Does dynamic navigation system preserve more dentine? - A systematic review.

OBJECTIVE: This systematic review aims to comparatively analyse the amount of dentin removal by free hand and static guided endodontics with dynamic navigation system (DNS) in endodontic access cavity preparation. METHODS: The systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Based on the structured PICO framework of "Comparative evaluation of dynamic navigation system (I) to freehand (C) and static guided endodontics (C) in endodontic access cavity preparation on the preservation of tooth structure (O) when assessed on permanent human teeth (P)", the keywords were formulated and the articles were retrieved from three databases namely PubMed, Scopus and Embase, based on the keywords from the time of inception of DNS till June 2023. The risk of bias assessment was done using a modified Joanne Briggs Institute checklist, which evaluated domains such as randomisation, sample size, image acquisition using CBCT, angulation, accuracy and time taken. As the data was heterogenous, a quantitative meta-analysis was not performed. RESULTS: Initially, 174 articles were retrieved from the three databases, 30 duplicates were removed, after title check 108 articles were excluded and following abstract check only 10 articles qualified for full text analysis. On reviewing the 10 full text articles, 5 articles were excluded and the remaining 5 articles were subjected to the risk of bias analysis which showed that 2 articles displayed low risk of bias and three articles showed high risk of bias. The RoB analysis revealed that only 2 studies evaluated the preservation of dentin in terms of accuracy, angulation and time taken proving the increased precision with minimal loss of tooth structure using DNS. In both the studies, DNS proved to be superior to free hand technique in terms of precision, accuracy and efficiency in locating the canals during access cavity preparation with maximal preservation of tooth structure. CONCLUSION: With the minimal literature evidences, the present systematic review highlights maximal preservation of dentin using DNS. However, further invitro and invivo studies comparing the free hand, static guided endodontics to DNS must be carried out for its translation into clinical practice. CLINICAL SIGNIFICANCE: Dynamic navigation system provides maximal preservation of dentin during access cavity preparation.

Influence of cavity wall thickness on the color adjustment potential of single-shade resin composites.

BACKGROUND: The color adjustment potential of resin composites depends on the specific characteristics of the surrounding structures. The authors evaluated the influence of cavity wall thickness on CIEDE2000 color adjustment potential (CAP00) of single-shade composites using the CIEDE2000 color difference (ΔE00) formula. METHODS: Two types of specimens were produced: single, using Vittra APS color DA3 (FGM Dental), Vittra APS Unique (VU) (FGM Dental), and Omnichroma (Tokuyama Dental) composites; and dual, using Vittra APS color DA3, but with cavity wall thicknesses of 3, 2, or 1 mm, restored with VU or Omnichroma. CIEL∗a∗b∗ color coordinates were obtained from digital photographs of the specimens at different locations, and ΔE00 and CAP00 were calculated. Statistical analysis included 2-way analysis of variance, Kruskal-Wallis, Holm-Sidak, Student-Newman-Keuls, Wilcoxon signed rank, and paired t tests (α = 5%). RESULTS: Cavity walls 1-mm-thick had higher ΔE00 values and lower CAP00 values, particularly for VU (P < .05). Restorations matched better with the control at the periphery than the central area (P < .001). Overall ΔE00 means exceeded the color perceptibility threshold (ie, 0.8) and the acceptability threshold (ie, 1.8). Color differences (between center of restoration and control composite) were moderately unacceptable for 3-mm and 2-mm thicknesses and extremely unacceptable for 1-mm thickness. Both composites had a ΔE00 color shift predominately determined by means of the lightness difference. Positive CAP00 values were found for VU and Omnichroma. CONCLUSIONS: Wall thickness, especially at 1 mm, negatively impacted the color of single- shade composites. This effect was more pronounced for VU, affecting mainly the restoration's central area. PRACTICAL IMPLICATIONS: Color matching ability depends on the structural and material characteristics, and clinicians should be attentive to these factors when using single-shade resin composites.

Comparing accuracy in guided endodontics: dynamic real-time navigation, static guides, and manual approaches for access cavity preparation - an in vitro study using 3D printed teeth.

