José Antonio González Sánchez

Background: Orthodontically induced external root resorption (ERR) may affect long-term tooth stability, requiring a reliable assessment of root length changes. This study developed an artificial intelligence (AI)-based framework for automatic segmentation and quantitative evaluation of root resorption, comparing fixed appliances and clear aligner therapy. Methods: A dataset of 100 anonymised orthopantomographic (OPG) radiographs (50 fixed appliance, 50 clear aligner) obtained before and after orthodontic treatment was analysed. A U-Net model was trained for automatic tooth segmentation and quantitative assessment of tooth length changes. Measurements were computed from both AI-predicted and Dentist-annotated masks using pixel-based Python analysis (Python version 3.6), and pre-post differences were compared between methods. Results: The segmentation model achieved high performance with Intersection over Union values up to 89% and Dice Similarity Coefficients up to 95%. Quantitative analysis demonstrated significant reductions in root length following orthodontic treatment in both modalities (p < 0.0001). In the fixed appliance group, AI-based measurements showed an average root length reduction of 8.95%, while human measurements indicated a reduction of 10.16%. In the clear aligner group, AI measurements demonstrated a reduction of 2.81%, compared with 4.98% in human measurements. Root resorption was significantly greater in the fixed appliance group than in the clear aligner group (p < 0.0001). AI-derived measurements showed strong agreement with expert evaluations. Conclusions: AI-based analysis of panoramic radiographs may provide a reliable and reproducible approach for quantifying orthodontically induced root resorption. The findings suggest that clear aligner therapy was associated with lower root length reduction; however, larger multi-centre studies and external validation are required before clinical implementation.

Background/Objectives: Clear aligners (CAs) are a popular alternative to classical fixed appliances (FAs) for orthodontic treatment. This systematic review aimed to compare the external apical root resorption (EARR) in patients undergoing orthodontic therapy with either FAs or removable CAs. Methods: An electronic search was conducted to identify comparative studies. Risk of bias was assessed using the Cochrane RoB 2.0 tool for randomized controlled trials (RCTs) and the ROBINS-I tool for non-RCTs. EARR at the following incisors was considered: maxillary central (MxC), maxillary lateral (MxL), mandibular central (MdC), and mandibular lateral (MdL). A random-effects meta-analysis was performed, and mean differences were estimated. Results: Ten studies (one RCT, two prospective, and seven retrospective studies) were included. Four had a low risk of bias, four had a moderate risk, and two had a serious concern. In total, 286 patients (1476 incisors) and 289 patients (1487 incisors) in the CA and FA groups were considered, respectively. The mean follow-up was 22.7 ± 9.9 (standard deviation) in the CA group and 22.5 ± 8.2 months in the FA group. The meta-analysis found that CAs caused significantly less EARR than FAs for all tooth types except for MdL. On a patient basis, the mean difference (MD) in favour of CAs ranged from −0.64 mm (95% CI (confidence interval): −0.90, −0.38 mm) for MxC to −0.26 mm (95% CI: −0.43, −0.09 mm) in MdC. Heterogeneity across studies was generally high, except for MdC cases. Conclusions: EARR at incisor teeth is generally lower using CAs compared to FAs. Further evidence-based studies are needed to confirm these results and understand the clinical relevance of such a difference.

Aim: To characterise and evaluate mucoadhesive strength and antibacterial properties of a nanotechnological formulation for endodontic disinfection based on biodegradable nanoparticles dispersed in a thermosensitive gel containing calcium hydroxide (Ca(OH) ₂ ‐NPs‐gel). Methodology: Morphology of Ca(OH) ₂ ‐NPs‐gel was studied using transmission electron microscopy. Moreover, Ca(OH) ₂ ‐NPs‐gel was sterilised using gamma irradiation (25 kGy), and the stability after the sterilisation process was studied by measuring Ca(OH) ₂ ‐NPs‐gel average size, polydispersity index, zeta potential and encapsulation efficiency. To assess the ex vivo mucoadhesive strength, extracted single‐rooted human teeth were used to measure the force necessary to separate the formulation from the teeth. In addition, the short‐time stability of Ca(OH) ₂ ‐NPs‐gel was evaluated monthly, analysing entrapment efficacy, backscattering and transmittance of Ca(OH) ₂ ‐NPs‐gel stored at different temperatures (4°C, 25°C and 37°C). Furthermore, the antibacterial analysis of Ca(OH) ₂ ‐NPs‐gel was performed against Enterococcus faecalis inoculated in extracted human single‐root teeth and evaluated by confocal and scanning electron microscopy. Finally, the metabolic activity of bacteria was studied through a resazurin assay to evaluate bacterial survival after treatment. Results: Ca(OH) ₂ ‐NPs‐gel owned a round shape and a smooth surface without particle aggregation. Sterilisation did not induce an alteration in Ca(OH) ₂ ‐NPs‐gel physicochemical properties and Ca(OH) ₂ ‐NPs‐gel presented a high adhesion strength. In addition, 4°C was the best temperature to store Ca(OH) ₂ ‐NPs‐gel. Regarding the antibacterial therapeutic efficacy, Ca(OH) ₂ ‐NPs‐gel possesses suitable antibacterial properties, indicating that it efficiently reduces bacterial biofilms. Conclusion: Calcium hydroxide‐loaded PLGA nanoparticles dispersed in a thermosensitive gel have been developed, optimised and characterised, obtaining excellent antibacterial properties and achieving bacterial disinfection levels similar to those of commercial formulations.

