Stress distribution and axial force under different filing parameters during root canal preparation: An in vitro FEA and experimental study.

Clinical relevance of the new classification for mastoid progression in the staging and classification criteria for middle ear cholesteatoma proposed by the Japan Otological society.

A BSTRACT Introduction: QMix is a newer formulation known to be a more effective irrigant. A polypropylene canal brush facilitates the introduction of surfactant in the canal. Objective: To assess the efficacy of QMix with canal brush to eliminate smear layer and debris in a root canal that is instrumented with ProTaper Next and WaveOne files under scanning electron microscope. Methods: Forty single-rooted premolars were allocated into four groups:1) ProTaper Next file, 2) ProTaper Next file + Rotary Canal Brush, 3) WaveOne file, 4) WaveOne file + Rotary Canal Brush. All files were used up to size 40 in their respective tapering. For irrigation, sodium hypochlorite (5.25%) was used throughout instrumentation and QMix was used after instrumentation. The rotary canal brush in assigned groups was used for 30 sec along with QMix, followed by irrigation with 5ml distilled water. The roots were sectioned into two halves and analyzed under SEM. Results: The mean scores for debris and smear layer were lesser in WaveOne and WaveOne with canal brush groups compared to other groups Conclusion: The use of canal brush created cleaner canal walls than without canal brush. The most superior results were delivered by WaveOne rotary file.

Background: Rehabilitation of the severely atrophic posterior mandible remains surgically challenging, and inferior alveolar nerve (IAN) repositioning is a well-established technique that enables implant placement in anatomically compromised cases. Although neurosensory outcomes following nerve relocation have been extensively investigated, the regenerative capacity of the mandibular canal itself has not been previously evaluated. This study presents the first computer-assisted, cone-beam computed tomography (CBCT)-based assessment of bony canal regeneration after IAN transposition. Methods: Twenty-two patients who underwent unilateral IAN transposition were evaluated using standardized CBCT one year postoperatively. A semi-manual segmentation workflow was performed using Mimics Core Medical software version 27.0 (Materialise), and regenerated canal walls were identified according to four strict criteria: (1) canal continuity across sequential CBCT sections, (2) defined canal walls demonstrating high-density bone (>800 HU, or >400 HU), (3) ≥270° circumferential bony enclosure, and (4) morphology consistent with the native mandibular canal. Regeneration was quantified as the proportion of the surgically disrupted canal segment exhibiting a fully, or near fully, reconstructed canal. Results: Mandibular canal regeneration was observed in all patients. The mean regeneration at one year was 72.7% ± 13% when applying strict >800 HU criteria, with 20 patients demonstrating substantial (>70%) reformation and 2 patients showing partial regeneration (<40%). When a lower density threshold (>400 HU) was applied to include early or less mineralized bone, the mean regeneration increased to 78.1% ± 11%, indicating the presence of maturing bone structures that did not yet meet full-density criteria. Conclusions: Computer-assisted CBCT analysis demonstrates that partial to extensive regeneration of the mandibular canal occurs within one year following IAN transposition. This study provides the first quantitative evidence of this phenomenon, highlighting the intrinsic regenerative potential of the mandibular canal and suggesting a possible association with postoperative neurosensory recovery.