OBJECTIVES: To assess root canal localization accuracy using a dynamic approach, surgical guides and freehand technique in vitro. MATERIALS AND METHODS: Access cavities were prepared for 4 different 3D printed tooth types by 4 operators (n = 144). Deviations from the planning in angle and bur positioning were compared and operating time as well as tooth substance loss were evaluated (Kruskal-Wallis Test, ANOVA). Operating method, tooth type, and operator effects were analyzed (partial eta-squared statistic). RESULTS: Angle deviation varied significantly between the operating methods (p < .0001): freehand (9.53 ± 6.36°), dynamic (2.82 ± 1.8°) and static navigation (1.12 ± 0.85°). The highest effect size was calculated for operating method (ηP²=0.524), followed by tooth type (0.364), and operator (0.08). Regarding deviation of bur base and tip localization no significant difference was found between the methods. Operating method mainly influenced both parameters (ηP²=0.471, 0.379) with minor effects of tooth type (0.157) and operator. Freehand technique caused most substance loss (p < .001), dynamic navigation least (p < .0001). Operating time was the shortest for freehand followed by static and dynamic navigation. CONCLUSIONS: Guided endodontic access may aid in precise root canal localization and save tooth structure. CLINICAL RELEVANCE: Although guided endodontic access preparation may require more time compared to the freehand technique, the guided navigation is more accurate and saves tooth structure.

Assessment of Proximal Protection Usage by Dental Students During Class II Cavity Preparations: An In Vivo Pilot Study.

BACKGROUND: Class II cavity preparations in restorative dentistry pose a risk of iatrogenic damage to adjacent teeth as they could increase their susceptibility to caries and the need for additional restorative procedures. While previous research has explored this issue through in vitro and limited in vivo investigations, the direct clinical observation of proximal protection usage to prevent iatrogenic damage during class II cavity preparations is still limited. AIM: This in vivo study aimed to assess the prevalence of proximal protection usage and extent of iatrogenic damage induced to adjacent surfaces upon occurrence during class II cavity preparations via direct visual inspection under magnification. MATERIALS AND METHODS: Data were collected from restorative dentistry consultants supervising fourth-year undergraduate students. Information regarding cavity preparations, proximal protection usage, and iatrogenic damage was gathered through an electronic evaluation form via direct clinical observations once class II cavity preparations were finished. Statistical analyses, including ordinal logistic regression models, were employed to investigate associations and compute odds ratios (ORs). RESULTS: We examined 82 teeth adjacent to class II cavity preparations in in vivo settings. The prevalence of proximal protection use was 72%, while the prevalence of iatrogenic damage was 17.1% overall, increasing to 47.8% when not using protection and 5.1% when using protective measures. Polishing and restoration of the induced damage were the primary management approaches. The use of protective measures, particularly matrix bands, significantly reduced the risk of iatrogenic damage (P < 0.05). Several factors, including arch, tooth surface, time, operator gender, and the state of the adjacent tooth before treatment, were examined but did not yield statistically significant associations. CONCLUSION: Our study shows that most undergraduate dental students use proximal protection during class II cavity preparations, which are significant in reducing iatrogenic damage to the adjacent tooth. However, the literature shows that general practitioners often do not use proximal protection. The use of proximal protection should be reinforced and even required for the successful and safe treatment of proximal cavities. Future research with larger and more diverse samples is needed to understand the barriers to the use of proximal protection and develop interventions to promote its adoption.

Hardness and Depth of Cure of Conventional and Bulk-Fill Composite Resins in Class II Restorations with Transparent and Metal Matrix Strips.

Objectives: Hardness is relevant to the degree of conversion (DC) and depth of cure (DoC). The aim of this study was to determine the micro-hardness and DoC of conventional and bulk-fill composite resins in class II restorations using metal and clear matrix bands. Materials and Methods: Twelve specimens of each of the two composite resins, i.e., Filtek Z350 XT bulk-fill and Gradia posterior conventional composite, were prepared in the form of a class II cavity in a tooth mold, using a clear or metal matrix band. All specimens were cured and stored at 37°C for 24 hours. Vickers hardness was measured as a function of DoC at 2mm intervals. Data were analyzed by two-way ANOVA (alpha=0.05). Results: The bulk-fill composite exhibited significantly higher hardness levels than the conventional composite in all tested surfaces (P<0.001). However, while the metal matrix band had a significant impact on the bottom surface (P=0.059) and also on the furthest surface from the matrix and light source (P=0.04), it did not have a consistent effect across all tested surfaces. The simultaneous interaction of the composites and matrix band types in all surfaces, did not show significant differences in hardness values. The highest bottom-to-top surface hardness ratio (73%) was observed in the conventional composite near the metal matrix band. Conclusion: In deep class II cavities, the bottom-to-top surface hardness ratio did not reach the maximum of 80%, neither for bulk-fill nor conventional posterior composites. Therefore, in such cavities extended light-curing and more incremental composite placement is needed.

