Assessment of dental pulp response to carries via MR T2mapping and histological analysis.

OBJECTIVES: The aim of our study was to assess the correlation between T2 relaxation times and their variability with the histopathological results of the same teeth in relation to caries progression. MATERIALS AND METHODS: 52 extracted permanent premolars were included in the study. Prior to extractions, patients underwent magnetic resonance imaging (MRI) scanning and teeth were evaluated using ICDAS classification. Pulps of extracted teeth were histologically analysed. RESULTS: MRI T2 relaxation times (ms) were 111,9 ± 11.2 for ICDAS 0, 132.3 ± 18.5* for ICDAS 1, 124.6 ± 14.8 for ICDAS 2 and 112. 6 ± 18.2 for ICDAS 3 group (p = 0,013). A positive correlation was observed between MRI T2 relaxation times and macrophage and T lymphocyte density in healthy teeth. There was a positive correlation between vascular density and T2 relaxation times of dental pulp in teeth with ICDAS score 1. A negative correlation was found between T2 relaxation times and macrophage density. There was a positive correlation between T2 relaxation time variability and macrophage and T lymphocyte density in teeth with ICDAS score 2. In teeth with ICDAS score 3, a positive correlation between T2 relaxation times and T2 relaxation time variability and lymphocyte B density was found. CONCLUSION: The results of our study confirm the applicability of MRI in evaluation of the true condition of the pulp tissue. CLINICAL RELEVANCE: With the high correlation to histological validation, MRI method serves as a promising imaging implement in the field of general dentistry and endodontics.

Use of micro-computed tomography and scanning electron microscopy with energy-dispersive spectroscopy to distinguish natural white spot enamel lesions from sound enamel in human premolars.

PURPOSE: The aim of the present study was to develop a novel method for distinguishing white spot lesions (WSLs) from sound enamel in human premolars using micro-computed tomography (micro-CT) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and to examine differences in surface morphology, chemical composition, and mineral density (MD) between these two areas. METHODS: Fourteen premolars with natural WSLs on the enamel surface of the crowns were examined. After sectioning the teeth, each specimen containing WSLs adjacent to intact enamel was examined for MD, surface morphology, and atomic percentages (At%) of chemical components using micro-CT and SEM/EDS, respectively. Differences between these areas of the same specimen were analyzed statistically using paired t-test. RESULTS: SEM images highlighted increased roughness and irregularity in the lesion area. EDS analysis revealed significant reductions in calcium (Ca), phosphorus (P), fluorine (F), chlorine (Cl), and sodium (Na) levels at the lesion surface in comparison to intact enamel (P < 0.05). The decreases in the MD of the lesions were statistically significant in comparison to sound enamel (P < 0.05). CONCLUSION: These findings provide standard measurements for evaluating the essential characteristics of WSLs and intact enamel, being vital for assessment of treatment outcomes and development of innovative biomaterials for management of hypo-mineralized enamel lesions.

Impact of toothbrush head configuration and dentifrice abrasivity on non-carious cervical lesions in-vitro.

OBJECTIVE: To investigate the effect of toothbrush head configuration and dentifrice slurry abrasivity on the development of simulated non-carious cervical lesions (NCCLs) in vitro. METHODS: Extracted premolars were randomly allocated into 15 groups (n = 16) generated by the association between toothbrush head configuration (flat-trimmed, rippled, cross-angled/multilevel/rubbers added, cross-angled/multilevel/flex head, feathered) and dentifrice slurry abrasivity (low/medium/high). Teeth were mounted on acrylic blocks and had their roots partially covered with acrylic resin, leaving 2-mm root surfaces exposed. Toothbrushing was performed for 35,000 and 65,000 double-strokes. Specimens were analyzed using non-contact profilometry for dental volume loss (mm3) and lesion morphology. Data was analyzed using ANOVA with pairwise comparisons and Kruskal-Wallis tests. RESULTS: The two-way interaction between toothbrush head configuration and slurry abrasivity was significant (p = 0.02). At 35,000 strokes, the flat-trimmed and cross-angled/multilevel/rubbers added toothbrushes caused the highest loss, when associated to the high-abrasive slurry (p<0.05); whereas cross-angled/multilevel/flex head showed the least loss, when associated to the low-abrasive (p<0.05). At 65,000, more dental loss was observed for all toothbrushes when associated to the high-abrasive slurry, with flat-trimmed causing the highest loss (p < 0.05). Lower dental loss rates were observed for cross-angled/multilevel/flex head associated to the low-abrasive slurry when compared to the other toothbrushes (p < 0.05), except to feathered (p = 0.14) and rippled (p = 0.08). Flat lesions (mean internal angle ± standard-deviation: 146.2°± 16.8) were mainly associated with low-abrasive slurry, while wedge-shaped lesions (85.8°± 18.8) were more frequent with medium- and high-abrasive slurries. CONCLUSION: The development, progression and morphology of simulated NCCLs were modulated by both toothbrush head configuration and dentifrice abrasivity. CLINICAL SIGNIFICANCE: Dental professionals should consider both the type of toothbrush and dentifrice abrasivity in the management plan of patients at risk of developing NCCLs.

