Influence of Cavity Designs on Fracture Resistance: Analysis of the Role of Different Access Techniques to the Endodontic Cavity in the Onset of Fractures: Narrative Review.

Objectives: In recent years, new endodontic access techniques have been proposed with the aim of preserving as much dental tissue as possible for subsequent prosthetic rehabilitation. It has indeed been demonstrated that the success of this therapy is essential and dependent on the proper execution of endodontic cavity access. The main objective is to provide a comprehensive and up-to-date overview of the new access techniques in endodontics in order to guide clinical practice toward a more precise and qualitative approach. As of today, there is still no universally standardized and recognized taxonomy for the different access cavity designs described in the literature. It has been observed that there are various nomenclatures in the literature. The cavity access designs described mainly in the literature can be categorized into six groups: Traditional Access Cavity (TradAC), Conservative Access Cavity (ConsAC), Ultra-Conservative Access Cavity (UltraAC), Truss Access Cavity (TrussAC), Caries-Guided Access Cavity (CariesAC), and Restoration-Guided Access Cavity (RestoAC). Materials and Methods: The drafting of this narrative review followed the indications of the SANRA (Scale for the Assessment of Narrative Review Articles). A search for scientific articles was conducted on the PubMed and SCOPUS databases, using the following search query: ((truss) OR (conservative) OR (ninja) OR (traditional)) AND access AND endodontic. Results: The initial search yielded a total of 941 articles. After removing duplicates using EndNote X8 software, the number of articles decreased to 785. By applying the inclusion and exclusion criteria, a total of 64 articles were obtained. Among these, 20 articles were finally selected for the purposes of this review, 11 literature reviews and 9 ex-vivo studies. Conclusion: Studies on fracture resistance have yielded heterogeneous results. For anterior teeth, studies do not find a significant relationship between different endodontic access cavities and fracture resistance. However, in the posterior sector, there is more discrepancy and many positive results for minimally invasive access cavities seem to relate to molars. Therefore, it can be concluded that the evidence supporting the influence of endodontic preparations on dental fracture resistance is still limited. Research on new endodontic access techniques holds significant clinical relevance in contemporary endodontics. The evolution of dental technologies, including cone beam computed tomography (CBCT) and computer-guided cavity preparation, has ushered in the era of minimally invasive endodontics. This shift aims to enhance the precision and quality of endodontic treatments while preserving maximum healthy dental tissue for subsequent prosthetic rehabilitation. The success of endodontic therapy is closely tied to the proper execution of access to the endodontium, influencing all phases of endodontic treatment and playing a role in determining fracture resistance for subsequent rehabilitation phases. The dichotomy between traditional and minimally invasive approaches has spurred clinical investigations. Specifically, within the scientific community, doubts have been raised about the potential limitations of minimally invasive access cavities. Concerns include their impact on canal orifice localization and raise questions about their influence on the overall success of endodontic treatment. This review holds clinical significance as it sheds light on the evolving landscape of endodontic access techniques, analyzing the anatomical trajectory, carefully examines the transition to minimally invasive approaches, and critically assesses existing scientific evidence and concerns surrounding these developments, contributing to an informed decision-making process in clinical practice.

Clinical outcome of non-surgical root canal treatment using different sealers and techniques of obturation in 237 patients: A retrospective study.