To evaluate the shaping ability, debris removal efficiency and morphological alterations induced by the SAF Infinitum system during progressive instrumentation of flat-shaped root canals of mandibular incisors. Twelve extracted mandibular incisors with flat-shaped canals were selected using micro-CT and instrumented with 1.5-mm Self-Adjusting File (SAF) Infinitum instruments under continuous NaOCl-HEDP irrigation for 2, 4 and 6 min. Micro-CT scans were performed before and after each step to evaluate changes in canal volume, surface area, debris removal, unprepared canal walls and dentine thickness. Following the preparation procedures, all instruments were examined under a microscope for defects.Data were analysed using GLM for repeated measures and the Related-Samples Friedman test (α = 0.05). Root canal preparation with the SAF Infinitum significantly increased canal volume and surface area (p = 0.000), while progressively reducing unprepared canal wall areas and hard tissue debris (p = 0.000). Unprepared surfaces decreased by 77.8% and debris volume by 77.2% from 2 to 6 min, with improved cleaning efficiency over time. Dentine thickness also declined significantly (p < 0.001), particularly on the lingual surface at the pericervical area and the mesial surface at midroot. Buccolingual walls consistently remained above 1.0 mm, whereas only two mesiodistal cross-sections at the midroot level exhibited dentine thickness below 0.5 mm. After 6 min, all instruments showed structural deformations, and one specimen exhibited a minor intracanal fragment. This is the first study to evaluate the progressive, time-dependent effects of the SAF Infinitum system in challenging flat-shaped root canals. The system exhibited a time-dependent shaping effect, with most morphological changes occurring within the first 2 min, followed by continued, although more gradual, improvements up to 6 min. Cleaning efficacy increased steadily over time, while remaining dentine thickness generally stayed above critical safety thresholds. All instruments showed structural deformations after 6-min preparation.

Abstract Background The surgical management of cholesteatoma presents a classic dilemma between canal wall down (CWD) mastoidectomy, which offers low recurrence at the cost of anatomical and functional integrity, and canal wall up (CWU) mastoidectomy, which preserves hearing but has a historically higher recurrence rate. The introduction of the endoscope may mitigate the risks of CWU surgery by improving visualization of hidden recesses. This investigation aims to compare the recurrence rates and hearing outcomes of endoscopic-assisted canal wall up (EACWU) versus CWD tympanomastoidectomy. Methods This prospective, randomized clinical trial included 50 adult cases with cholesteatoma. Cases were randomly allocated to 2 groups: Group A (25 cases) underwent EACWU tympanomastoidectomy, and Group B (25 cases) underwent CWD tympanomastoidectomy. Preoperative assessment for all cases included otoscopic/endoscopic examination, CT of the petrous region, and pure-tone audiometry (PTA). The primary outcomes were disease recurrence, assessed via clinical and endoscopic follow-up, and hearing outcome, measured by changes in the air-bone gap (ABG) and air conduction (AC) thresholds at the 8th week postoperatively. Results Recurrence occurred in 8% of cases in the EACWU group compared with 4% in the CWD group, a difference that was not statistically significant ( p = 0.55). The EACWU group demonstrated a substantial postoperative hearing improvement, with the mean ABG decreasing from 34.80 dB to 18.08 dB (a mean closure of 16.72 dB, p &lt; 0.0001). Conversely, the CWD group experienced a significant hearing decline, with the mean ABG increasing from 32.40 dB to 42.00 dB ( p &lt; 0.0001). Postoperative ABG and AC thresholds were markedly better in the EACWU group relative to the CWD group ( p &lt; 0.0001 for both). Conclusion Endoscopic-assisted CWU tympanomastoidectomy offers a superior hearing outcome compared to CWD mastoidectomy, with a comparably low rate of disease recurrence. This evidence supports the use of EACWU as a primary surgical option for suitable cases with cholesteatoma to achieve both disease eradication and functional preservation.

Objective: To evaluate the accuracy and efficiency of an autonomous dental robotic system in performing calcified canal localization and negotiation on standardized three-dimensional (3D)-printed jaw models. Methods: Two pairs of standardized 3D-printed maxillary and mandibular models, containing a total of 56 teeth, 92 calcified root canals, were used. Virtual access paths were planned based on preoperative cone beam CT (CBCT) and intraoral scan data using digital dental design software. An experienced operator controlled the autonomous dental robotic system to perform canal localization, and drilling time were recorded. Postoperative CBCT images were registered with preoperative plans to calculate accuracy parameters, including coronal deviation, apical deviation, and angular deviation. The residual thickness of canal wall at drilling end level, and the success rate of calcified canal location was recorded as well. Multiple linear regression analysis was performed to evaluate the effects of tooth position, jaw position, operation side and calcification depth on accuracy and drilling time. Results: The coronal deviation, apical deviation, and angular deviation of the calcified canal negotiation assisted by the autonomous dental robot were 0.35 (0.21) mm, 0.47 (0.27) mm, and 1.17° (1.35°), respectively, with an average drilling time of 39.00 (25.25) s. The residual dentine thickness of canal wall at drilling end level was (1.24±0.51) mm. The success rate of calcified canal location was 95.7% (88/92). Multiple linear regression analysis revealed that jaw position had a significant effect on coronal deviation (P<0.05), while tooth position, operation only side, and calcification depth showed no significant influence on any accuracy parameters (P>0.05). Moreover, calcification depth had a significant effect on drilling time (P<0.05), whereas tooth position, jaw position, and operation side showed no significant influence (P>0.05). Conclusions: The autonomous dental robotic system demonstrated high accuracy and efficiency in calcified canal localization in vitro.

