Comparison Between Radiographs, White and Fluorescent Images in the Diagnosis and Treatment Decisions for Occlusal Caries: An Ex Vivo Study

ABSTRACT Objective: To compare the agreement of images in white light (WL), fluorescence (FL), and digital radiographs (DR), on the diagnosis and treatment decisions for occlusal caries lesions against a micro-CT gold standard. Material and Methods: Ten extracted third molars, with enamel and/or dentin caries (ICDAS 2-4), were included. Occlusal surface images were acquired with an intraoral camera (SoproLife®) in WL and FL modes. DR was obtained using an intraoral X-ray and a semi-direct digital system. A total of 780 images were needed, organized in a template, to be later examined by twenty-six dentists invited to compose the study. The Generalized Estimation Equations model was used to compare the proportions of the correct answers between the three methods and the gold standard. When significant, Bonferroni post-hoc test was used to identify differences (α=5%). Results: Most of the examiners were specialists (76.9%) with 14.5 years of experience. All diagnostic methods were similar and showed low agreement (DR 12.7%, WL 16.5%, and FL 16.5%) compared with gold standard caries diagnostic scores. Regarding treatment decisions, mean agreement for all diagnostic methods was higher (43.2%; p<0.001), and among all methods, WL (48.1%) and FL (51.2%) modes performed better than DR (30.4%, p<0.001). Conclusion: SoproLife® images could help clinicians to propose rational, minimally invasive treatments for occlusal caries lesions.

Validación del instrumento para determinación de prevalencia de celulitis facial y su relación con la caries dental en pacientes de 5 a 9 años de edad / Validation of the instrument for the determination of prevalence of facial cellulite and its relationship with cariesdental in patients from 5 to 9 years of age

La celulitis facial odontogénica es comúnmente observada en las salas de emergencia hospitalarias en los pacientes pediátricos debido a la caries dental. Objetivo: Validar el instrumento de prevalencia de celulitis facial y su relación con la caries dental en pacientes de 5 a 9 años de edad en el Hospital General IESS Milagro. Materiales y métodos: Enfoque mixto cuantitativa y cualitativa, tipo de investigación de campo, corte transversal, descriptivo, no experimental, se realizó un plan piloto de 15 pacientes pediátricos, un instrumento cuantitativo (Ficha de recolección de datos) contó con 9 expertos para un juicio de expertos y en el instrumento cualitativo (Entrevista) contó con 6 expertos para la validación del instrumento en total son de 15 profesionales en salud, calificando Validez, Pertinencia y Coherencia. Resultados: El instrumento cuantitativo tiene una puntuación de 80,85 de confiablidad y el instrumento cualitativo tiene una puntuación de 87,11 de confiablidad. En el instrumento cuantitativo se determinó la prevalencia de celulitis facial de niños de 5 a 9 años de edad, género masculino (80%), rango de 7 a 8 años (53,3%), cita por primera vez (60%), antecedente referencial caries dental (93,3%), diagnóstico CIES10 fue el L032 celulitis de la cara (93,3%), región afectada en la zona submandibular (73,3%), prevalencia de caries dental, molares deciduos (93,3%), no registran antecedentes de buena salud (73,3%), tratamientos odontológicos de prevención al año ninguna (80%), causa frecuente en la aparición de celulitis facial, la necrosis pulpar K041. Conclusión: La validación del instrumento tuvo un grado de confiabilidad muy buena y su cifra de alfa de Cronbach alto, la misma que da seguridad y confianza, gracias a la calificación de los jueces que revisaron cada detalle(AU)