OBJECTIVES: The aim of this retrospective study was to compare the clinical results of two root canal sealers and three obturation techniques used for non-surgical root canal treatment. MATERIALS AND METHODS: A total of two hundred eighty-three root canal treated teeth in two hundred thirty-seven patients with minimum a 6-month follow-up was included for this study. The canals were filled with three different modes: 1) cold lateral condensation (CLC) and AH Plus Sealer; 2) continuous wave condensation technique (CWC) and AH Plus Sealer, and 3) sealer-based obturation technique (SBO) and AH Plus Bioceramic Sealer. The treatment outcome was analysed based on clinical signs and symptoms, and periapical radiograph (periapical index, PAI). RESULTS: There were no significant differences in treatment outcome between various sealers and filling techniques applied. The sealer extrusion was found most frequently in the CWC group (60.67%), followed by SBO (59.21%) and CLC (21.19%) with statistically significant differences (p < .05). The initial diagnosis, previous treatment and sealer extrusion (p < .05) were prognostic factors that affected treatment outcome. CONCLUSIONS: Based on the findings of this study, neither the sealer type nor the filling technique affected the treatment success while preoperative diagnosis, previous treatment and sealer extrusion had significant effect on the outcome. CLINICAL RELEVANCE: A bioceramic sealant applied along with the single-cone technique might be considered as an alternative method in root canal obturation.

Quality of Root Canal Fillings and Procedural Errors for In Vivo Studies Prepared in Different Clinical Settings and with Rotary Systems: A Systematic Review.

BACKGROUND This systematic review of the literature aimed to identify published studies and evaluate them on the quality of root canal fillings (RCF) and procedural errors with rotary systems for in vivo studies prepared for different clinical settings. MATERIAL AND METHODS A full literature exploration was conducted in Clarivate Analytics' Web of Science, Elsevier's Scopus, Embase, and PubMed for studies published between January 2020 and March 2024. A manual search was also performed by reviewing the references of selected papers. The following keywords were used: quality of root canal filling(s) OR quality of root canal obturation, root canal obturation OR endodontic treatment, clinical setting (academic, private, governmental), AND/OR procedural errors and rotary instrumentation. RESULTS Sixteen clinical studies were included in this review. The acceptance percentages for obturation length, density, and taper were 76.3%, 74.7%, and 82.5%, respectively, indicating significantly high, good ratios. The overall RCF recorded showed that 68.2% of root canal obturations were considered acceptable. Acceptable rates remained higher than unacceptable rates in academic, hospital, and private settings, and percentages ranged from 65.2% to 93.0%. Only 5 studies reported procedural errors, namely, ledge formation, separated instruments, apical perforation, transportation, lateral perforation, and root/foramen perforation. CONCLUSIONS Using rotary instruments for different root canal treatment steps as instrumentation and obturations is highly recommended. Among different clinical setting and practice, these instruments resulted in a good and acceptable RCF, overall quality performed by those instruments, and few procedural errors.

Nonsurgical management of large periapical lesions: case reports and review of the literature.

The objectives of this article are to report 2 cases of nonsurgical endodontic treatment for the management of periapical lesions associated with large cortical bone perforations and review the literature on the clinical efficacy of nonsurgical endodontic treatment to draw insights from published case reports. Large, cyst-like periapical lesions in 2 patients were successfully treated with combined modalities of root canal treatment, antimicrobial therapy (calcium hydroxide and triple antibiotic paste [TAP]), and mineral trioxide aggregate (MTA) obturation of the canal space. In both cases, instrumentation was extended 1 mm beyond the apical foramen to facilitate drainage through the root canal, because it was assumed that the periapical lesion could be cystic. After instrumentation, TAP was placed within the canal space to aid in disinfection and healing of the dental, pulpal, and periapical conditions. In both patients, the teeth were asymptomatic and functional at follow-up examinations (case 1, 3 years; case 2, 30 months). Supporting the positive outcomes in the 2 clinical cases, the published literature suggests that the use of biocompatible materials such as MTA, which can promote the deposition of hydroxyapatite, has the potential to contribute to tissue regeneration and the healing of large periapical lesions.

Endo-Perio Lesions and Dentists' Treatment Approach: A Survey.