Shear bond strengths of bur or Er:YAG laser prepared dentine to composite resin with or without low-level laser conditioning: an in vitro study.

This study aims to compare the different modes of cavity preparation while evaluating the effect of low-level laser therapy (LLLT) on dentine before bonding in terms of shear bond strength between composite resin and dentine. Fifty human molar teeth were mounted on acrylic blocks and dentine specimen were prepared after which they were randomized into four equal groups. Cavity preparation mode differed in respective groups. After etching, bonding; composite resin was placed and polymerized on the prepared dentine surfaces. The specimens were kept in an environment simulating oral cavity and then shear tested in a universal testing machine. The failure surfaces of the specimen teeth were subjected to SEM micrographic evaluation. The cavity prepared with diamond abrasive points had a higher shearing load at failure that was statistically significantly different from the ones prepared with laser. That with diamond abrasive points followed by LLLT of the cavity surface with Nd:YAG laser had a higher bond strength than the ones prepared with just Er:YAG laser and there was no statistically significant difference between these and the ones prepared with diamond abrasive points alone. SEM analysis of the failure mode in bur-cut dentine showed the presence of a hybrid layer at the interface. Surface conditioning of the same with Nd:YAG laser before etching suggested a recrystallisation of dentine due to the heat produced. Cavity preparation with Er:YAG laser leads to reduced shear bond strength to adhesive restorative materials when compared with that using burs and high-speed handpiece.

Localization of senescent cells under cavity preparations in rats and restoration of reparative dentin formation by senolytics.

Reparative dentin formed by dental cavity preparation (DCP) is frequently used in clinical operations and plays a pivotal role in pulp protection. Recent reports have shown that senescent cells induced by various stressors aggravate many diseases. They can be treated using senolytics, which are drugs that selectively eliminate senescent cells. However, the association between DCP, senescent cells, and senolytics remains unclear. In this study, we established a rat model of DCP and analyzed the spatiotemporal localization of senescent cells in the pulp. The results showed that p21- and p16-positive senescent cells appeared mostly around the pulp horn (PH) under DCP. Furthermore, administration of senolytics (dasatinib and quercetin) successfully eliminated these senescent cells, thereby restoring the volume of reparative dentin formation. These data indicate that senescent cells induced by DCP may hamper the formation of reparative dentin. Senescent cells may be targets for the development of new restorative dentistry therapies.

Immunohistochemical localization of CD146 and alpha-smooth muscle actin during dentin formation and regeneration.

Cluster of differentiation 146 (CD146) is known to localize in stem cells and precursor cells of various tissues. In this study, to analyze the function of CD146 in odontoblast differentiation, immunohistochemical localization of CD146 was examined during rat molar tooth development and after cavity preparation. At the cap and bell stages, many CD146-positive cells were visible around the blood vessels in the dental papillae. On Postnatal day 2, osterix-positive odontoblasts were arranged in the dentin sialoprotein (DSP)-positive predentin, and many CD146-positive cells were observed near these odontoblasts with blood vessels. Some perivascular CD146-positive cells overlapped with Smad4-positive cells. However, the immunoreactivity for alpha-smooth muscle actin (α-SMA), one of the markers for undifferentiated cells, was negligible. Furthermore, the number of these cells decreased in the dental pulp on Postnatal day 28. On Day 4 after cavity preparation, Osterix-positive odontoblasts appeared lining the reparative dentin. Most of the blood vessels near the reparative dentin showed immunoreactivities for CD146. Reparative odontoblasts actively formed DSP-positive dentin matrix because these cells were positive for Smad4 and Osterix, but not for α-SMA. After 7 days, the number of CD146-positive cells near blood vessels decreased in the dental pulp beneath the cavity. These results suggest that the CD146 is expressed in the perivascular area of the dental pulp and induces vascularization in the vicinity of dentin formation, and some CD146-positive cells are activated by the bone morphogenetic protein signaling pathway and differentiate into odontoblasts in the early stages of dentin formation and repair.