Investigating the etiology of non-carious cervical lesions: Novel µCT analysis.

OBJECTIVES: The etiology of non-carious cervical lesions (NCCLs) is not fully understood, limiting treatment and prevention. Our aim was to evaluate the effect of mechanical loading and acid exposure on the cervical tooth region using a random spectrum loading model that simulates the nature of oral mastication. METHODS: Thirty extracted human premolars were divided into three experimental groups: 1) unloaded teeth immersed in acid (erosion group: Er), 2) loaded teeth immersed in acid (erosion with spectrum loading group: Er-SL), and 3) loaded teeth immersed in distilled water (spectrum loading group: SL). Random spectrum loading with loads ranging from 100 to 500 N was performed. All teeth were scanned using micro-CT. A novel 3D analysis was developed to evaluate the circumferential cervical tissue loss and regions under tension and compression. For parametric and non-parametric comparisons, one-way ANOVA with Tukey post-hoc tests and Kruskal-Wallis with Bonferroni post-hoc tests were used. RESULTS: A significant difference was observed in the circumferential volumetric loss, with the Er-SL exhibiting the greatest volume loss (p < 0.001). Moreover, in the loaded groups (Er-SL and SL), regions subjected to tension showed significantly greater loss (p < 0.001, p = 0.007) compared with regions subjected to compression. CONCLUSIONS: The novel high-resolution micro-CT analysis provided new insights into the etiology of NCCLs. The results suggested that the cumulative effect of mechanical loading and acid exposure may play a major role in NCCL formation. CLINICAL SIGNIFICANCE: This study investigates the etiology of NCCLs by examining the combined effects of occlusal loads and acid exposure on cervical tissue loss. Understanding the pathogenesis of NCCLs paves the way for the development of improved preventative measures and treatment strategies to prevent tooth structure degradation.

Histologic and Electron Microscopic Characterization of a Human Immature Permanent Premolar with Chronic Apical Abscess 16 Years after Regenerative Endodontic Procedures.

Previous studies have reported successful clinical outcomes after regenerative endodontic procedures (REPs) for immature permanent teeth with pulpal infection. However, it remains unclear whether the procedures promote true regeneration or repair. This case report describes the histologic and electron microscopic characteristics of a human immature permanent premolar with a chronic apical abscess that was treated with an REP. Tooth #20 of a 9-year-old girl underwent an REP. At the 6-year follow-up, the patient was asymptomatic, and closure of the apex and thickening of the dentinal walls were observed. However, 16 years after the procedure, apical periodontitis recurred, necessitating apical surgery. The resected root fragments were obtained during the surgery and analyzed using micro-computed tomography, light microscopy, and scanning electron microscopy. Distinct dentinal tubules and interglobular dentin were observed in the regenerated hard tissue. Cementum-like tissue and a root canal were also observed in the apical fragment. The regenerated root tissue in this case exhibited a structure similar to the native root structure. Therefore, we believe that cell-free REPs possess regenerative potential for teeth diagnosed with pulp necrosis and chronic apical abscess.

Odontogenic keratocystic can be misdiagnosed for a lateral periodontal cyst when the clinical and radiographical findings are similar.