BACKGROUND Endo-perio lesions are a great challenge for dentists. The aim of this study was to evaluate the treatment approach of dental practitioners to endo-perio lesions by considering the current endo-perio classification. MATERIAL AND METHODS An online survey was prepared, consisting of questions about the treatment approach to 3 simulated cases with endo-perio lesions, shown on periapical radiography. Details of the patient's age, presence of systemic disease, smoking, and how the single- or multi-rooted tooth would affect the treatment plan were also included in the simulated cases presented in the survey. The survey was sent to 1500 dentists via e-mail, WhatsApp, and social media platforms. The chi-square test was used for comparison of data. Significance was evaluated at P<0.05. RESULTS In total, 338 dentists participated in the survey, including general dentists, endodontists, and periodontists. Fifty-three percent of participants stated that they would perform root canal treatment and initial periodontal treatment simultaneously, when both treatments were required. In cases classified as grade 3, most general dentists, endodontists, and periodontists answered that they would prescribe systemic antibiotics if there was diffuse extra-oral swelling (P<0.05). Moreover, in grade 3 cases, more general dentists chose the option "extraction" as the best choice, compared with endodontists and periodontists, who did not choose extraction as often (P<0.05). CONCLUSIONS According to the results of this study, general dentists, endodontists, and periodontists generally follow different approaches to endo-perio lesions. A consensus is needed on this issue to develop a successful multidisciplinary approach to endo-perio lesions.

Comprehensive Analysis of Mandibular First Molar Root and Canal Morphology in Saudi Patients Using Cone Beam Computed Tomography (CBCT).

BACKGROUND The goal of conventional endodontic therapy is to clean the root canal system thoroughly, restore tooth function, and prevent re-infection. Success depends on understanding root canal morphology, resolving apical periodontitis, and using proper techniques. Studies highlight variations in root canal anatomy, with cone-beam computed tomography (CBCT) being crucial for accurate diagnosis despite its high cost and limited availability. MATERIAL AND METHODS This retrospective study reviewed CBCT images of 1820 (907 male, 913 female) patients aged 18 to 78 years. Analysis included 2081 mandibular first molars for variations in root and canal morphology and right- and left-side symmetry. Inter-orifice distance was measured, along with distance from the cementoenamel junction (CEJ) to the level of canal bifurcation. RESULTS In this study, 96.01% of teeth had 2 roots and 3.89% had 3 roots. The percentages of canal configuration were 77.70% for 3 canals, 21.58% for 4 canals, 0.67% for 2 canals, and 0.05% for 1 canal. The inter-orifice distance was 2.07 mm for 2 canals in 1 root and 2.86 mm for 2 canals in separate distal roots. Distance from the CEJ to canal bifurcation varied significantly between 2 canals within 1 distal root (3.35 mm), 2 canals in separate distal roots (1.60 mm), as well as between distal (3.35 mm) and mesial roots (1.10 mm). CONCLUSIONS In mandibular first molars, only 3.89% have additional distolingual roots. Sex and ethnicity showed no influence on number of roots and canals. Distal canals showed a deeper bifurcation and greater inter-orifice distance than did mesial canals.

Efficacy of preoperative and postoperative medications in reducing pain after non-surgical root canal treatment: an umbrella review.

OBJECTIVE: This study analyzed, using an umbrella review, existing systematic reviews on medications to prevent and control postoperative endodontic pain to guide professionals in choosing the most effective drug. MATERIALS AND METHODS: An electronic search in the PubMed (MEDLINE), LILACS, SciELO, EMBASE, Scopus, Web of Science, Cochrane Reviews, and Data Archiving and Networked Services (DANS) databases retrieved 17 systematic reviews. The study included only systematic reviews of clinical trials with or without meta-analyses evaluating effectiveness of medications in reducing pain after non-surgical endodontic treatment. RESULTS: The evidence showed that steroidal and non-steroidal anti-inflammatory drugs and opioids effectively controlled pain within six to 24 h. CONCLUSIONS: Dexamethasone, prednisolone, paracetamol, and mainly ibuprofen provided higher postoperative pain relief. The quality of evidence of the reviews ranged from very low to high, and the risk of bias from low to high, suggesting the need for well-designed clinical trials to provide confirmatory evidence. CLINICAL RELEVANCE: This review emphasizes the efficacy of developing protocols for pain control after endodontic therapy.