Odontogenic facial cellulite is commonly observed in hospital emergency rooms in pediatric patients due to the dental caries. Objective: to validate the facial cellulite prevalence instrument and its relationship with dental caries in patients from 5 to 9 years of age in the IESS Miracle General Hospital. Materials and methods: mixed approach quantitative and qualitative, type of field research, cross section, descriptive, non-experimental, a pilot plan of 15 patients was carried out ediatric patients, a quantitative instrument (data collection form) counted with 9 experts for an expert judgment and in the qualitative instrument (Interview) had 6 experts for the validation of the instrument in total they are of 15 health professionals, qualifying Validity, Relevance and Coherence. Results: the quantitative instrument has a score of 80.85 of reliability and the qualitative instrument has a score of 87.11 out of reliability. In the quantitative instrument, the prevalence of facial cellulite in children 5 to 9 years of age, male gender (80%), range 7 to 8 years old (53.3%), appointment for the first time (60%), referential history dental caries (93.3%), CIES10 diagnosis was L032 facial cellulite (93.3%), affected region in the submandibular area (73.3%), prevalence of dental caries, deciduous molars (93.3%), do not record a history of good health (73.3%), preventive dental treatments per year none (80%), frequent cause in the appearance of facial cellulitis, pulpal necrosis K041. Conclusion: the validation of the instrument had a very high degree of reliability. good and its high Cronbach's alpha figure, the same one that gives security and confidence, thanks to the rating of the judges who reviewed every detail(AU)

Effectiveness of Low-Level Laser Therapy with a 915 Nm Wavelength Diode Laser on the Healing of Intraoral Mucosal Wound: An Animal Study and a Double-Blind Randomized Clinical Trial.

Background and objectives: Diode laser has been the most popular low-level laser therapy (LLLT) technique in dentistry due to its good tissue penetration, lower financial costs, small size for portable application, and convenience to use. A series of recent studies with 940 nm or 980 nm lasers demonstrated that LLLT showed positive effects after third molar extraction or periodontal flap surgery. However, the effects of LLLT on intraoral mucosal wound healing after surgical incision have not yet been determined in human clinical study. Materials and Methods: The present study was performed to determine the efficacy and safety of 915 nm wavelength low-level laser therapy (LLLT) in mucosal wound healing. A total of 108 Sprague-Dawley rats were used. They were divided into three groups: Abrasive wound group, immediate LLLT once group, and daily LLLT group. As a clinical study, a total of 16 patients with split-mouth design subjected to bilateral mandibular third molar extraction were allocated into the LLLT group and placebo group. The process of LLLT was performed on postoperative days 0, 1, and 7, and parameters related to wound healing were analyzed on days 1, 7, and 14. Results: Repeated laser irradiation promoted mucosal wound healing of the rats. In the clinical study, although there were no significant statistical differences between the LLLT and placebo groups in all inflammatory parameters, the early stage mucosal healing tendency of wound dehiscence was higher in the LLLT group than in the placebo group clinically on postoperative day 1. Conclusions: The present results showed that 915 nm LLLT could be applied safely as an auxiliary therapy for mucosal wound healing.

Relationship between the Position of Impacted Third Molars and External Root Resorption of Adjacent Second Molars: A Retrospective CBCT Study.

BACKGROUND AND OBJECTIVES: Impacted third molars (ITM) are the most commonly-impacted teeth. There is a risk for ITM to cause a number of pathological conditions, and external root resorption (ERR) of adjacent teeth is one of the most prevalent. Retaining or prophylactic extraction of ITM is a polemic topic. External root resorption of adjacent teeth is one of possible indications for prophylactic removal of ITM. The aim of this study was to assess the relationship between external root resorption (ERR) on the distal aspect of second molars' roots and positional parameters of ITM. Methods: Cone beam computed tomography scans of 109 patients (41 males, 68 females; mean age 26.4 ± 7.9 years) with 254 ITM (131 in the maxilla and 123 in the mandible) were retrospectively analyzed. Positional parameters of ITM (mesio-distal position, angulation, impaction depth, and available eruption space) were evaluated. The presence, location, and depth of ERR of adjacent second molars were assessed. Results: Analysis showed a relationship between ITM impaction depth, mesial inclination angle, and the presence of ERR. Mesial inclination angle of more than 13.6° increased the odds of ERR occurrence by 5.439 (95% CI, 2.97-9.98). ITM presence at the level of ½ of roots of the adjacent second molar or more apically increased the odds of ERR occurrence by 2.218 (95% CI, 1.215-4.048). No significant correlation was detected between the occurrence of ERR and patient age, gender, or the available eruption space in the mandible. Depth of ERR did not depend on its location. Conclusions: Incidence of ERR in second molars is significantly associated with mesial inclination and a deep position of ITM.