Lateral periodontal cyst (LPC) and odontogenic keratocystic (OK) are two osteolytic lesions of the jaw with different local invasiveness and percentage of recurrence. The aim of this study was to highlight the attention on the differential diagnosis of these lesions that sometimes can have unexpected location and can lead doubts on diagnosis, therapy, and follow-up. A 34-year-old man presented to our department with a complaint of soft pain in the vestibular aspect of left mandibular second premolar and left mandibular first molar. Vital teeth in the left mandible, no mucosal swelling, and no drainage were observed. The CBCT showed a well circumscribed hypodensity area, extending between 3.5 and the apex of mesial root of 3.6. No displacement and no resorption of the roots were notified. Upon clinical and radiographical examination, a provisional diagnosis of LPC was made and enucleation of the lesion and histological examination were planned. Histologically, a cystic wall partially lined by a keratinizing squamous epithelium was observed. Surrounding and within the lesion, there was a chronic inflammatory infiltrate also of granulomatous type and with cholesterol clefts. Based on these findings, the diagnosis of odontogenic keratocystic was done. Radiolucent lesions in the premolar and canine region are frequently clinically and radiographically misdiagnosed. The identification of keratocyst in a location preoperatively favoring a lateral periodontal cyst should be suspected and biopsy must be considered in all cases to establish the nature of the lesion, the best surgical treatment, and the follow-up appointments.

Ability of a Blue Hemoglobin-Based Liquid as a Novel Technology to Stain Initial Enamel Demineralization: A Proof-of-Concept in vitro Study.

During orthodontic treatment, enamel demineralization can occur. Its early detection is the basis for efficient preventive measures to arrest or remineralize lesions. In the present study, the application of a novel blue hemoglobin-based liquid (BlueCheck) was evaluated as proof of concept for detection of artificially demineralized smooth surfaces. 60 samples from extracted human posterior teeth were randomly assigned to four groups (15 per group). In 30 of these samples (groups A and B), superficial enamel was removed to create a ground surface. On the surface of other 30 samples (group C and D), orthodontic metal brackets were bonded. On each surface, BC liquid was applied and rinsed with water after 3 min (baseline). All surfaces were checked by two independent observers for presence of blue areas. On each sample, one side was covered by nail varnish to protect this enamel part from demineralization. The samples were demineralized with lactic acid (pH 4.6) for 7 days (group A and C) and 14 days (group B and D), respectively. Mineral loss was determined using quantitative light-induced fluorescence after demineralization. BlueCheck dye was again applied on the samples and evaluated for presence of stained areas. Histological sections were prepared from randomly selected samples and lesion depth was measured. Kruskal-Wallis test was used for group comparison (α = 0.05). After demineralization, median ΔF value for all samples was -8.25% indicating the presence of an initial demineralization. The difference of ΔF values was not statistically significant between samples at 7 or 14 days of demineralization, nor for samples with and without orthodontic brackets (p = 0.13). At baseline, none of the sample surfaces showed discoloration, whereas a distinctive blue color was visible after demineralization in all samples exposed to acid-exposed areas, corresponding to 100% sensitivity. The internal control surfaces (without demineralization) did not show any staining, corresponding to 100% specificity. Histologically measured lesion depths ranged between 200 and 254 µm. In this in vitro study, staining of demineralized enamel surface areas were shown to be reliable. Based on our results, this easily applicable product seems useful to be an adjuvant method to clinical examination to monitor oral health during an orthodontic treatment on tooth surfaces after removal of dental biofilm.

Detection of Cavitated Proximal Carious Lesions in Permanent Teeth: A Visual and Radiographic Assessment.

Detection of proximal carious lesions involves the combination of clinical and radiographic methods, both with inherent difficulties. The present cross-sectional study is aimed at estimating the prevalence of cavitation in proximal carious lesions, based on a direct clinical assessment of previously detected radiographic lesions, in permanent molars and premolars. Proximal dental surfaces were radiographically evaluated using the ADA coding system and cavitation was determined through clinical visual examination of the surfaces after separation with elastomeric bands. One-hundred and twenty-six patients attending the dental clinics at the University of Talca were examined, comprising 508 proximal surfaces with radiographic codes ranging from E1 to D3. Two examiners were trained and calibrated for radiographic and clinical detection of proximal lesions. Most participants were females (61.9%). The age mean of participants was 28.7 (0.8) years old. A total of 22.2% of the examined surfaces were cavitated. Only few lesions coded as E1 (n = 4; 2.1%) and E2 (n = 9; 9.8%) were cavitated. Fifty D1 (35.5%) and 22 D2 (41.5%) lesions were cavitated after separation. Most lesions coded as D3 (n = 28; 84.8%) were cavitated. The multilevel binary regression model (p = 0.003) demonstrated that sex, age, jaw, tooth type, surface, and side were not associated with the likelihood of having proximal cavitation. Challenging conventional wisdom, most D1 and D2 lesions were not cavitated. Combining detection methods seems desirable to increase the accuracy in assessing approximal posterior lesions. The low proportion of cavitated lesions reinforces the idea of cautiously indicating invasive approaches for managing proximal carious lesions.