Design of an interactive system for access cavity assessment: A novel feedback tool for preclinical endodontics.

INTRODUCTION: A software program was developed to provide visual, guided feedback to students for access cavity preparations in preclinical learning. The specific aim of the study was to investigate students' overall experiences with the new learning method and compare their experiences with traditional teaching. MATERIALS AND METHODS: A workflow based on freely available software was designed to interactively register three-dimensional models of molars with access cavities, and to metrically compare these to instructor-prepared standard cavities. Third-year students practicing molar endodontics access cavity preparation in the preclinical course were then surveyed. A total of 44/79 students completed self-administered questionnaires prior and after the use of the feedback software to gauge their learning experience. RESULTS: The results of the post-training questionnaire illustrated that all surveyed students agreed/strongly agreed that the software assisted their learning in access cavity preparation. In addition, 86 and 89%, respectively, of students agreed that the use of the software improved their skills of access cavity preparation and felt more confident about their access cavity preparation skills after using the software package, 3D Dental Align. DISCUSSION: The presented software solution permitted setting and comparing access cavity preparations by students against a standard access prepared by an instructor. The process of data acquisition and registration was fast and straightforward. Student feedback was very positive and suggested the integration of this type of experiential learning into the preclinical curriculum. CONCLUSION: This feasibility study demonstrated the utility of the new technology to assist dental students' access cavity preparation learning.

A 12-month Follow-Up Study of Pulp Oxygen Saturation in Deciduous Molars After Selective and Nonselective Carious-Tissue Removal: A Randomized Pilot Trial

ABSTRACT Objective: To compare the pulp vitality of deciduous molars before and after selective caries removal (SCR) or nonselective caries removal to hard dentin (NSCR) over one year, using oxygen saturation percentage (%SaO2). Material and Methods: Deciduous molars with deep occlusal/proximal-occlusal caries lesions were randomized to SCR (n=22) or NSCR groups (n=22). After the caries removal, the teeth were protected with calcium hydroxide cement and restored with composite resin (Filtek Z250). The pulp condition diagnosis was evaluated at baseline, immediately after caries removal, and follow-up (7 days, 1-, 6- and 12-months) by %SaO2. Pulp exposure and pulp necrosis were primary outcomes, and %SaO2 was secondary. Results: Intraoperative pulp exposure occurred in four teeth of the NSCR group (18.2%) and one tooth of the SCR group (4.5%) (p>0.05). Two cases of pulp necrosis occurred in the NSCR group (10%). No difference in %SaO2 pulp was observed in the inter-and intragroup comparison over time (p>0.05). Conclusion: Advantageously, the %SaO2 minimizes preoperatory pulp vitality diagnosis subjectivity before SCR/ NSCR treatments. Furthermore, the pilot study results suggest the pulp response of deciduous molars, when evaluated by clinical, radiographic, and pulp %SaO2 seems not to differ between teeth treated with SCR or NSCR.

Comparative evaluation of fracture resistance of endodontically treated maxillary premolars reinforced by customized glass fiber post in two different ways: An in vitro study.

Context: Endodontically treated premolars are currently restored with direct bonded techniques in conservative manner enabling them to bear functional stresses homogeneously. Aim: The study aimed to evaluate the effect of placement of compactable glass fibers in reinforcing the endodontically treated teeth in a novel conservative manner. Settings and Design: Research laboratory, in vitro study. Materials and Methods: Seventy-five extracted maxillary premolars were procured. Fifteen teeth were left untreated (Group A) and the remaining teeth were endodontically treated followed by standardized mesio-occluso-distal preparation and randomly assigned to experimental groups (n = 15) as follows: (B) no restoration, (C) restoration with composite, (D) EverStick® POST followed by composite, and (E) vertical glass fibers within 3 mm of the coronal root canal space and buccopalatal flaring of the coronal fibers followed by composite. After conditioning and thermocycling, specimens were loaded under a universal testing machine to evaluate fracture resistance and fracture pattern of specimens. Statistical Analysis Used: Obtained scores were statistically analyzed using one-way analysis of variance test for stress analysis, post hoc Tukey's test for intergroup comparison, and Chi-square test for analysis of favorable and unfavorable fracture. Results: The fracture resistance was highest to lowest as follows: Group A > E > C > D > B (P < 0.001). Conclusion: EverStick®POST used in conservative manner improved fracture strength of teeth significantly.