Prevalence of impacted mandibular third molars and its association with distal caries in mandibular second molars using cone beam computed tomography / Prevalencia de terceros molares mandibulares impactados y su asociación con caries distales en segundos molares mandibulares mediante tomografía computarizada de haz cónico

This study evaluated the prevalence and eruption's pattern of impacted mandibular third molars (IMTM) and the influence of their eruption status on the distal caries of mandibular second molars (MSM) using cone-beam computed tomography (CBCT). Material and methods: CBCT images taken for different purposes in private dental practices were analyzed retrospectively. Radiographic assessment included: prevalence of IMTM, degree of angulation, level of impaction and type of IMTM. Furthermore, the distance between the cement-enamel junctions (CEJ) of second and third molars and the occurrence of caries lesion on the distal surface of MSM was also evaluated. Data were analyzed by chi square test and logistic regression was used to find the association between distal caries of MSM and eruption status of IMTM. Results: Three hundred and eight CBCTs were screened, the prevalence of IMTM was 36.88% and their angulation degree were mostly less than 90º (mesioangular). Amongst those with impaction, 58 subjects (43%) had distal caries on MSM, 29.6% in females and 30.4% in the age group 19-27 years. Caries on the distal side of MSM were significantly associated with age, level and type of impaction, angulation degree and CEJ distances (p<0.05). Conclusions: The prevalence of IMTM is high (36.88%) and there are significant relationships between angulation degree, level and type of impaction, and CEJ distances with caries on the distal side of MSM.

Introducción: Este estudio evaluó la prevalencia y el patrón de erupción de terceros molares mandibulares impactados (TMMI), y la influencia de su estado de erupción en la caries distal de los segundos molares mandibulares (SMM) mediante tomografía computarizada de haz cónico (TCHC). Material y métodos: se analizaron retrospectivamente las imágenes de TCHC tomadas para diferentes fines en prácticas dentales privadas. La evaluación radiográfica incluyó: prevalencia de TMMI, grado de angulación, nivel de impacto y tipo de TMMI. Además, también se evaluó la distancia entre la unión amelocementaria (UAC) de los segundos y terceros molares y la aparición de lesión de caries en la superficie distal de SMM. Los datos se analizaron mediante la prueba de chi cuadrado y se usó la regresión logística para evaluar asociaciones entre la caries distal de SMM y el estado de erupción de TMMI. Resultados: Se examinaron 308 TCHC, la prevalencia de TMMI fue de 36.88% y su grado de angulación fue mayoritariamente menor a 90º (mesioangular). Entre aquellos con impacto, 58 sujetos (43%) tenían caries distales en los SMM, 29.6% eran mujeres y 30.4% pertenecieron al grupo de edad de 19-27 años. Las caries en el lado distal de MSM se asociaron significativamente con la edad, el nivel y el tipo de impactación, el grado de angulación y las distancias UAC (p<0.05). Conclusiones: la prevalencia de TMMI es alta (36.88%) y existen relaciones significativas entre el grado de angulación, el nivel y el tipo de impacto, y las distancias UAC con presencia de caries en el lado distal de los SMM.

Regeneración ósea en alvéolos dentarios de terceros molares mandibulares empleando plasma rico en plaquetas en pacientes fumadores / Bone regeneration in mandibular third molar dental sockets of smokers using platelet rich plasma