Odontogenic Keratocyst Is Frequently Misdiagnosed for a Lateral Periodontal Cyst in Premolar and Anterior Tooth-Bearing Areas.

INTRODUCTION: Radiolucent lesions with gingival swelling found in the premolar and intercanine region can elicit a different clinical diagnosis than one confirmed by histologic findings. The purpose of the study is to identify and present the frequency of the unexpected microscopic diagnosis of odontogenic keratocyst (OKC) in a location preoperatively favoring a lateral periodontal cyst (LPC) with similar clinical and radiographic appearance. METHODS: A retrospective analysis of biopsies received from 2011 and 2019 was performed, and the number of LPC and OKC cases was assessed. The alignment of clinical and radiographic diagnosis to histologic findings and anatomic location was analyzed, and the number of OKC cases preoperatively misdiagnosed as LPCs was identified. RESULTS: A total of 79,257 biopsies were received. Of those, 184 were diagnosed as LPCs and 742 as OKCs. For all preoperatively diagnosed LPCs, the clinical and histologic diagnosis aligned; however, 182 of 742 OKCs were submitted with a clinical misdiagnosis of LPCs. The location of these lesions with the unanticipated diagnosis overlapped with those for LPCs, specifically the maxillary and mandibular anterior and premolar regions. CONCLUSIONS: Radiolucent lesions with gingival swelling in the premolar and intercanine region are frequently clinically and radiographically misdiagnosed. A biopsy should be considered in all cases to establish the correct pathologic diagnosis and treatment course.

The Effect of Partial Corticotomy on the Rate of Maxillary Canine Retraction: Clinical and Radiographic Study.

The study aimed to evaluate, clinically and radiographically, the effect of partial corticotomy of the buccal plate distal to the canine on the rate of maxillary canine retraction. A clinical trial with the split-mouth design was conducted among twenty orthodontic patients, recommended for first premolar extraction with an age range from 13 to 21 years, selected from patients seeking orthodontic treatment in private dental clinics in Jeddah, Kingdom of Saudi Arabia. After extraction of the maxillary right and left first premolar, partial corticotomy was performed distal to the canine on the right side. The canine retraction was carried out with a power chain on both sides extended between the canine and the maxillary first molar. The data collected from the current study were tabulated and statistically analyzed using an independent sample t-test with p < 0.05 considered statistically significant. The rate of canine retraction was significantly higher on the corticotomy side than the control side (p < 0.05). Under the limitations of the present study, it can be concluded that the technique of partial corticotomy of the buccal plate distal to the canine is a straightforward surgical procedure enhancing the rate of canine retraction significantly.

Preoperative Estimation of Endodontic Working Length with Cone-Beam Computed Tomography and Standardized Paralleling Technique in comparison to Its Real Length.

An accurate estimation of the working canal length is essential for successful root canal treatment. This study is aimed at investigating the diagnostic accuracy of root canal length estimation on cone-beam computed tomography (CBCT) scans and digital paralleling radiographs (PAs), using the real canal length as a gold standard, and at evaluating the influence of canal curvature on this estimation. Sixty extracted human premolar teeth were selected for this study. Root canal length measurement was performed on CBCT scans (NewTom, Giano, Verona, Italy) and digital paralleling radiography (EzRay Air W; Vatech, Korea). The real working length was established by subtracting 0.5 mm from the actual canal length. No significant difference was found between CBCT and digital paralleling radiography. There was a tendency for underestimation of the root canal length measured on the CBCT images in 52 (86.7%) of the examined teeth and overestimation in 5 teeth (8.3%). All the digital radiographs slightly overestimated the real canal length. The analysis revealed a strong correlation between the estimation from moderate to severe curvature for digital radiography and CBCT images. Preoperative working length estimation can be made closest to its real clinical canal length on the standardized paralleling technique, using a long (16-inch) target-receptor distance.