Bond strength of bulk-fill resin composites: the effect of cavity preparation and aging

Aim: Evaluating the resin-dentin bond strength of Class II conventional and bulk-fill composite restorations, using different cavity sizes before and after aging. Methods: Seventy-five human molars were distributed into groups according to the buccolingual width of the cavities, conservative (n=25) and extended (n=50). They were divided according to the restorative material: conventional (Z100/control group) or bulk-fill resin composites (Filtek Bulk Fill/FBF; Tetric N Ceram Bulk Fill/TNCBF; Filtek Bulk Fill Flow/FBFF; Surefill SDR flow/SDR). The restored teeth were sectioned on sticks (n=50 per restorative materials + width cavities group), half were stored in Water/Ethanol 75% for 30 days and the other half were submitted to the immediate microtensile bond strength (µTBS) test. Data were analyzed applying the Three-Way Analysis of Variance (ANOVA), Bonferroni test, test t, and Weibull analyses (p<0.05). Results: SDR and FBF presented lower µTBSvalues for extended preparation when compared to the conservative preparation, before aging. After aging, only for the FBFF, a decrease in the µTBSvalues was observed. Comparing the µTBSvalues, before and after aging, the SDR demonstrated lower µTBSvalues after aging when the conservative cavity was used. A decrease in the µTBSvalues was observed for the Z100, the FBF and, the FBFF, after aging, when the extended cavity was used. Conclusion: The effect of cavity preparation and aging on the resin-dentin of Class II is material dependent. Most of the bulk-fill resin composites evaluated presented a similar performance to the conventional resin composites for all the conditions of this study

Virtual 3D tooth creation for personized haptic simulation training in access cavity preparation.

Personalized medicine is a new medical concept to achieve patient-centered care. In dentistry, it is recognized for the customization of operative strategies and managements for oral diseases. Access cavity preparation in endodontic treatment is an irreversible procedure. Endodontic training will be more realistic by the implementation of clinical relevant 3D virtual reality technology. In this article, the authors first presented a personized case from a real patient to provide assess cavity preparation in haptic virtual reality dental simulator Simodont® (Nissin Dental Products Inc., Nieuw-Vennep, Netherlands). The practical framework to generate STL from cone beam computed tomography was demonstrated. A case of virtual tooth #26 access cavity preparation in Simodont® was established for trainee unlimited practices before performing the clinical procedure on a real patient. Taken together, access cavity preparation in a virtual environment using a 3D personized tooth may minimize procedural errors and facilitate clinical treatment outcome.

In vitro Evaluation of Laser vs. Handpiece for Tooth Preparation.

Background: The erbium-doped yttrium aluminium garnet (Er:YAG) laser has been revealed to effectively ablate dental hard tissues, and its utilisation to caries eradication and cavity preparation is envisaged. Nevertheless, only a limited research has been performed on the Er:YAG laser's capacity to treat caries. Aim and Objectives: The efficiency of caries elimination with an Er:YAG laser in vitro was equated to that of traditional mechanical therapy in this study. Methodology: The investigation made use of teeth that had suffered from root caries. The Er:YAG laser was used to treat half of each tooth, while the other half was either removed with a conventional bur or left untouched as a control. Each therapy was evaluated in terms of how long it took to remove cavities, histological examinations of decalcified serial sections, scanning electron microscopy (SEM) analyses and the density of the dentin. Result: A longer treatment time was required for the Er:YAG laser to completely eradicate carious dentin because of its precise irradiation strategy. However, the Er:YAG laser was effective in removing diseased and softening carious dentin with little heat injury to neighbouring intact dentin, much as the bur treatment. It was also shown that the Er:YAG laser treatment had a lower amount of vibration than other methods. The SEM study of the lased dentin surface revealed characteristic micro-irregularities. Conclusion: The Er:YAG laser system appears to be a potential novel technical option for caries therapy, based on our findings.