To determine whether transcanal surgery without mastoidectomy, canal wall up (CWU), canal wall down (CWD), or CWU mastoid obliteration (MO) surgery for pediatric cholesteatoma has a more favorable effect on middle ear pressure (MEP) homeostasis. Data from children having mastoid surgery for acquired cholesteatoma were collected prospectively. Tympanometric values of MEP were compared after transcanal, CWU, CWD, and MO surgery analyzing (i) a single measure per ear from last clinic visit, and (ii) linear mixed-effects modeling (LMEM) to control for multiple measures, surgeries, age, and cholesteatoma severity (EAONO-JOS stage). 742 surgeries on 471 ears and 2382 tympanograms were completed. At last visit, (average age 15.6 years [6.0-19.3]), Type a tympanograms were present in 80/173 (46%) of transcanal surgeries, 64/132 (48%) CWU, 15/32 (47%) CWD, and 11/25 (44%) MO (Chi-square, p = 0.19), but 185/209 (89%) contralateral ears without cholesteatoma (Chi-square: p = 1.08 × 10-7). Median MEP was -47 daPa (IQR: 133) after transcanal, -65 daPa (IQR: 156) after CWU, -90 daPa (IQR: 151) after CWD, and -31 daPa (IQR: 151) after MO surgery and (Kruskal-Wallis: p = 0.4) but 5 daPa (IQR: 45) in normal contralateral ears (Wilcoxon: p = 7.92 × 10-13). LMEM showed MEP was dependent on age (p = 6.3 × 10-7) but not type of mastoid surgery (p = 0.70) or EAONO-JOS stage (p = 0.51). MEP after surgery for pediatric cholesteatoma is similar after transcanal, CWU, CWD, or MO surgery and remains lower than normal. Hypotheses that propose beneficial effects of these different surgical approaches on MEP homeostasis are not supported, so should not be used to influence choice of surgical approach.

Many nickel-titanium (NiTi) rotary instruments are recommended for single use, yet they are often reused for economic reasons. This study aimed to evaluate how repeated use affects the cyclic fatigue resistance and root canal wall cleanliness of the Micro-Mega Remover file. A total of 40 new Remover files were divided into four groups based on the number of uses: Control Group (unused), Group I (1 use), Group II (2 uses), and Group III (3 uses), with 10 files in each group. Sixty extracted mandibular molars with curved canals were obturated using the single-cone technique and then randomly allocated to the experimental groups in accordance with the designated usage frequency (10 teeth for 1 use, 20 teeth for 2 uses, and 30 teeth for 3 uses). Following the retreatment procedures, all files-both from the control and experimental groups-were subjected to cyclic fatigue testing using a stainless-steel artificial canal with a 60° curvature and a 5mm radius. The time to fracture (in seconds) was recorded, and the number of cycles to fracture (NCF) was calculated. The fractured fragment lengths (in mm) were measured, and selected samples were examined under a scanning electron microscope (SEM). Additionally, micro-computed tomography (µCT) analysis was performed to assess the volume of residual canal filling material remaining on the root canal walls after the retreatment procedure. Statistical analysis was performed using the Kruskal-Wallis and Dunn tests (p < 0.05). Fracture time and NCF differed significantly among the groups (p < 0.001). Group I exhibited significantly higher values than Groups II and III, while the control group also performed better than Group III (p < 0.001). No significant differences were observed between the control group and Groups I or II, nor between Groups II and III. Fragment lengths were significantly shorter in Group I compared to Groups II and III (p < 0.001). µCT analysis revealed no significant differences in residual filling volume among the groups. SEM observations demonstrated fracture initiation lines, rough surfaces, and voids consistent with cyclic fatigue. In this in vitro study, the cyclic fatigue resistance of Remover files was found to be similar to the control group after the first and second uses; however, a significant decrease was observed from the first to the second use. Nevertheless, the third use showed lower resistance compared to the control group and was associated with an increased risk of fracture. In addition, µCT analysis revealed residual filling material remaining on the root canal walls in all groups, with no significant differences among them.