Comparison of selective laser melting and stereolithography etching templates for guided endodontics.

Background: With the increasing application of guided endodontics to treat complex root canal treatment, the entire process of root canal treatment has become more precise, reducing damage to tooth structure and improving success rates. However, due to the limitations of the operating space, the use of guided endodontic templates in posterior root canal treatment is less common. This study aims to compare the accuracy and reliability of selective laser melting (SLM) and traditional stereolithography etching (SLA) guided endodontic templates for posterior root canals, providing better treatment strategies for posterior root canal treatment. Methods: The teeth were randomly assigned to either SLM or SLA group. Preoperative cone-beam computed tomography (CBCT) and a three-dimensional (3D) scanner were used to establish the 3D root canal system and the accurate occlusal models of the teeth. The virtual access to the canal access was designed using Mimics 19.0 and 3-Matic 11.0. The endodontic access was performed based on either SLM or SLA templates. The accuracy of endodontic preparation was measured in three-dimensions by calculating deviations from planned accesses. The template height and tooth substance loss rates in each group were measured. Results: SLM-guided templates have a low average deviation at the entry point and apical portion of the bur of total posterior teeth (including premolars and molars) and individual molars (P < 0.05). Moreover, there was a significant difference in angular deviations and height of template in total posterior teeth and individual molars (P < 0.05). The mean substance loss rate of the SLA group was slightly greater than that of the SLM group, but the difference was not statistically (P > 0.05). Conclusions: SLM-guided endodontics provides a more predictable and precise location of root canal orifice for the treatment of posterior teeth.

The effect of educational animation compared to leaflets on patients' knowledge regarding root canal treatment: a randomized controlled trial.

BACKGROUND: Incorporating video as a tool for education offers a multitude of advantages. However, it is unknown what is the best educational tool to use for increasing public awareness, consequently reducing fear about root canal treatment. For this reason, this study aimed to compare the effectiveness of educational animation and leaflets as delivery methods for providing information on root canal treatment to patients and to assess their ability to retain the information. METHODS: One hundred fifty adult volunteers were recruited via social media and Umm Al-Qura University Dental Hospital to participate in this randomized control trial study. The volunteers were divided into the study group (SG) and the control group (CG). The SG was provided with information through animations created by the research team, while the CG received the same information through a leaflet. Pre-intervention (T1), immediate post-intervention (T2), and one-month post-intervention (T3) validated questionnaires were completed by the participants to assess the changes in their knowledge. To evaluate the impact of the information delivery method, the knowledge scores of T2 and T3 were compared to T1 within each group using Paired T-tests. Additionally, the study compared the knowledge scores of the two groups using unpaired T-tests. The significance level was set at a P-value of less than 0.05. RESULTS: A significant improvement in endodontic therapy knowledge among the participants in both groups (T1 compared to T2 in the same group) was noted (P < 0.050). However, when comparing T2 between groups, no significant difference was found in delivering the information and improving the knowledge (P = 0.080). Still, the mean differences between T1 and T2, as well as T1 and T3, were greater (P < 0.050) in the SG than in the CG. Furthermore, the total knowledge score in the SG at T3 was significantly higher than the CG. CONCLUSION: Both educational animation and leaflets are practical tools to increase patients' awareness about root canal treatment. However, educational videos are more effective than leaflets in delivering and retaining information about root canal treatment. TRIAL REGISTRATION: This study was retrospectively registered as a randomized control trial at the ISRCTN registry with the document number ISRCTN18413241, 15/05/2023.

A 12-month randomized controlled trial to assess the efficacy of revitalization of retreated mature incisors with periapical radiolucency in adolescents.