Objetivo. El propósito del trabajo fue evaluar la regeneración ósea en alvéolos dentarios empleando como coadyuvante PRP en pacientes fumadores. Materiales y método. Estudio de intervención cuasiexperimental; se asignaron 2 grupos de estudio, uno experimental y otro de control; se realizó exodoncia a los 2 grupos de los dientes 38 y 48. Al grupo control no se aplicó PRP y al experimental se le aplicó PRP con el método de una centrifugación en el alvéolo del diente 38 y PRP con doble centrifugación en alvéolo del diente 48; se realizaron controles radiográficos a los 8, 30 y 60 días después de la cirugía para evaluar la densidad ósea. Se realizó análisis estadístico descriptivo univariado, bivariado y prueba t de Student. Resultados. Hicieron parte del estudio 19 sujetos, el 52,6% de ellos fueron de sexo masculino, al estudiar la densidad ósea en los 3 controles radiográficos del grupo experimental en el alvéolo del diente 38 y 48, no se encontraron diferencias estadísticamente significativas (p > 0,05), pero sí una leve mejoría en la cicatrización del alvéolo 48 donde se empleó PRP con el método de doble centrifugación. Al comparar los controles radiográficos del grupo control con los del grupo experimental se encontraron valores estadísticamente significativos en el grupo que se le aplicó PRP con el método de una o doble centrifugación (p<0,05). Conclusión. El proceso de regeneración ósea es más favorable en los pacientes fumadores que se les aplica PRP que en aquellos que no se les aplica. No se observó una diferencia estadísticamente significativa en el proceso de regeneración ósea aplicando PRP con el método de una y doble centrifugación

Objective. The aim of this study was to evaluate bone regeneration in the dental sockets of smokers using platelet-rich-plasma (PRP) as an adjuvant. Materials and method. A quasi-experimental intervention study of two groups (experimental and control) in whom teeth number 38 and 48 were extracted. PRP was not applied in the control group, but it was applied in the experimental group using the single centrifugation method in the socket of tooth 38, and with double-centrifugation PRP being applied in the socket of tooth 48. Radiography follow-up was performed at 8, 30, and 60 days after the surgery in order to evaluate the bone density. A univariate and bivariate descriptive analysis and Student-t test were performed. Results. Of the 19 subjects that took part in the study, 52.6% were male. In the bone density study using the three radiographic controls at 8, 30, and 60 days, no statistically significant differences (P>.05) were found in the experimental group in the sockets of tooth 38 and 48, but there was a slight improvement in the healing of socket 48 where PRP was used with the method of double centrifugation. On comparing the follow-up x-rays of the control with those of the experimental group, statistically significant values were found in the group where PRP was applied using the single or double centrifugation method (P<.05). Conclusions. The bone regeneration process is more favourable in those smokers on whom PRP was applied than in those where it was not applied. No statistically significant difference was observed in the bone regeneration process applying PRP using the single or double centrifugation method

Influence of Bristle Stiffness of Manual Toothbrushes on Eroded and Sound Human Dentin--An In Vitro Study.

AIM: The aim of this study was to determine the influence of manual toothbrushes with different bristle stiffness on the abrasivity on eroded and sound human dentin. MATERIALS AND METHODS: Dentin specimens were made from impacted third molars and attributed to three groups: erosion-abrasion (EA), abrasion (A) and erosion (E). The specimens from EA and E were treated with 1% citric acid (pH 2.3) for 1 min rinsed, and neutralized with artificial saliva for 15 min. This cycle was repeated five times. Thereafter, specimens from EA and A were treated with three toothbrushes types with different bristle stiffness (soft, medium, and hard) in a custom-made toothbrushing machine. The brushing was performed at a load of 3 N with a toothpaste slurry for 630 s. This procedure was repeated five times, in group EA after each erosion cycle. EA and A groups passed through five cycles with a total of 6300 strokes. The abrasivity was analyzed by contact-free profilometry. Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis. RESULTS: With respect to bristle stiffness there was no statistically significant difference in dentin loss within the EA group. In group A, a statistically significantly higher dentin loss was found for the soft in comparison to the hard bristles. No statistically significant differences were measured between soft/medium and medium/hard toothbrushes. The amount of dentin loss from specimens in the EA group was significantly higher than in the A group. CONCLUSIONS: Within the limitations of this study, the dentin loss in the Abrasion group was higher with soft bristles than with hard ones. This result might have an influence on the toothbrush recommendations for patients with non-carious cervical lesions.