AIM of this in vitro study was to compare apical foraminal deformation at 3 mm from the tomographic apex after instrumentation of mesial canals of mandibular molars using two rotary systems: Endogal Rotary and VDW Rotate. MATERIALS AND METHODS. Thirty extracted mandibular molars were used and embedded in silicone impression material to facilitate tomographic analysis. The samples were randomly divided into two groups ( n = 15): Group A was instrumented with the Endogal Rotary system, and Group B with the VDW Rotate system. All teeth were scanned using tomography before and after instrumentation. Measurements were taken at 3 mm from the apex in axial sections using NNT Viewer software. The distances between canal walls and intercanal space were measured. Statistical analysis was performed using independent t-tests with a significance level set at 5%. RESULTS. No statistically significant differences were observed between the two groups for any of the evaluated parameters. Both rotary systems preserved the anatomy of the root canals and prevented excessive dentin removal in the apical third. CONCLUSIONS. The Endogal Rotary and VDW Rotate systems demonstrated similar performance in maintaining apical anatomy and minimizing foraminal deformation at 3 mm from the apex. Both systems are suitable for shaping mesial canals in mandibular molars with minimal structural compromise.

Nowadays apical periodontitis is considered to be a protective reaction of the body to the tooth pulp destruction and the root canal infection. Any pathogen infecting the root canal has the potential to cause periapical changes. The evolution of techniques for periodontitis treatment is closely related to the improvement of the methods of selecting irrigation solutions and mechanical tools aimed at qualitative preparation of the root canal for the complete elimination of the pathogenic root canal biofilm. Periodontitis is a common disease in the world today. The results of a meta-analysis (by C.S. Tiburcio-Machado, C. Michelon), conducted on the basis of the largest scientific evidence bases in 2019, confirmed the high prevalence of apical periodontitis among the adult population constituting 52 %. The prevalence of apical periodontitis varies as a rule depending on the age group. For example, it constitutes 33 % at the age of 20-30, 40 % at the age of 30-40, 48 % at the age of 40-50, 57 % at the age of 50-60 and 62 % in individuals over 60. According to numerous studies, the root canal cleaning cannot be done qualitatively using an instrumental method only. Almost one-third of the root canal surface cannot be treated with instruments, regardless of the chosen treatment approach. A smear layer is always left in the course of dentin mechanical processing. It is present in the infected root canal and includes microorganisms. The research included 13 microorganisms able to cause periodontitis and 10 irrigation solutions able to eliminate the pathogenic effect on the root canal biofilm. Different concentrations of sodium hypochlorite (5.25%, 5.25+ extra %, 6 %), Maleic acid 6 %, EDTA 17 %, Citric acid 40 %, Chlorhexidine 2 % were used. Sodium hypochlorite has a wide spectrum of antimicrobial action and eliminates spore bacteria, fungi, protozoa and viruses. Most organisms are neutralized upon contact with sodium hypochlorite of various concentrations. A smear layer is also important in the process of root canal treatment. It contains organic and inorganic components that are retained on the walls of the root canal and contain the remains of microorganisms and pulp. Maleic acid is a soft organic acid that has the property of removing the lubricated layer and intertubular dentin demineralization. EDTA is also able to remove the mineral component, soften the tissues and help to clean the openings of the dentinal tubules. The conducted microbiological studies showed a diverse effect of irrigation solutions on groups of different microorganisms causing periodontitis. The obtained results provide an opportunity to select differentially irrigation solutions for the elimination of microorganisms detected in the root canals. A positive result of the elimination of irrigation solutions on microorganisms causing periodontitis is observed. The prevalence of periodontitis among the population increases every day. Risk factors such as primary root canal treatment, repeated examination of root canals, incorrect solutions and mechanical instruments increase the frequency of periapical pathologies. Correctly chosen treatment approach and proper selection of irrigation solutions will help an endodontist to eliminate the pathogenic biofilm of the root canal, thereby reducing the probable periodontitis occurrence in the treated root canals in the future.