The use of regenrative endodontics is restoring the health status of the root canals of retreated mature teeth is a novel approach. Therefore, the current trial aimed to compare the effectiveness of regenerative endodontic procedures (REPs) to non-surgical root canal retreatment (NS-RCR) in reducing periapical radiolucency over one year for the retreatment of mature incisors with periapical periodontitis. The secondary purpose was to assess clinical success and regain pulp sensibility. A parallel randomized controlled trial, 66 mature incisors with periapical radiolucencies were randomly divided into two equal groups and retreated with either REPs or NS-RCR. At baseline and after 6 and 12 months, teeth were assessed clinically and radiographically using a periapical index (PAI). The Mann-Whitney test was used to analyze nonparametric PAI scores. The Electric pulp test readings were analyzed using the repeated measure analysis of variance (ANOVA). Over the follow-up intervals, there was no significant intergroup difference in the PAI medians, the majority of the teeth displayed a reduction in periapical radiolucency. At the end of the follow-up period, the clinical successes for the REP and NS-RCR groups were 93.9% and 97%, respectively (p = 0.555). Positive pulp sensibility was recorded in 54.54% of cases in the REPs after 12 months. Both approaches showed a comparable diminishing of periapical radiolucencies and equivalent clinical results. A conventional, non-surgical endodontic retreatment may not always be necessary.

Endodontic microsurgery and prosthodontic treatment of a permanent anterior concrescence: A case report.

Concrescence is a rare dental anomaly in which two adjacent teeth are united only by their cementum. Concrescence most frequently occurs in molars, especially a third mandibular molar and a supernumerary tooth. It is rarely seen in the maxillary anterior teeth. This case report is the first in the literature which details the successful treatment of a concrescence between the maxillary central incisor and a supernumerary tooth through multidisciplinary therapy. The treatment plan included root canal treatment, endodontic microsurgery, and prosthodontic treatment.

[Application of ultrasonic irrigation combined with chlorhexidine in root canal treatment of pulpitis].

PURPOSE: To explore the clinical effect of ultrasonic irrigation combined with chlorhexidine in root canal treatment of pulpitis. METHODS: A total of 120 patients with pulpitis treated with root canal therapy were randomly divided into a study group (n=60, 72 affected teeth) and a control group (n=60, 70 affected teeth). During root canal preparation, the study group was treated with chlorhexidine combined with ultrasonic irrigation, while the control group was treated with chlorhexidine conventional irrigation. The bacterial count and endotoxin content in the root canal before and after root canal preparation were compared between the two groups, as well as the endodontic inter-appointment pain (EIAP), lateral branch root canal filling rate, and degree of tooth pain after root canal treatment. The success rate of treatment was statistically analyzed after one-year follow-up. Statistical analysis was performed with SPSS 19.0 software package. RESULTS: After root canal preparation, the number of colonies in experimental group and control group was significantly decreased compared with that before root canal preparation(P＜0.05), and the number of colonies in experimental group was significantly lower than that in control group(P＜0.05). After root canal preparation, endotoxin levels in experimental group and control group were significantly lower than those before root canal preparation(P＜0.05), and the level in experimental group was significantly lower than that in control group(P＜0.05). The lateral branch root canal filling rate in the study group and the control group was 29.17% and 11.43%, respectively, with significant difference between the groups(P＜0.05). The incidence of EIAP was 4.17% and 14.29%, respectively, with significant difference between the two groups(P＜0.05). At 48 hours after surgery, the visual analogue score (VAS) of the study group and the control group was (2.74±0.61) and (3.29±0.68), respectively, which were significantly lower than at before surgery(P＜0.05). There was a significant difference in VAS score between the two groups 48 hours after surgery(P＜0.05). One week after surgery, the VAS score in the study group and the control group was (1.52±0.34) and (1.81±0.42), respectively, significantly lower than that before and 48 hours after surgery(P＜0.05). There was a significant difference in VAS score between the two groups at one week after surgery (P＜0.05). The successful rate of treatment in the control group was 84.62%, and 95.71% in the study group, with a significant difference between the two groups(P＜0.05). CONCLUSIONS: The application of ultrasonic irrigation combined with chlorhexidine in the treatment of pulpitis root canals can help reduce the level of bacteria and endotoxin after root canal preparation, alleviate the degree of postoperative tooth pain, and improve the filling rate of lateral branch root canals, with superior curative effects.