Functionalized Scaffold and Barrier Membrane with Anti-BMP-2 Monoclonal Antibodies for Alveolar Ridge Preservation in a Canine Model.

INTRODUCTION: The aim of this study was to investigate the ability of anti-bone morphogenetic protein 2 monoclonal antibody (anti-BMP-2 mAb) to functionalize scaffolds to mediate bone regeneration in a canine model. MATERIALS AND METHODS: The mandibular right premolar 4 (PM4) was extracted in eight beagle dogs and grafted with anti-BMP-2 mAb+anorganic bovine bone mineral with 10% collagen (ABBM-C) and porcine bilayer native collagen membrane (CM). The ABBM-C and CM were functionalized with either anti-BMP-2 mAb (test group) or an isotype matched control mAb (control group). Animals were euthanized at 12 weeks for radiographic, histologic, and histomorphometric analyses. Outcomes were compared between groups. RESULTS: 3D imaging using cone beam computed tomography (CBCT) revealed that sites treated with ABBM-C and CM functionalized with anti-BMP-2 mAb exhibited significantly more remaining bone width near the alveolar crest, as well as buccal bone height, compared with control groups. Histologic and histomorphometric analyses demonstrated that in anti-BMP-2 mAb-treated sites, total tissue volume was significantly higher in the coronal part of the alveolar bone crest compared with control sites. In anti-BMP-2 mAb-treated sites, bone formation was observed under the barrier membrane. CONCLUSION: Functionalization of the ABBM-C scaffold and CM appeared to have led to bone formation within healing alveolar bone sockets.

Prospective clinical study of transverse development with orthodontics with self-ligating brackets.

Orthodontics with low friction, low force, passive self-ligating brackets produces alveolar-dental remodeling, resulting in an increase in the transverse diameter of the dental arches, especially in the premolar sector. The aim of this study was to compare the modifications of the transverse diameter in the pre- and post-dental alignment cast models with orthodontics with passive self-ligating brackets in patients with moderate to severe dental discrepancy. The study included 28 patients of both sexes aged 16 to 48 years with dental discrepancies between -6 and -16 mm, treated with self-ligating Damon brackets and thermally activated Nickel- Titanium-Copper arches. With a digital pachymeter, Mitutoyo brand, five measurements were taken per dental arch: distance between canines (C), first premolars (1PM), second premolars (2 PM), first molars (1M) and second molars (2M), before and after orthodontic alignment. The variations were statistically evaluated by Student T Test for paired samples. Average distance between teeth varied with dental alignment in both jaws. The greatest increases in transverse diameter were recorded in the premolar areas. Minor though statistically significant variations also occurred in the 2M of the maxilla and in the C of the mandible In alignment with passive self-ligating brackets, there is an increase in the transverse diameter due to the development of the dental arches, mainly in the premolar sector of both jaws and also at the level of the canines in the mandible.

La ortodoncia con brackets autoligables pasivos, de baja fricción y baja fuerza, produce remodelación alvéolodentaria; con aumento del diámetro transversal de las arcadas, especialmente en el sector de los premolares. El objetivo de este trabajo fue comparar las modificaciones del diámetro transversal en los modelos de yeso pre y post alineación dentaria con ortodoncia con brackets autoligables pasivos en pacientes con discrepancia dentaria moderada a severa. El estudio incluyó 28 pacientes de ambos sexos de entre 16 y 48 años de edad con discrepancia dentaria entre -6 y -16mm, tratados con brackets autoligables sistema Damon y arcos termo activables de Níquel-Titanio-Cobre. Con un paquímetro digital marca Mitutoyo, se tomaron 5 medidas por arcada: distancia entre caninos (C), primeros y segundos premolares (1 PM y 2 PM) y primeros y segundos molares (1M y 2M); pre y post alineación ortodóncica. Las variaciones registradas fueron evaluadas estadísticamente mediante Student T Test para muestras apareadas. La distancia promedio entre dientes varió con la alineación dentaria en ambos maxilares. Los mayores aumentos del diámetro transversal se registraron en las zonas de los premolares. Se produjeron también variaciones menores, aunque estadísticamente significativas, en los 2M del maxilar superior y en los C del maxilar inferior. En la alineación con brackets autoligables pasivos, hay incremento del diámetro transversal por desarrollo de las arcadas, principalmente en el sector premolar de ambos maxilares y en el maxilar inferior también a nivel de los caninos.