This study systematically reviewed the effect of photon induced Photo-Acoustic Streaming (PIPS), compared to Conventional Syringe Irrigation (CSI), on the removal of smear layer and/or debris from root canals. Searches and screening were conducted by two independent reviewers in PubMed/MEDLINE and EMBASE up to August 2025. Eligible studies were in vitro investigations on extracted human teeth evaluating smear layer and/or debris removal using Scanning Electron Microscopy (SEM). A descriptive analysis was performed, and the quality of the studies was assessed by an adapted version of the Joanna Briggs Institute (JBI) checklist. Of 911 screened studies, 14 met the inclusion criteria. PIPS generally showed superior smear layer removal compared with CSI. One study attributed the effect to 20% EDTA rather than the activation technique. Regardless of the irrigant used (distilled water, saline, NaOCl or EDTA), PIPS enhanced smear layer reduction. Removal was more effective in the cervical and middle root thirds than in the apical third. Risk of bias assessment classified 9 articles as medium, 4 as high and 1 as low risk. PIPS appears more effective than CSI in reducing smear layer on root canal walls and can be considered an alternative irrigant activation method. However, heterogeneity among studies limits direct comparisons, highlighting the need for standardized experimental protocols to clarify the effectiveness of PIPS and other techniques. Enhancing smear layer and/or debris removal is critical for disinfection and sealing in endodontics. PIPS shows potential to improve root canal cleanliness compared with CSI.

This study aimed to evaluate untouched canal areas, canal transportation, and centering ability of WaveOne Gold, R-Motion, and Reciproc Blue systems with different apical sizes and tapers using micro-computed tomographic (micro-CT) analysis.Thirty mesial roots of mandibular molars with single curvature were selected and assigned to three groups (n = 10): WaveOne Gold (25/.07v and 35/.06v), R-Motion (25/.06 and 40/.04), and Reciproc Blue (25/.08v and 40/.06v). All canals were prepared in two sequential stages with small and then larger instruments of the same system. Micro-CT scans were performed before, between, and after instrumentation. Reconstructed images (NRecon v.1.6.10, Bruker) were used to assess untouched canal walls, canal transportation, and centering ratio at 3, 5, and 7 mm from the apex.Shapiro-Wilk test was used for normality. One-way ANOVA with Tukey's post hoc test and paired t-tests were applied (α = 5%).Preoperative canal volume and surface area showed no significant differences among groups (p > 0.05). All systems demonstrated similar shaping performance regarding untouched areas, transportation, and centering ability in both preparation stages (p > 0.05). A significant reduction in untouched canal walls was observed after the second preparation stage in all groups (p < 0.05).Despite similar shaping outcomes among systems, the second preparation stage significantly reduced untouched canal walls, supporting its potential role in improving root canal cleaning efficacy.

