with the greater variation associated with WMTA ( P = .001). The 4 groups presented a significant increase in ΔE from baseline to 1 year. All groups revealed perceptible color changes (ΔE > 2.3) between immediately after material filling and after 6 weeks and after 6 weeks and 1 year. After 1 year, no differences could be detected between Biodentine and WMTA. Conclusions Delayed tooth discoloration was detected for the 2 materials at the 1-year evaluation, but it was more evident for ProRoot MTA than Biodentine. Luminance was the most affected parameter, with a higher decrease for ProRoot MTA. [ABSTRACT FROM AUTHOR]

Introduction Coronal tooth discoloration induced by various endodontic materials was evaluated in vitro . Methods Eighty extracted human maxillary anterior teeth were accessed, instrumented, and sectioned to standardized root lengths of 10 mm below the cementoenamel junction. Pulp chambers were cleaned chemomechanically to ensure complete tissue removal. Specimens were filled with experimental materials in 8 random groups: RRM, EndoSequence RRM putty (Brasseler, Savannah, GA); RRMF, EndoSequence RRM fast set paste (Brasseler); BD, Biodentine (Septodont, Saint-Maur-des-Fossés, France); WMTA, white MTA (Dentsply, York, PA), GMTA, gray MTA (Dentsply); AH+, AH Plus sealer (Dentsply); TAP, triple antibiotic paste (metronidazole, ciprofloxacin, and minocycline); and NF, no filling (negative control group). After incubation in 100% humidity at 37°C, color changes were evaluated with a spectrophotometer (Ocean Optics, Dunedin, FL) on days 0, 7, 30, 60, and 180 after material placement (T0–T180). Data were transformed into Commission International de I'Eclairage's L*a*b color values, and corresponding ΔE values were calculated. Two-way analysis of variance and the Bonferroni method were performed. Results Visual discoloration was observed in all specimens in the GMTA, WMTA, and TAP groups at T7, increasing with time. The ΔE value between the initial color at T0 and at T7, T30, T60, and T180 was significantly different for GMTA, WMTA, and TAP ( P < .001). ΔE values for the BD, RRM, RRMF, AH+, and NF groups were not statistically significantly different between T0 and T7, T30, T60, and T180, respectively, except for 3 samples below the human perceptible threshold. Values of L* dropped significantly from T0 to T180 in the TAP, GMTA, and WMTA groups. Conclusions Significant coronal tooth discoloration was caused by TAP, GMTA, and WMTA but not by BD, RRM, and RRMF. [ABSTRACT FROM AUTHOR]

Introduction Apical surgery is an important treatment option for teeth with post-treatment periodontitis. Although apical surgery involves root-end resection, no morphometric data are yet available about root-end resection and its impact on the root-to-crown ratio (RCR). The present study assessed the length of apicectomy and calculated the loss of root length and changes of RCR after apical surgery. Methods In a prospective clinical study, cone-beam computed tomography scans were taken preoperatively and postoperatively. From these images, the crown and root lengths of 61 roots (54 teeth in 47 patients) were measured before and after apical surgery. Data were collected relative to the cementoenamel junction (CEJ) as well as to the crestal bone level (CBL). One observer took all measurements twice (to calculate the intraobserver variability), and the means were used for further analysis. The following parameters were assessed for all treated teeth as well as for specific tooth groups: length of root-end resection and percentage change of root length, preoperative and postoperative RCRs, and percentage change of RCR after apical surgery. Results The mean length of root-end resection was 3.58 ± 1.43 mm (relative to the CBL). This amounted to a loss of 33.2% of clinical and 26% of anatomic root length. There was an overall significant difference between the tooth groups ( P < .05). There was also a statistically significant difference comparing mandibular and maxillary teeth ( P < .05), but not for incisors/canines versus premolars/molars ( P = .125). The mean preoperative and postoperative RCRs (relative to CEJ) were 1.83 and 1.35, respectively ( P < .001). With regard to the CBL reference, the mean preoperative and postoperative RCRs were 1.08 and 0.71 (CBL), respectively ( P < .001). The calculated changes of RCR after apical surgery were 24.8% relative to CEJ and 33.3% relative to CBL ( P < .001). Across the different tooth groups, the mean RCR was not significantly different ( P = .244 for CEJ and 0.114 for CBL). Conclusions This CBCT-based study demonstrated that the RCR is significantly changed after root-end resection in apical surgery irrespective of the clinical (CBL) or anatomic (CEJ) reference levels. The lowest, and thus clinically most critical, postoperative RCR was observed in maxillary incisors. Future clinical studies need to show the impact of resection length and RCR changes on the outcome of apical surgery. [ABSTRACT FROM AUTHOR]