Aim: The aim of current study is the development and optimization of biodegradable polymeric nanoparticles (NPs) to be used in the field of Endodontics as intracanal medication in cases of avulsed teeth with extended extra‐oral time, utilizing PLGA polymers loaded with the anti‐inflammatory drug clobetasol propionate (CP). Methodology: CP‐loaded nanoparticles (CP‐NPs) were prepared using the solvent displacement method. CP release profile from CP‐NPs was assessed for 48 h against free CP. Using extracted human teeth, the degree of infiltration inside the dentinal tubules was studied for both CP‐NPs and CP. The anti‐inflammatory capacity of CP‐NPs was evaluated in vitro measuring their response and reaction against inflammatory cells, in particular against macrophages. The enzyme‐linked immunosorbent assay (ELISA) was used to examine the cytokine release of IL‐1β and TNF‐α. Results: Optimized CP‐NPs displayed an average size below 200 nm and a monomodal population. Additionally, spherical morphology and non‐aggregation of CP‐NPs were confirmed by transmission electron microscopy. Interaction studies showed that CP was encapsulated inside the NPs and no covalent bonds were formed. Moreover, CP‐NPs exhibited a prolonged and steady release with only 21% of the encapsulated CP released after 48 h. Using confocal laser scanning microscopy, it was observed that CP‐NPs were able to display enhanced penetration into the dentinal tubules. Neither the release of TNF‐α nor IL‐1β increased in CP‐NPs compared to the LPS control, displaying results similar and even less than the TCP after 48 h. Moreover, IL‐1β release in LPS‐stimulated cells, decreased when macrophages were treated with CP‐NPs. Conclusions: In the present work, CP‐NPs were prepared, optimized and characterized displaying significant increase in the degree of infiltration inside the dentinal tubules against CP and were able to significantly reduce TNF‐α release. Therefore, CP‐NPs constitute a promising therapy for the treatment of avulsed teeth with extended extra‐oral time.

Objective The aim of this study was to evaluate six files on the pericervical dentin (PCD) and the smallest dentin thickness zones (SDTZ) in mesial root canals of mandibular molars. Materials and methods Sixty mandibular molars with two mesial canals and Vertucci configuration were aleatory allocated in 6 experimental groups of 10 molars and 20 root canals. Specimens were scanned before instrumentation using the SkyScan 1275 (Bruker microCT, Kontich, Belgium). Group 1 was treated with WaveOne Gold (WG), group 2 with Reciproc Blue (RB), group 3 with TRUShape (TS), group 4 with XP-endo Shaper (XP), group 5 with iRace (IR), and group 6 with TruNatomy (TN). After instrumentation, the molars were scanned again and the images recorded were reconstructed with the NRecon v.1.7 (Bruker micro-CT) and analyzed with CTAn v.1.20.8 software (Bruker micro-CT) quantifying the changes produced in the surface, volume, structure thickness, SMI, and centroids at the Pericervical Dentin area of the root canals (PCD) located from the root canal orifices at the floor of the pulp chamber to 4 mm in the apical direction, and the changes in the Smallest Dentin Thickness Zones (SDTZ) located (from the furcation to 4 mm and 7 mm in the apical direction. The data obtained were compared using Wilcoxon and ANOVA with a 5% significance level. Results XP and TN were similar in all the parameters (P >.05) at the PCD, but TN showed significant differences from WG, RB, TS, and IR (P <.05), while XP showed significant differences from WG (P <.05) in volume, surface, and structure thickness. Regarding the changes in the SDTZ, the amount of dentin removed was similar between the groups in both canals at the middle 1/3, at the cervical 1/3 for MB canals, and in ML canals for RB, TS, XP, IR, and TN (P>.05). The action of WG was significantly different from that of XP and TN in the cervical 1/3 of the ML canal (P <.05). Conclusions XP and TN rotatory files with small taper and volume maintained better with minor changes at the PCD and SDTZ, while WG reciprocation file produced the largest change. All the files were maintained centered at the PCD, and their performances were safe with a minimal thickness higher 0.5 mm at the SDTZ, and without risk of perforation. Trial registration No clinical trials were indicated in this study. Clinical relevance The choice of endodontic files is a relevant factor in the conservative performance of root canal treatments.