IntroductionChronic otitis media with cholesteatoma (COMC) is a progressive and potentially destructive middle ear disease, with surgery as the treatment of choice. Its auditory, emotional, and social consequences significantly affect patients’ quality of life. The Chronic Otitis Media Questionnaire-12, Mexican version (COMQ-12-Mx), allows a validated assessment of this impact in the Mexican population.ObjectiveThe main objective of this study is to evaluate the effect of surgical treatment on quality of life and auditory function in patients with COMC, using the COMQ-12-Mx.Material and methodsA prospective cohort study was conducted at the University Center of Otolaryngology and Head and Neck Surgery, “Dr. José Eleuterio González” University Hospital, Monterrey, Mexico, from May to October 2025. Twenty-five adults with clinically and radiologically confirmed COMC were included. The COMQ-12-Mx and audiometric tests were applied before and three months after surgery.ResultsTwenty-five affected ears were analyzed (median age 47 years; 56% female). The most frequent comorbidities were type 2 diabetes (32%), bilateral chronic otitis media (28%), and hypertension (16%). Main symptoms included tinnitus (68%), otalgia (64%), and otorrhea (64%). The attic-antral region was most commonly involved (68%). Simple mastoidectomy (76%) and type III tympanoplasty (78.6%) were the predominant techniques. Postoperative complications occurred in 24%, mainly graft perforation (16%). The pure-tone average (PTA) showed a trend toward improvement (48 dB preoperative vs 42 dB postoperative; p = 0.059). Total COMQ-12-Mx scores significantly decreased (29 vs 21; p < 0.001), with improvement across all subdomains and a large effect size (r = 0.87). Both canal wall up (CWU) and endoscopic techniques improved global scores, while only CWU showed significant PTA improvement (p = 0.041).ConclusionsSurgery for COMC was associated with within-group improvement in quality of life, particularly in symptoms and emotional impact. The COMQ-12-Mx adequately detected postoperative changes and served as a reliable tool to assess clinical and functional outcomes after surgical treatment.

This study compared conventional needle irrigation (CNI), shock wave-enhanced emission photoacoustic streaming (SWEEPS), EDDY sonic-powered irrigation, and the XP-endo Finisher for organic tissue removal in simulated internal root resorption (IRR) cavities using 2.5% and 5% NaOCl. One hundred and twenty single-rooted mandibular first premolars were instrumented, split longitudinally, and standardized semicircular IRR cavities were prepared in the canal walls. Bovine muscle tissue samples were weighed and adapted into the cavities. The reassembled root segments were divided into three irrigant groups (distilled water, 2.5% NaOCl, or 5% NaOCl) and four activation subgroups (CNI, SWEEPS, EDDY, and XP-endo Finisher) (n = 10 per group). A total of 7 mL of irrigant (3 mL NaOCl + 1 mL EDTA + 3 mL NaOCl) was applied with a total activation time of 2min, the roots were disassembled, and tissue dissolution was assessed by calculating the difference between the initial and final tissue weights. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni Correction. Under laboratory conditions, the use of SWEEPS and XP-endo Finisher with 2.5% and 5% NaOCl resulted in higher tissue weight loss compared to CNI and EDDY (p < 0.001), with no significant difference between them (p > 0.05). No significant difference was observed between 2.5% and 5% NaOCl, with or without activation methods (p > 0.05). Complete removal of organic tissue could not be achieved with any of the techniques. SWEEPS technology and XP-endo Finisher demonstrated higher efficiency in removing organic tissue from IRR cavities compared with the CNI and EDDY systems.

Laser treatment of natural canals is typical for phlebology, gynecology and urology. This method has several problems, including the choice of light dosimetry and instrumentation. It is important to provide a reliable and uniform energy distribution on the canal walls. Aimed at this, a sapphire tip is proposed in this work. Manufactured by the crystal growth technique, this tip has miniature dimensions and an axial cavity, which serves as a reflecting element. It can be combined with standard optical fibers providing contact coagulation. In this work, the performance of this instrument was studied numerically and experimentally, using exvivo liver samples. The results reveal an ability of the tip to form local coagulation without a sharp increase in temperature on the instrument surface. Thus, the sapphire tip demonstrates significant prospects for interstitial laser treatment, combining simple design, high reliability, reproducibility of the light distribution, and a smoothed thermal profile.