Introduction The aim of this study was to evaluate the bond strength of various root canal sealers after various irrigation solutions and Er:YAG laser irradiation were used on root canal dentin. Methods One hundred fifty freshly extracted human maxillary single-rooted teeth were used in this study. Teeth were sectioned transversally 4 mm below the cementoenamel junction. The root canal of each specimen was prepared using a tapered bur. Teeth were divided into 3 main groups by sealer (AH Plus Jet [Dentsply DeTrey, Konstanz, Germany], EndoSequence BC Sealer [Brasseler, Savannah, GA], and Real Seal [SybronEndo, Orange, CA]) and then divided into 5 subgroups by dentin treatment (distilled water, calcium hydroxide, sodium hypochlorite, EDTA, and Er:YAG laser). The specimens were placed immediately at 37°C and 100% humidity for 1 week. Then, the push-out test was applied. The maximum failure load was recorded in newtons and was used to calculate the push-out bond strength in MPa. Then, 3 random specimens from each group were examined under scanning electron microscopy. Results The resin root canal sealers had higher push-out bond strength than the bioceramic sealer, and the differences were statistically significant ( P < .05) except in the sodium hypochlorite groups. The EDTA and Er:YAG laser applications removed the smear layer and increased the bond strength. The highest adhesion was observed in EDTA groups when each sealer was evaluated in itself. Conclusions The bonding strength of root canal sealers is influenced by their properties and various dentin surface treatments. The scanning electron microscopic study showed that although the dentinal tubules were open, at the profile examination the sealers did not penetrate into the dentin canals in all specimens. [ABSTRACT FROM AUTHOR]

Introduction The objective of the present study was to measure the orifice depth of middle mesial canals (MMCs) and evaluate the detectability of orifices using troughing preparation. Methods For this study, 85 mandibular molar teeth with MMCs were selected from the scanned micro–computed tomographic images. The MMCs were categorized, and the distances between the MMC orifices and the cementoenamel junctions (CEJ) were recorded as the depth of the orifice. Data were evaluated with frequency analysis and a chi-square test using SPSS (SPSS Inc, Chicago, IL), and the results indicated a 5% significance level. Results It was found that 77.41% of the MMC orifices were at the CEJ level, whereas 5.38% and 9.69% of the MMC orifices were detectable within 1-mm and 2-mm depths from the CEJ, respectively. Of the specimens, 7.52% had MMC orifices deeper than 2 mm from the CEJ. Confluent anatomy was the most frequent configuration. No significant relation was detected between the orifice depth and MMC configuration ( P > .05). Conclusions It was concluded that 77.41% of the specimens did not require troughing preparation, the remaining 15.07% would require troughing, and 7.52% could not be accessed even with the troughing preparation. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to describe the anatomy of mandibular premolars with type IX canal configuration by using micro–computed tomography. Methods: Mandibular premolars with radicular grooves (n = 105) were scanned, and 16 teeth with type IX configuration were selected. Number and location of canals, distances between anatomic landmarks, occurrence of apical delta, root canal fusion, and furcation canals, as well as 2-dimensional (area, perimeter, roundness, major and minor diameters) and 3-dimensional (volume, surface area, and structure model index) analysis were performed. Data were statistically compared by using analysis of variance and Kruskal-Wallis tests (α = 0.05). Results: Overall, specimens had 1 root with a main canal that divided into mesiobuccal, distobuccal, and lingual canals at the furcation level. Mean length of the teeth was 22.9 ± 2.06 mm, and the configuration of the pulp chamber was mostly triangle-shaped. Mean distances from the furcation to the apex and cementoenamel junction were 9.14 ± 2.07 and 5.59 ± 2.19 mm, respectively. Apical delta, root canal fusion, and furcation canals were present in 4, 5, and 10 specimens, respectively. No statistical differences were found in the 2-dimensional and 3-dimensional analyses between root canals (P > .05). Conclusions: Type IX configuration of the root canal system was found in 16 of 105 mandibular premolars with radicular grooves. Most of the specimens had a triangle-shaped pulp chamber. Within this anatomic configuration, complexities of the root canal systems such as the presence of furcation canals, fusion of canals, oval-shaped canals in the apical third, small orifices at the pulp chamber level, and apical delta were also observed. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The purpose of this study was to evaluate the fracture resistance after thermocycling of simulated immature teeth restored with composite, a fiber post, mineral trioxide aggregate (MTA), or gutta-percha. Methods: Eighty-four primary bovine mandibular incisors were divided into 7 groups (n = 12). Negative controls received no treatment. Teeth in all other groups were prepared to an internal diameter of 1.75 mm. After placement of 4-mm apical barrier of MTA, the canals were filled with their respective test materials to the facial cementoenamel junction. For the fiber post group, a fiber post was fitted to extend from the MTA barrier to 2 mm below the incisal edge and was cemented with Build-It FR. The positive controls were left unfilled. The access openings were filled with BisFil II composite. All teeth were then thermocycled for 500 cycles at 5°C and 55°C with a 30-second dwell time and 5-second transfer time. Each root was horizontally fractured through the test material by using an Instron Universal Testing Machine, and the peak load to fracture was recorded. The data were analyzed with analysis of variance and Tukey post hoc tests (P < .05). Results and Conclusions: Thermocycled composite was not significantly stronger than gutta-percha and MTA. The only material that significantly strengthened the simulated immature teeth was the fiber-reinforced composite with a fiber post. [Copyright &y& Elsevier]