Removal of Long-Term Broken Roots Displaced Into the Maxillary Sinus by Endoscopic Assistant.

PURPOSE: This report presented a patient with 2 long-term broken roots displaced in left maxillary sinus. The residual root fragments made the patient uncomfortable in both mind and body and interfered with prosthodontics work. The application of endoscope combined with piezoelectric device both helps in removing the broken roots successfully with minimally surgical injury and preserves the residual alveolar bone. METHODS: Computed tomography scans and 3-dimensional reconstructions located the broken roots. A 1.0 cm × 1.5  cm rectangle bone window on anterolateral sinus wall was opened by a piezoelectric device to place the endoscope and forcep into sinus. Two broken roots could be observed clearly via a endoscopic screen. They were removed by a mini goblet forcep completely and efficiently. A whole bone lid was replaced with a biological membrane to help repair bone defect after removing procedure. RESULTS: The operation is about 20 minutes with endoscope and piezoelectric device helped to save a lot of time and provided excellent visual surgical field. Main postoperative adverse effects were swelling, numbness, and temporal no-vitality for the first premolar (24). Three months later, computed tomography shows the Schneiderian membrane thinned to around 0.8  mm. The bone lid is on its position and starts to perform synostosis. The 24 tooth is still dysesthetic and needs time to recover. CONCLUSIONS: Endoscopic surgery combined with a piezoelectric device has obvious advantage of minimizing surgical injury and providing excellent visibility of surgical field when removing long-term foreign bodies in maxillary sinus. It is efficient and protects the residual alveolar bone.

Associação entre o tempo cirúrgico e infecção pós-operatória na exodontia de terceiros molares / Association between surgical time and postoperative infection in third molar surgery

Introdução: Os quadros de infecção constituem a principal complicação associada a exodontia de terceiros molares. Apesar da baixa incidência, em torno de 10%, tendo em vista o grande número de procedimentos realizados em todo o mundo, o número absoluto de casos de infecção também tende a ser elevado. Apesar disso, o uso rotineiro de antibiótico profilático tem sido questionado em função da sua eficácia, efeitos colaterais, custo e principalmente pela crescente emergência de microorganismos resistentes. Na tentativa de racionalizar o uso de antibióticos, diversos trabalhos tem procurado estimar o risco de infecção baseado em aspectos relacionados ao paciente, ao procedimento cirúrgico e às características anatômicas e radiográficos do dente porém, tendo em vista o grande número de variáveis envolvidas e à forte interação entre elas, não se conseguiu, ainda, um modelo capaz de ponderar de forma confiável e reprodutível todas essas variáveis. Supondo que o tempo cirúrgico possa fazer essa ponderação, o objetivo deste estudo foi tentar correlacionar o tempo cirúrgico

e o índice de infecção pós-operatória na exodontia de terceiros molares. Material e métodos: Foram realizadas 349 cirurgias em 197 pacientes saudáveis com indicação de exodontia de ao menos um terceiro molar. Todos os pacientes foram operados com a mesma técnica cirúrgica e dose única de antibiótico pré-operatório. A variável primária do estudo foi o tempo cirúrgico e o desfecho a presença ou ausência de infecção de acordo com os parâmetros clínicos definidos pelo "Center for Disease Control" (CDC). Também foram avaliados a interação entre idade, gênero, posição do dente e experiência do cirurgião com o tempo cirúrgico. Resultados: A incidência de infecção foi de 4,6% e houve uma clara associação entre tempo cirúrgico e infecção, inclusive na análise multivariada (OR=1,017, IC95% =[ 1,001; 1,034 ], p=0,043), sendo que todos os casos infectados tiveram tempo cirúrgico superior a 30 minutos. Conclusões: O tempo cirúrgico pode ser usado como indicador de risco para infecção na exodontia de terceiros molares podendo definir a conduta de antibioticoterapia pós-operatória.