Among the various materials used for harvesting in tympanoplasty, the temporal fascia is a commonly-used material due to its accessibility and size. Surgeons can choose to use either the superficial or deep temporal fascia, or both. This study aimed to investigate the influence of the method used to harvest the temporal fascia on postoperative pain experienced by patients. The medical records of 89 patients who underwent canal wall up mastoidectomy with tympanoplasty and ossiculoplasty, performed by a single surgeon between 2021 and 2024, were retrospectively reviewed. In group A, the superficial temporal fascia is harvested. In group B, both the superficial and deep temporal fasciae are harvested together, resulting exposed temporal muscle. In group C, only the deep temporal fascia is harvested and the exposed temporal muscle is sealed by suturing the superficial temporal fascia. Postoperative pain was measured using the visual analog scale (VAS) in 3 groups on postoperative days 1, 3, and 14. The baseline characteristics are not significantly different in the 3 groups. VAS scores on postoperative days 1 and 3 showed a significant difference in 3 groups. Group B, which was supposed to have undergone most resection, exhibited the highest VAS scores, followed by group C and group A. The VAS scores on postoperative day 14 showed no difference among the 3 groups. Resection of the superficial temporal fascia is thought to be important for postoperative pain due to its rich innervation. Postoperative pain and the properties of the superficial and deep temporal fasciae can be taken into account when otologic surgeons select a harvesting method.

Is Non-Sac Contained Matrix a Major Predictor for Residual Disease in Acquired Cholesteatoma?

Background/Objectives: Diode lasers are used as adjuncts for endodontic disinfection, but their depth-resolved effects on root dentin are insufficiently described. This ex vivo study used optical coherence tomography (OCT) to qualitatively document laser-related morphological signatures on canal walls. Methods: Palatal roots from extracted maxillary first molars were standardized and hemisectioned to create specimens allocated to a conventional diode-laser protocol, a higher-power protocol, or control. A 940-nm diode laser with endodontic tips was applied per group. Swept-source OCT acquired serial B-scans along the root length. Two endodontists reviewed images for thermally induced morphological alterations (TIMAs). Reporting is descriptive. Results: OCT revealed laser-related hyper-reflective linear/radial signatures extending from the canal lumen toward the external root surface in laser-treated specimens. Qualitatively, signatures appeared more conspicuous and extended deeper with the higher-power protocol than with the conventional protocol. Findings were most evident in the coronal/middle thirds. Control specimens served to contextualize background appearances from preparation and sectioning. Representative B-scans illustrate typical patterns. The novelty of the present study results from the identification of areas of morphological alteration through the OCT examination of the walls of the root canals. Conclusions: Depth-resolved OCT can visualize dentinal alterations associated with diode-laser irradiation in an ex vivo model. These observations support careful parameter selection and motivate in situ studies with concurrent temperature monitoring and histologic correlation.

Total ossicular chain reconstruction may be performed using autologous cartilage or bone, or with a total ossicular replacement prosthesis (TORP). It is unclear if one method offers better hearing outcomes. The goal of this study was to compare hearing outcomes following total ossicular chain reconstruction with autologous material or TORPs. A single-institution prospective database was queried to identify patients who underwent total ossicular chain reconstruction and had available audiometric tests. Preoperative and postoperative air-bone gaps (ABG) at 0.5 to 4kHz were compared between patients who underwent total ossicular chain reconstruction with autologous material (cartilage or bone) or a TORP. Univariate and multivariate analyses were used to assess the impact of revision surgery, canal wall down surgery, cholesteatoma, mucosal pathology, and pneumatization on postoperative outcomes. One hundred and twenty-three patients underwent 134 surgeries for total ossicular chain reconstruction. The improvement in ABG was better in the TORP group compared with those who received autologous grafts (P<0.001; ΔABG 95% CI: -11.6 to -5.6dB). Cholesteatoma (P=0.01; 95% CI: 1.7-15.4dB), and middle ear mucosal pathology (P=0.03; 95% CI: 0.4-8.7dB) were associated with less improvement in ABG on multivariate regression. Autologous bone fused to the surrounding bone in 2 (28.6%) cases. There were 2 (2.7%) cases of TORP extrusion. TORPs may offer superior hearing outcomes compared with autologous grafting materials for total ossicular chain reconstruction. Patients with cholesteatoma and middle ear mucosal pathology have less favorable hearing outcomes. Bone frequently fuses to the surrounding bone in the middle ear and should be used with caution. Autologous cartilage reconstruction remains a reasonable option in high-risk ears or in patients where minimizing the risk of prosthesis extrusion or revision surgery is critical.