Effect of Erbium, Chromium-doped: Yttrium, Scandium, Gallium and Garnet Laser Tooth Preparation on Gap Formation of Universal Adhesive Bonded to Enamel and Dentin: A Micro-CT and SEM Study.

Introduction: The presence of gaps at the bonding interface of resin composite restorations is known to have an impact on restoration longevity. This study aimed to evaluate the effect of erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er, Cr:YSGG) laser irradiation on gap formation at the tooth-resin interface and to compare the reliability of micro-computed tomography (µCT) and scanning electron microscopy (SEM) scans for gap formation assessment. Methods: Thirty standardized non-retentive class V cavities were prepared on sound human premolars using either an Er,Cr:YSGG laser or a round carbide bur (n=15 for each). A universal adhesive and A nano-filled resin composite were applied in accordance with the manufacturer's recommendations. After water storage for 24 hours at 37°C, the teeth were subjected to thermocycling. Gap formation assessments were performed by µCT (Skyscan 1173 µCT, Brucker, Belgium) and SEM (JEOL JSM-6610LV, Japan), and SPSS version 24.0 (IBM Inc., Chicago, USA) was used to analyze the data at P value<0.05. Descriptive statistics were used to describe the gap formation percentages. To compare the impact of both preparation and assessment methods, a non-parametric Mann-Whitney U test was used. Results: In enamel, similar gap formation values were detected for the two preparation methods (bur and laser). However, the laser-prepared group showed higher gap formation values in dentin. Additionally, higher gap formation values were reported for both preparation methods when µCT was used for assessment. Conclusion: Cavity preparation using a Waterlase laser led to higher gap formation percentages at the dentin-resin interface. In addition, SEM assessment is more reliable for assessing the tooth-resin interface.

Facilitation of Reparative Dentin Using a Drug Repositioning Approach With 4-Phenylbutric Acid.

For hard tissue formation, cellular mechanisms, involved in protein folding, processing, and secretion play important roles in the endoplasmic reticulum (ER). In pathological and regeneration conditions, ER stress hinders proper formation and secretion of proteins, and tissue regeneration by unfolded protein synthesis. 4-Phenylbutyric acid (4PBA) is a chemical chaperone that alleviates ER stress through modulation in proteins folding and protein trafficking. However, previous studies about 4PBA only focused on the metabolic diseases rather than on hard tissue formation and regeneration. Herein, we evaluated the function of 4PBA in dentin regeneration using an exposed pulp animal model system via a local delivery method as a drug repositioning strategy. Our results showed altered morphological changes and cellular physiology with histology and immunohistochemistry. The 4PBA treatment modulated the inflammation reaction and resolved ER stress in the early stage of pulp exposure. In addition, 4PBA treatment activated blood vessel formation and TGF-ß1 expression in the dentin-pulp complex. Micro-computed tomography and histological examinations confirmed the facilitated formation of the dentin bridge in the 4PBA-treated specimens. These results suggest that proper modulation of ER stress would be an important factor for secretion and patterned formation in dentin regeneration.

Present status and future directions - Minimal endodontic access cavities.