Abstract: Introduction: Successful endodontic treatment is dependent on a perfect knowledge of normal root canal anatomy and variations from the norm. This study was aimed to investigate the root canal anatomy of mandibular first premolars by both radiography and cross-sectional methods in an Iranian population. Methods: Two hundred seventeen extracted human mandibular first premolars were used. Radiographs were taken in both mesiodistal and buccolingual directions for each premolar. Then, all the teeth were decoronated at the cementoenamel junction and resected perpendicular to their long axes into three equal sections and stained with fuscin. Digital photographs of the cross-sectional root surfaces were taken and surveyed at 40× magnification. The root canal configuration types were determined separately by radiographs and cross-sectional images for each premolar. Results: Out of 217 teeth examined, 192 (88.47%) had a single root canal. The remaining 25 teeth (11.53%) showed two canals in at least one cross-section of their roots with five root canal configurations. In the mesiodistal (MD) radiographs, only 5.99% of premolars showed two canals with three root canal configurations. Conclusions: One-hundred ninety two out of 217premolars showed one canal in both cross-section and MD radiography. Only 7 premolars were diagnosed as having more than one canal with the same canal configuration in both cross-sections and MD radiography methods. [Copyright &y& Elsevier]

Cell therapy in regenerative endodontics introduces an alternative option to classic treatment strategies for complex endodontic cases. The aim of this case report was to describe cell-based therapy using allogeneic umbilical cord mesenchymal stem cells (UC-MSCs) encapsulated in a bioscaffold for a complex case of a mature permanent tooth with apical periodontitis and accidental root perforation. A healthy 19-year-old man undergoing orthodontic treatment was referred for endodontic treatment in tooth #7; he was diagnosed with apical periodontitis during a previously initiated treatment associated with accidental perforation of the radicular cervical third. The root perforation was sealed with glass ionomer and composite resin, and the root canal was instrumented, disinfected, and dressed with calcium hydroxide. After 3 weeks, allogeneic UC-MSCs were encapsulated in platelet-poor plasma and then implanted into the root canal, and Biodentine (Septodont, Saint-Maur-des-Fosses, France) was placed below the cementoenamel junction. Finally, the tooth was restored with composite resin. Follow-up examinations were performed 6 months and 1 year later. The examinations included periapical radiography, cone-beam computed tomographic imaging, and sensitivity and vitality tests. Radiographic and cone-beam computed tomographic images indicated remission of the apical lesion. Clinical evaluations revealed normal responses to percussion and palpation tests; the tooth was responsive to the electric pulp test, and the vitality test indicated low blood perfusion units. This case report reveals the potential use of allogeneic cellular therapy using encapsulated UC-MSCS in a platelet-poor plasma scaffold for a complex case of a permanent tooth with apical periodontitis and root perforation. [ABSTRACT FROM AUTHOR]

This study evaluated and compared the shaping ability of the WaveOne Gold (Dentsply/Tulsa Dental Specialties, Tulsa, OK), TRUShape 3D Conforming File (Dentsply/Tulsa Dental Specialties), EdgeCoil (EdgeEndo, Albuquerque, NM), and XP-3D Shaper (Brasseler USA, Savannah, GA) endodontic file systems on oval-shaped canals using micro–computed tomographic (micro-CT) technology. Thirty-two oval-shaped, single-canal extracted human teeth were decoronated 1 mm coronal to the cementoenamel junction and scanned via a micro-CT scanner (μCT100; Scanco Medical, Bassersdorf, Switzerland). Teeth were divided into 4 groups (n = 8) and instrumented according to the manufacturer's instructions. Coregistered images, before and after root canal preparation, were evaluated for morphometric measurements of the surface area, volume, structure model index (SMI), conicity, and percent of walls untouched using the manufacturer's evaluation software (IPL Register, Scanco Medical). Data were statistically compared between groups using 1-way analysis of variance and within groups using a paired sample t test. Instrumentation with all file types increased the surface area, volume, and conicity between and within groups. There was no statistically significant difference between the groups for any of the rotary instruments used (P <.05). Instrumentation of oval-shaped canals with WaveOne Gold, TRUShape, EdgeCoil, and XP-3D Shaper rotary endodontic instruments similarly increase the volume, surface area, and conicity. None of the file systems were capable of contacting all of the surface area in any canal. [ABSTRACT FROM AUTHOR]