Introduction: Postoperative infection is the most common complication associated with third molar extraction. Despite the low incidence, around 10%, considering the large number of surgerys performed around the world, the absolute number of postoperative infections also tends to be high. Nevertheless, the routine use of prophylactic antibiotics is controversy, due to its side effects, cost, and mainly by the increasing emergence of resistant microorganisms. In attempt to rationalize antibiotics prescription, several studies have tried to estimate the postoperative infection risk based on patient related aspects, surgical procedure and tooth anatomical and radiographic characteristics but with little succsess, because of the large number of variables involved and their strong interaction. The aim of this study is to correlate the surgical procedure time and the postoperative infection rate in third molar surgery. Methods: We performed 349 surgeries in 197 healthy

patients with at least one third molar to be removed. All patients were operated with the same surgical technique and single-dose preoperative antibiotic. The primary variable was the surgical time and the outcome, the presence or absence of infection according to the clinical parameters defined by the "Center for Disease Control" (CDC). We also assessed patients age, gender, tooth posítion and surgeon experience. Results: The incidence of infection was 4.6% and there was a clear association between operative time and infection, even in the multivariate analysis (OR = 1.017, 95% CI = [1.001, 1.034], p = 0.043), and all infected cases had surgeries lasting more than 30 minutes. Conclusions: Operating time can be used as an risk indicator for infection in third molar surgery and thus can define the postoperative antibiotic therapy.

UVA-activated riboflavin improves the strength of human dentin.

The aim of this study was to evaluate the effects of UVA-activated riboflavin (UVA-RF) on the mechanical properties of non-demineralized human dentin. Dentin specimens obtained from 20 teeth were randomly divided into the following four groups: group 1 (control): no treatment, group 2 (low UVA-RF): specimens were exposed to UVA-RF for 10 min, group 3 (medium UVA-RF): specimens were exposed to UVA-RF for 30 min, and group 4 (high UVA-RF): specimens were exposed to UVA-RF for 60 min. Three-point flexural test and Raman spectroscopic analyses were performed. The mean flexural strengths (MPa) were 129.96, 128.96, 144.21, and 147.54, and the mean elastic modulus (GPa) were 8.59, 8.38, 10.21, and 9.87 for groups 1 to 4, respectively. Raman spectra showed chemical modifications of dental collagen under medium and high UVA-RF treatment. We conclude that medium and high UVA-RF increases the strength of non-demineralized human dentin by collagen crosslinking.

Detección de microorganismos anaerobios en pacientes con pericoronaritis y sensibilidad a los antimicrobianos / Anaerobic microorganisms detection in patients with pericoronaritis and antimicrobial susceptibility

El propósito de este estudio fue la identificación de microorganismos anaerobios más frecuentemente encontrados en pericoronaritis y realizar pruebas de sensibilidad a los antimicrobianos. Se estudiaron los sacos pericoronarios del tercer molar en 20 pacientes. De las muestras recogidas en los 20 pacientes que presentaron pericoronaritis, solo en 7 (35%) hubo crecimiento de microorganismos anaerobios estrictos mientras que en los 13 restantes (65%) no se detectaron estos. En cuanto a las 12 cepas aisladas del saco pericoronario de los 7 pacientes, el microorganismo más frecuentemente encontrado fue Bifidobacterium spp en 5 casos (42%), Bifidobacterium adolescentis en 2 casos (17%), Veillonella spp en dos casos también (17%), Prevotella melaninogenica en 1 caso (8%), 1 caso Prevotella loescheii (8%) y en 1 caso a Prevotella oralis (8%). De los resultados obtenidos las bacterias anaerobias estrictas detectadas a partir de muestras de sacos pericoronarios fueron: Bifidobacterium spp., B. adolescentis, Veillonella spp, P. loeschii, P. melaninogenica y P. oralis.

Determination of fracture toughness of human permanent and primary enamel using an indentation microfracture method.

The purpose of the present study was to examine the fracture toughness and Vickers microhardness number of permanent and primary human enamel using the indentation microfracture method. Crack resistance and a parameter indirectly related to fracture toughness were measured in 48 enamel specimens from 16 permanent teeth and 12 enamel specimens obtained from six primary teeth. The Vickers microhardness number of the middle portion was greater than the upper portion in primary enamel. The fracture toughness was highest in the middle portion of permanent enamel, because fracture toughness greatly depends upon microstructure. These findings suggest that primary teeth are not miniature permanent teeth but have specific and characteristic mechanical properties.