[Dental treatment under general anesthesia among pediatric patients in 120 consecutive cases: a retrospective study].

PURPOSE： To investigate the clinical features of children who received treatment under dental general anesthesia (DGA). METHODS: The clinical records of dental patients below 18 years old who were treated under DGA at the Department of Pediatric Dentistry, Affiliated Dental Hospital of Kunming Medical University during June 2017 to November 2019 were obtained, including the baseline information, causes for DGA, anesthesia methods, intubation methods, treatment items, treatment time and follow-up visits. SPSS 26.0 software package was used to analyze the data. RESULTS: A total of 120 patients were included, 58.3% were males, and children aged 3 to 6 years showed the highest demand for DGA (85.0%). Fear of dental treatment, ineffective non-drug behavior management was the main causes for DGA in young children, while the most common causes for children over 6 years old to choose DGA were mental retardation (38.9%) and patients' needs(38.9%). The average number of teeth treated was (15.16±3.42) for each child, and the average time for treating one tooth was 12.26 min. Restoration, root canal treatment and primary teeth pre-forming crown(including anterior preformed resin transparent crown and posterior preformed metal crown) were the main treatment items. At 1-week follow-up visits, 98.3% of children had no discomfort. During 2017 to 2019, there was an increasing tendency in the number of patients who chose DGA in the authors' institute. CONCLUSIONS： The dental issues of children with fear of dental treatment, ineffectiveor non-drug behavior management or mental retardation can be treated under DGA conveniently, safely and efficiently. The acceptance rate of DGA among pediatric patients is on the rise. DGA training programs and related support projects are needed to meet the treatment demands among patients in less developed areas.

Comparative evaluation of selected concentrations of sodium hypochlorite on the outcome of endodontic therapy among Ghanaians.

BACKGROUND: Endodontic treatment is one of the main dental treatments to manage inflamed or infected root canal systems of teeth. The success of endodontic treatment principally depends on eradicating microorganisms in the root canal by chemo-mechanical debridement with irrigation solutions like sodium hypochlorite (NaOCl). NaOCl has been used in concentrations ranging from 0.5% to 5.25%. This study determined the antimicrobial effectiveness of selected concentrations (0.5%, 1.0%, 2.6%, and 5.2%) of NaOCl in endodontic treatment. METHODS: The study sites were the University of Ghana Dental School (UGDS) and Noguchi Memorial Institute for Medical Research (NMIMR). Sixty infected single-rooted single-canal teeth were used. Before (S1) and after (S2), root canal samples during the endodontic treatment with the selected concentrations of NaOCl were examined via anaerobic and aerobic cultures. The isolates were identified using Matrix Assisted Laser Desorption Ionization-Time Of Flight Mass Spectrometry (MALDI-TOF MS). RESULTS: All S1 samples were positive for cultivable bacteria. Fifty-three (53) different microbial species belonging to 20 different microbial genera were isolated. Streptococcus viridans was the most frequently isolated microbe. There were zero isolates in the root canals irrigated with 2.6% and 5.2% NaOCl. Two teeth had isolates in the groups irrigated with the lower concentrations (0.5% and 1.0%) of NaOCl. The persistent bacteria were one species each of Streptococcus mitis and Streptococcus oralis, respectively. CONCLUSION: Root canal treatments using chemo-mechanical preparation with the selected concentrations (0.5%, 1.0%, 2.6%, and 5.2%) of NaOCl were effective in significantly reducing the microbial load, and for the 5.2% and 2.6% concentrations, in eliminating all the microorganisms.