Prospective clinical study of transverse development with orthodontics with self-ligating brackets / Estudio clínico prospectivo del desarrollo transversal con ortodoncia con brackets autoligables

ABSTRACT Orthodontics with low friction, low force, passive self-ligating brackets produces alveolar-dental remodeling, resulting in an increase in the transverse diameter of the dental arches, especially in the premolar sector. The aim of this study was to compare the modifications of the transverse diameter in the pre- and post-dental alignment cast models with orthodontics with passive self-ligating brackets in patients with moderate to severe dental discrepancy. The study included 28 patients of both sexes aged 16 to 48 years with dental discrepancies between -6 and -16 mm, treated with self-ligating Damon brackets and thermally activated Nickel- Titanium-Copper arches. With a digital pachymeter, Mitutoyo brand, five measurements were taken per dental arch: distance between canines (C), first premolars (1PM), second premolars (2 PM), first molars (1M) and second molars (2M), before and after orthodontic alignment. The variations were statistically evaluated by Student T Test for paired samples. Average distance between teeth varied with dental alignment in both jaws. The greatest increases in transverse diameter were recorded in the premolar areas. Minor though statistically significant variations also occurred in the 2M of the maxilla and in the C of the mandible In alignment with passive self-ligating brackets, there is an increase in the transverse diameter due to the development of the dental arches, mainly in the premolar sector of both jaws and also at the level of the canines in the mandible.

RESUMEN La ortodoncia con brackets autoligables pasivos, de baja fricción y baja fuerza, produce remodelación alvéolodentaria; con aumento del diámetro transversal de las arcadas, especialmente en el sector de los premolares. El objetivo de este trabajo fue comparar las modificaciones del diámetro transversal en los modelos de yeso pre y post alineación dentaria con ortodoncia con brackets autoligables pasivos en pacientes con discrepancia dentaria moderada a severa. El estudio incluyó 28 pacientes de ambos sexos de entre 16 y 48 años de edad con discrepancia dentaria entre -6 y -16mm, tratados con brackets autoligables sistema Damon y arcos termo activables de Níquel-Titanio-Cobre. Con un paquímetro digital marca Mitutoyo, se tomaron 5 medidas por arcada: distancia entre caninos (C), primeros y segundos premolares (1 PM y 2 PM) y primeros y segundos molares (1M y 2M); pre y post alineación ortodóncica. Las variaciones registradas fueron evaluadas estadísticamente mediante Student T Test para muestras apareadas. La distancia promedio entre dientes varió con la alineación dentaria en ambos maxilares. Los mayores aumentos del diámetro transversal se registraron en las zonas de los premolares. Se produjeron también variaciones menores, aunque estadísticamente significativas, en los 2M del maxilar superior y en los C del maxilar inferior. En la alineación con brackets autoligables pasivos, hay incremento del diámetro transversal por desarrollo de las arcadas, principalmente en el sector premolar de ambos maxilares y en el maxilar inferior también a nivel de los caninos.

Influence of cavity depth and restoration of non-carious cervical root lesions on strain distribution from various loading sites.