In the last decades, the move of medicine towards minimally invasive treatments is notorious and scientifically grounded. As dentistry naturally follows in its footsteps, minimal access preparation have also becume a trend topic in the endodontic field. This procedure aims to maximize preservation of dentine tissue backed up by the idea that this is an effective way to reduce the incidence of post-treatment tooth fracture. However, with the assessment of the body of evidence on this topic, it is possible to observe some key points (a) the demand for nomenclature standardization, (b) the requirement of specific tools such as ultra-flexible instruments, visual magnification, superior illumination, and three-dimensional imaging technology, (c) minimally invasive treatment does not seem to affect orifice location and mechanical preparation when using adequate armamentarium, but it (d) may impair adequate canal cleaning, disinfection and filling procedures, and also (e) it displays contradictory results regarding the ability to increase the tooth strengthen compared to the traditional access cavity. In spite of that, it is undeniable that methodological flaws of some benchtop studies using extracted teeth may be responsible for the conflicting data, thus triggering the need for more sophisticated devices/facilities and specifically designed research in an attempt to make clear the role of the access size/design on long-term teeth survival. Moreover, it is inevitable that a clinical approach such as minimal endodontic access cavities that demands complex tools and skilled and experienced operators bring to the fore doubts on its educational impact mainly when confronted with the conflicting scientific output, ultimately provoking a cost-benefit analysis of its implementation as a routine technique. In addition, this review discusses the ongoing scientific and clinical status of minimally invasive access cavities aiming to input an in-depth and unbiased view over the rationale behind them, uncovering not only the related conceptual and scientific flaws but also outlining future directions for research and clinical practices. The conclusions attempt to skip from passionate disputes highlighting the current body of evidence as weak and incomplete to guide decision making, demanding the development of a close-to-in situ laboratory model or a large and well-controlled clinical trial to solve this matter.

Exploration of the role of the subodontoblastic layer in odontoblast-like cell differentiation after tooth drilling using Nestin-enhanced green fluorescent protein transgenic mice.

OBJECTIVES: Original odontoblasts and regenerated odontoblast-like cells (OBLCs) may differently regulate Nestin expression. This study aimed to investigate the role of the subodontoblastic layer (SOBL) using green fluorescent protein (GFP) reactivity in the process of OBLC differentiation after tooth drilling in Nestin-enhanced GFP transgenic mice. METHODS: A groove-shaped cavity was prepared on the mesial surface of the maxillary first molars of 5- or 6-week-old mice under deep anesthesia. Immunohistochemical staining for Nestin and GFP and Nestin in situ hybridization were conducted on the sections obtained at 1-14 days postoperative. RESULTS: Odontoblasts showed intense endogenous Nestin protein and mRNA expression, whereas the coronal SOBL cells showed a Nestin-GFP-positive reaction in the control groups. The injured odontoblasts had significantly decreased Nestin immunoreactivity as well as decreased expression of Nestin mRNA 1-2 days after the injury; subsequently, newly differentiated OBLCs were arranged along the pulp-dentin border, with significantly increased Nestin expression as well as increased expression of Nestin mRNA on days 3-5 to form reparative dentin. Nestin-GFP-positive cells at the pulp-dentin border significantly increased in number on days 1 and 2. GFP(+)/Nestin(+) and GFP(-)/Nestin(+) cells were intermingled in the newly differentiated OBLCs. CONCLUSIONS: The commitment of Nestin-GFP-positive cells into Nestin-positive OBLCs suggests that the restriction of endogenous Nestin protein and mRNA expression in the static SOBL cells was removed by exogenous stimuli, resulting in their migration along the pulp-dentin border and their differentiation into OBLCs.

Does selective caries removal in combination with antimicrobial photodynamic therapy affect the clinical performance of adhesive restorations of primary or permanent teeth? A systematic review with meta-analysis.

Antimicrobial photodynamic therapy (aPDT) is an adjunct to a selective caries removal (SCR) technique for deep caries lesion treatment. The knowledge about chemical and structural changes affecting the remaining dentin surface after the use of this therapy is still unknown. OBJECTIVE: to answer the following question: Does the SCR technique in combination with aPDT affect the clinical performance of adhesive restorations in deep carious lesions of primary or permanent teeth? STUDY DESIGN: a systematic review was conducted. Five databases, supplemented by trial registers, google scholar, manual search, personal communications, and grey literature were investigated. Randomized clinical trials were included. Two independent reviewers selected the studies, extracted qualitatively the data, and evaluated the risk of bias (using Cochrane Collaboration's tool and Robot Reviewer program). The certainty of the evidence was accessed based on The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. A meta-analysis of comparable data was performed with RevMan software 5.3. RESULTS: A total of 39 articles and 3 studies were found. The final selection included 3 articles with a total of 82 participants. No studies were found on permanent teeth. The studies presented low risk of bias. Considering the treatment in the experimental (SCR + aPDT) or control groups (SCR), no difference on clinical performance of adhesive restorations in deep caries of primary teeth was observed after 6 months (p = 0.78; CI -0.01 (-0.09, 0.07)) or 12 months (p =0.75; CI -0.02 (-0.12, 0.08)). All outcomes presented moderate certainty of evidence mainly due to the small sample size that downgrade the GRADE scores. CONCLUSIONS: based on moderate certainty of the evidence, the clinical use of aPDT as an adjuvant of SCR has potential indication for treatment in deep caries of primary teeth. However, studies with more follow up and on permanent teeth are missing with the necessity for further research.