Effect of Dental Implant System-Assisted Tooth Intentional Replantation in the Treatment of Anterior Teeth with Pathological Tooth Flaring, Drifting and Elongation in Patients with Stage III/IV Periodontitis: a Case Series.

OBJECTIVE: To investigate the clinical effect of implant-assisted dental intentional replantation (IR) for the treatment of "drifted" anterior periodontally hopeless teeth (PHT). METHODS: The present authors recruited 22 patients with stage III/IV periodontitis who suffered drifting of the maxillary anterior teeth, with a total of 25 teeth. The PHT were extracted for in vitro root canal treatment (RCT). The root surface was smoothed and the shape was trimmed, and the alveolar socket was scratched. The dental implant system was used to prepare the alveolar socket according to the direction, depth and shape of the tooth implantation. The PHT were reimplanted into the prepared alveolar socket. The periodontal indicators were analysed statistically before and after surgery. RESULT: Twenty-two patients who completed the full course of treatment, with a total of 25 PHT, had a successful retention rate of 88%. Mean periodontal probing depth (PPD) decreased by 2.880 ± 0.556 mm and 3.390 ± 0.634 mm at 6 months and 1 year, respectively, and clinical attachment loss (CAL) decreased by 2.600 ± 0.622 mm and 2.959 ± 0.731 mm at the same time points, respectively, showing significant improvement (P < 0.05). CONCLUSION: Dental implant system-assisted IR can effectively preserve "drifted" natural PHT in patients with stage III/IV periodontitis.

Accuracy evaluation of dental CBCT and scanned model registration method based on pulp horn mapping surface: an in vitro proof-of-concept.

BACKGROUND AND AIM: 3D fusion model of cone-beam computed tomography (CBCT) and oral scanned data can be used for the accurate design of root canal access and guide plates in root canal therapy (RCT). However, the pose accuracy of the dental pulp and crown in data registration has not been investigated, which affects the precise implementation of clinical planning goals. We aimed to establish a novel registration method based on pulp horn mapping surface (PHMSR), to evaluate the accuracy of PHMSR versus traditional methods for crown-pulp registration of CBCT and oral scan data. MATERIALS AND METHODS: This vitro study collected 8 groups of oral scanned and CBCT data in which the left mandibular teeth were not missing, No. 35 and No. 36 teeth were selected as the target teeth. The CBCT and scanned model were processed to generate equivalent point clouds. For the PHMSR method, the similarity between the feature directions of the pulp horn and the surface normal vectors of the crown were used to determine the mapping points in the CBCT point cloud that have a great influence on the pulp pose. The small surface with adjustable parameters is reconstructed near the mapping point of the crown, and the new matching point pairs between the point and the mapping surface are searched. The sparse iterative closest point (ICP) algorithm is used to solve the new matching point pairs. Then, in the C + + programming environment with a point cloud library (PCL), the PHMSR, the traditional sparse ICP, ICP, and coherent point drift (CPD) algorithms are used to register the point clouds under two different initial deviations. The root square mean error (RSME) of the crown, crown-pulp orientation deviation (CPOD), and position deviation (CPPD) were calculated to evaluate the registration accuracy. The significance between the groups was tested by a two-tailed paired t-test (p < 0.05). RESULTS: The crown RSME values of the sparse ICP method (0.257), the ICP method (0.217), and the CPD method (0.209) were not significantly different from the PHMSR method (0.250). The CPOD and CPPD values of the sparse ICP method (4.089 and 0.133), the ICP method (1.787 and 0.700), and the CPD method (1.665 and 0.718) than for the PHMSR method, which suggests that the accuracy of crown-pulp registration is higher with the PHMSR method. CONCLUSION: Compared with the traditional method, the PHMSR method has a smaller crown-pulp registration accuracy and a clinically acceptable deviation range, these results support the use of PHMSR method instead of the traditional method for clinical planning of root canal therapy.