BACKGROUND: We aimed to investigate the load-induced strain variation in teeth with unrestored and resin-based composite restored non-carious cervical lesions (NCCLs). METHODS: Twelve extracted premolars were provided for measuring buccal-side root NCCLs. Strain gauges were fixed at four measuring sites of each tooth, two at the buccal surface and two at the lingual surface. NCCLs were prepared with occlusal margins at the cemento-enamel junction. A static 9-kg load was applied at seven occlusal loading points: buccal cusp tip (BC), inner inclination of the BC, lingual cusp tip (LC), inner inclination of the LC, center of the mesial marginal ridge or distal marginal ridge, and center of the central groove. The strain was detected at each site in teeth with NCCL depths of 0 (control), 0.5, 1.0, and 1.5 mm. Each NCCL was restored using an adhesive composite resin, and the strains were re-measured. RESULTS: The strains at the NCCL occlusal and gingival margins decreased with increasing defect depths, and the effect was significant when the depth of the defect was 1.5 mm. Loading on the buccal and lingual cusps induced prominent strain variation. The strains at all depth distribution recovered to nearly intact conditions when the NCCLs were restored. CONCLUSIONS: NCCLs at 1.5 mm depth are detrimental, but they can be restored using resin composites. CLINICAL SIGNIFICANCE: The existence of NCCLs should not be ignored. The depth of the NCCL may affect the progression of the lesion. Resin composite restoration is an appropriate method for preventing persistent NCCL deterioration.

Inter-premolar width changes related to the orthodontic traction of maxillary impacted canines in adolescents and young adults: A retrospective CBCT study.

OBJECTIVE: Maxillary canine impaction is directly associated with a narrow maxillary arch, mainly in the inter-premolar widths. This study compared the transverse changes at the level of maxillary premolars after traction of maxillary impacted canines (MICs) in adolescents and young adults through three main goals: to compare unilateral versus bilateral cases, to compare buccally versus palatally MIC cases, and to compare the affected versus non-affected side exclusively in the unilateral group. METHODS: This before and after CBCT study involved 45 MIC orthodontically tractioned until the occlusal plane with a standardized protocol. The sample was classified regarding the impaction type (unilateral versus bilateral), impaction location (palatal versus buccal) and the affected versus unaffected sides in the unilateral cases. MIC characteristics as impaction sector, height, and complexity of the traction, as well as α and ß angles, canine root length and area were measured. Moreover, cephalometric characteristics were also evaluated. Mann-Whitney U or Wilcoxon signed-rank tests and multiple regressions were applied (α=0.05). RESULTS: Maxillary inter-premolar widths (first or second) expanded approximately 3mm after traction of unilateral or bilateral MIC (P>0.05). Changes in hemi-arch widths between palatal (1.67mm) versus buccal (1.90mm) MIC were similar (P>0.05). In unilateral impaction, the transversal changes on the affected side were 2mm versus almost 1mm observed in the unaffected side (P<0.05). Finally, the multiple linear regressions were identified to the ANB angle, the impaction sectors and the distance from middle raphe to the cusp tip of MIC as influential variables. CONCLUSION: The maxillary inter-premolar widths increase after traction of MIC without differences between type or location of impaction. In addition, the transverse change in the affected side in unilateral MIC is greater than the unaffected side resolving the earlier transverse asymmetry.

Comparison of stress distribution in partially and completely edentulous mandibles around splinted and non-splinted implant prostheses: A finite element study.

BACKGROUND: In some treatments using multiple dental implants, the implants are inserted in the bone with splinted or non-splinted implant prostheses. There are some reports about the influence of the splinted and non-splinted implants on stress distribution in the bone using the finite element method (FEM), and there is a controversy in the literature regarding whether the splinted or non-splinted implants prostheses reduce the stress generated on the implant-surrounding bone more efficiently. Additionally, the simple shape of the jaw bones with limited bone area was used for FEM analysis in many studies at the expense of accurate analysis. OBJECTIVE: The aim of this study was to evaluate the difference in stress distribution in the bone between the splinted and non-splinted implants, and between completely and partially edentulous mandibles. METHODS: The implants were inserted in the first premolar, second premolar, and first molar regions of the partial and complete mandibles, and the splinted and non-splinted crowns were attached to the implants. Vertical load (100 N) or oblique load (70 N, 30° from its long axis towards the lingual) was applied on the first premolar. RESULTS: When vertical load was applied to the partially edentulous mandible model, the stress was concentrated intensively on the cortical bone around the first premolar regardless of whether splinted or non-splinted implants were used. On the other hand, the vertical load applied to the completely edentulous mandible model caused the stress to be concentrated intensively on the cortical bone around the first premolar with non-splinted implants. With respect to the oblique load, the stress was concentrated intensively on the cortical bone around the first premolar only with the non-splinted implants, in both the partial and complete mandibles. CONCLUSION: This study shows the different stress distributions of the cortical bone around the implants between the partial and complete mandible. This indicates that the complete mandible should be used for the analysis of bone stress distribution around the implants using FEM.