Effect of laser-assisted retrograde cavity preparation on push-out-bond-strength of mineral trioxide aggregate and calcium-enriched-mixture-cement / Efeito de preparo cavitário retrógrado assistido por laser na força de união de cimento de agregado trióxido mineral e cimento enriquecido com cálcio

Objective: This study aimed to determine the push-out-bond-strength(PBS) of mineral trioxide aggregate (BIOMTA+) and calcium-enriched-mixture-cement (CEM) in retrograde cavities prepared using Er: YAG laser and stainless-steel bur. Material and Methods: The root canals of 60 extracted single-rooted human teeth were prepared, filled and their apical portion of 3-mm were resected using a diamond bur and randomly divided into four groups according to technique of retrograde preparation and filling material as follows(n=15): Group1: bur/ BIOMTA+ ,Group2: bur/ CEM, Group3: Er:YAG laser/ BIOMTA+, Group4: Er:YAG laser/ CEM. PBS test were performed to specimens and failure modes were evaluated. The data were statistically analyzed with ANOVA, Post-Hoc Tukey and t tests (p< 0.05). Results: CEM was exhibited higher than bond strength compared to BIOMTA+ in retrograde cavity prepared using laser (p= 0.021) and BIOMTA+ in retrograde cavity prepared using bur was exhibited higher than bond strength compared to in retrograde cavities prepared using laser (p= 0.024). Failure modes were dominantly cohesive in all groups tested and one representative specimen each failure mode was examined in SEM and the general characteristics of the failure modes were confirmed. Conclusion: With in the limitations of the present study, when used CEM, Er: YAG laser-assisted retrograde cavity preparation positively affected the bond strength values compared to BIO MTA+. Considering its optimal adhesion, the calcium-enriched-mixture-cement (CEM) might be a good option as a filling material in retrograde cavities in clinical use. (AU)

Objetivo: O objetivo deste estudo foi determinar a força de união (PBS) de cimento de agregado trióxido mineral (BIO MTA+) e cimento enriquecido com cálcio (CEM) em preparos cavitários retrógrados realizados com: Laser Er-YAG e brocas de aço inoxidável. Material e Métodos: Canais radiculares de 60 dentes unirradiculares extraídos foram preparados, preenchidos e 3 mm de suas porções apicais foram ressecadas usando uma broca diamantada e divididos randomicamente em quatro grupos de acordo com a técnica de preparação retrógrada e o material de preenchimento (n=15): Grupo 1: Broca/BIO MTA+, Grupo 2: Broca/CEM, Grupo 3: Laser Er-YAG/BIO MTA+, Grupo 4: Laser Er-YAG/CEM. O teste de PBS foi realizado para as amostras e os modelos de falha foram avaliados. Os dados foram analisados estatisticamente pelos testes de ANOVA, Post-Hoc Tukey e testes t (p< 0.05). Resultados: CEM apresentou maior força de união que BIO MTA+ em cavidades retrógradas preparadas com laser (p= 0.021) e BIO MTA+ em cavidades retrógradas preparadas com brocas apresentou maior força de união quando comparado à cavidades retrógradas preparadas com laser (p= 0.024). Os modelos de falha foram predominantemente coesos em todos os grupos testados e um espécime representativo de cada modelo de falha foi examinado em MEV e as características gerais dos modelos de falha foram confirmadas. Conclusão: Com as limitações do presente estudo, quando usou-se CEM, o preparo de cavidades retrógradas através de Laser Er-YAG afetou positivamente os valores da força de união quando comparados com BIO MTA+. Considerando sua ótima adesão, o cimento enriquecido com cálcio (CEM) pode ser uma boa opção como um material de preenchimento em cavidades retrógradas no uso clínico.