Aim: Design, produce and assess the viability of a novel nanotechnological antibacterial thermo‐sensible intracanal medicament This involves encapsulating calcium hydroxide (Ca(OH)₂) within polylactic‐co‐glycolic acid (PLGA) nanoparticles (NPs) and dispersing them in a thermosensitive gel (Ca(OH)₂‐NPs‐gel). In addition, perform in vitro and ex vivo assessments to evaluate tissue irritation and penetration capacity into dentinal tubules in comparison to free Ca(OH)₂.Methodology: Reproducibility of Ca(OH)₂‐NPs was confirmed by obtaining the average size of the NPs, their polydispersity index, zeta potential and entrapment efficiency. Moreover, rheological studies of Ca(OH)₂‐NPs‐gel were carried out with a rheometer, studying the oscillatory stress sweep, the mean viscosity value, frequency and temperature sweeps. Tolerance was assessed using the membrane of an embryonated chicken egg. In vitro Ca(OH)₂ release was studied by direct dialysis in an aqueous media monitoring the amount of Ca(OH)₂ released. Six extracted human teeth were used to study the depth of penetration of fluorescently labelled Ca(OH)₂‐NPs‐gel into the dentinal tubules and significant differences against free Ca(OH)₂ were calculated using one‐way anova.Results: Ca(OH)₂‐NPs‐gel demonstrated to be highly reproducible with an average size below 200 nm, a homogeneous NPs population, negative surface charge and high entrapment efficiency. The analysis of the thermosensitive gel allowed us to determine its rheological characteristics, showing that at 10°C gels owned a fluid‐like behaviour meanwhile at 37°C they owned an elastic‐like behaviour. Ca(OH)₂‐NPs‐gel showed a prolonged drug release and the depth of penetration inside the dentinal tubules increased in the most apical areas. In addition, it was found that this drug did not produce irritation when applied to tissues such as eggs' chorialantoidonic membrane.Conclusion: Calcium hydroxide‐loaded PLGA NPs dispersed in a thermosensitive gel may constitute a suitable alternative as an intracanal antibacterial medicament.

Objectives: The aim of this study was to evaluate six files on the pericervical dentin (PCD) and the smallest dentin thickness zones (SDTZ) in mesial root canals of mandibular molars. Materials and Methods: Sixty mesial roots with 2 canals were scanned before and after instrumentation with WaveOne Gold (WG), Reciproc Blue (RB), TRUShape (TS), XP-endo Shaper (XP), iRace (IR), and TruNatomy (TN). Surface, volume, structure thickness, SMI, and centroids were evaluated at the PCD, and the changes in the SDTZ were quantified. The data obtained werecompared using Wilcoxon and ANOVA with a 5% significance level. Results: XP and TN were similar in all the parameters (P >.05) at the PCD, but TN showed significant differences from WG, RB, TS, and IR (P <.05), while XP showed significant differences from WG (P <.05) in volume, surface, and structure thickness. Regarding the changes in the SDTZ, the amount of dentin removed was similar between the groups in both canals at the middle 1/3, at the cervical 1/3 for MB canals, and in ML canals for RB, TS, XP, IR, and TN (P>.05). The action of WG was significantly different from that of XP and TN in the cervical 1/3 of the ML canal (P <.05). Conclusions: XP and TN maintained better the anatomy, with minor changes at the PCD and SDTZ, while WG produced the largest changes. Centering at the PCD was maintained with all the files, and their performances were safe without risk of perforation. Clinical Relevance: The choice of endodontic files is a relevant factor in the conservative performance of root canal treatments. Trial Registration: No clinical trials were indicated in this study