Stereomicroscopic and Microscopic Study of Dental Structural Aspects Derived from Iatrogenic and Pathological Processes Suffered by a Second Mandibular Premolar - A Case Study.

Microscopic studies performed on extracted human teeth after their preparation in advance is helpful in a relatively good reestablishment of the treatment steps that have been applied to these teeth, as well as an evaluation of the quality of such treatments. Therefore, we have used stereo- and optical microscopy, highlighting aspects of external morphology, as well as root canal space of an extracted mandibular second premolar, subjected to prosthetic and endodontic treatment. In order to verify some technical errors that might occur during the endodontic and restorative treatment, we tried to appreciate the quality of the root canal filling and cervical defect and access cavity restoration of an extracted premolar #45.Without having the data from clinical records, we concluded that the method used for root canal filling was the warm lateral condensation technic; we also appreciated the quality of the fusion of the gutta-percha cones used, so the introduction of heated spreaders only in the central part of the bunch of cones makes it possible to clearly detect the boundaries between these cones towards the outside of the filling.

Microfiltración apical entre dos cementos de obturación: biocerámico y resinoso en premolares unirradiculares preparadas con protaper, y obturadas con condensación lateral / Apical microfiltration between two filling cements: bioceramic and resinous in unirradicular premolars prepared with protaper and sealed with lateral condensation

Resumen Objetivo: Comparar in vitro la microfiltración apical en premolares unirradiculares obturados con cemento a base de resina epóxica y cemento biocerámico. Método: 40 piezas dentales unirradiculares fueron seleccionadas y divididas en dos grupos para ser obturadas esperando el tiempo de fraguado de acuerdo con las instrucciones del fabricante. El grupo A se obturó con cemento biocerámico Endosequence y, el grupo B, con cemento a base de resina epóxica AH-Plus: posteriormente los dos grupos fueron sellados con barniz de uñas hasta 3mm de la parte apical, luego se colocaron las muestras en la incubadora a 37ºC. Ambos fueron sometidos a 750 ciclos de termociclado, para reproducir el ambiente parecido a la cavidad oral. Para análisis de microfiltración se utilizó el método de difusión del colorante, se sumergieron en azul de metileno al 2 % por 6 días, posteriormente los especímenes fueron sometidos en una bomba de vacío. Los dientes fueron cortados longitudinalmente para ser evaluadas mediante el estereomicroscopio. El análisis estadístico fue hecho mediante T-Student y Chi-Cuadrado. Resultados: El grupo A corresponde a Endosequence obtuvo una medida de 0,55mm y el grupo B corresponde a AH-Plus 1,20mm con un estimado de significancia de p=0,013. Conclusión: El análisis de ambos cementos de obturación demostró que Endosequence posee menor microfiltración apical que AH-Plus.

Abstract Aim: To compare in vitro by the stereomiscroscope the lesser apical microfiltration in uniradicular premolars, between the cement based on Epoxy Resin and Bioceramic cement. Method: The study was performed on 40 uniradicular dental pieces divided into two groups, the samples were prepared using the protaper system and the obturation was performed using the lateral condensation technique, the first group was sealed withEndosequence bioceramic cement and the second group with Cement based on AH-Plus epoxy resin, then sealed with nail varnish up to 3mm from the apical part, then the samples were placed in the incubator at 37ºC, waiting for the set time corresponding to each group according to the manufacturer's instructions . The two groups of the present study were submitted to 750 cycles of thermocycling, to provide an environment similar to the oral cavity, then longitudinal cuts were made to the samples. The microfiltration was evaluated using the dye diffusion method, immersed in 2% methylene blue for 6 days, then the specimens were subjected to a vacuum pump. The teeth were cut longitudinally to be evaluated by the stereomicroscope. The statistical analysis was through T-Student and Chi-Square. Results: Group A corresponds to Endosequence obtained a mean of 0,55mm and Group B corresponds to AH-Plus 1,20mm with an estimated significance of p = 0,013. Conclusion: Both obturation cements have significant differences, therefore Endosequence has less apical microfiltration than AHPlus.