Caldwell-Luc procedure for retrieval of displaced root in the maxillary sinus.

OBJECTIVE: The aim of this study was to describe the standard diagnostic procedure and the application of the Caldwell-Luc approach for the retrieval of a displaced root from the maxillary sinus and to share our experience in treating this complication. STUDY DESIGN: Twenty-four patients with a fractured root accidentally displaced into the maxillary sinus were referred by general dentists to our department from 2005 to 2008. All were managed by a standardized diagnostic procedure and a Caldwell-Luc approach. We recorded the age of each patient, the gender, the tooth, the size of root fragment, the type of displacement the delay between displacement and retrieval, the length of operating time, and any complications. RESULTS: Over a 4-year period, we treated 24 patients, 14 being male and 10 female. Ages ranged from 14 to 55 years (average 26.4). The commonest tooth involved was the maxillary first molar; the length of the root fragments ranged from 3 to 7 mm. Seventeen of these roots were mobile and 7 fixed (4 being located between the sinus membrane and the bone and 3 immobilized by the sinus membrane. Twenty-three of the operations were completed in 30 minutes, and only 2 patients had a temporary complication of sinusitis. No infraorbital paresthesia occurred. CONCLUSIONS: The standardized diagnostic procedure and Caldwell-Luc approach for the retrieval of a displaced root form the maxillary sinus is a safe, simple, and fast method with minimal complications.

The reduction in fatigue crack growth resistance of dentin with depth.

The fatigue crack growth resistance of dentin was characterized as a function of depth from the dentino-enamel junction. Compact tension (CT) specimens were prepared from the crowns of third molars in the deep, middle, and peripheral dentin. The microstructure was quantified in terms of the average tubule dimensions and density. Fatigue cracks were grown in-plane with the tubules and characterized in terms of the initiation and growth responses. Deep dentin exhibited the lowest resistance to the initiation of fatigue crack growth, as indicated by the stress intensity threshold (ΔK(th) ≈ 0.8 MPa•m(0.5)) and the highest incremental fatigue crack growth rate (over 1000 times that in peripheral dentin). Cracks in deep dentin underwent incremental extension under cyclic stresses that were 40% lower than those required in peripheral dentin. The average fatigue crack growth rates increased significantly with tubule density, indicating the importance of microstructure on the potential for tooth fracture. Molars with deep restorations are more likely to suffer from the cracked-tooth syndrome, because of the lower fatigue crack growth resistance of deep dentin.

Dilaceration among Nigerians: prevalence, distribution, and its relationship with trauma.

Dilaceration is the result of a developmental anomaly in which an abrupt change in the axial inclination between crown and root is observed. Its prevalence in various races is different and its association with history of trauma is controversial. This study assessed the prevalence and distribution of dilacerated teeth among Nigerians and also investigated whether there was a relation between a history of trauma and teeth that had dilaceration. A total of 465 records of adult attendees (involving 706 teeth and 256 films) were retrospectively studied. Dilacerated teeth were scored using Hamasha et al.'s criteria. Dilaceration occurred more often in the maxilla, posterior teeth and in women, though no association between a history of trauma and occurrence of dilaceration was found. Prevalence of dilaceration in the population and in all teeth was 4.5% and 2.97%, respectively. Dentists should pay detailed attention to baseline radiographs, especially in maxilla and posterior teeth.

Morphology and fracture of enamel.

This study examines the inter-relation between enamel morphology and crack resistance by sectioning extracted human molars after loading to fracture. Cracks appear to initiate from tufts, hypocalcified defects at the enamel-dentin junction, and grow longitudinally around the enamel coat to produce failure. Microindentation corner cracks placed next to the tufts in the sections deflect along the tuft interfaces and occasionally penetrate into the adjacent enamel. Although they constitute weak interfaces, the tufts are nevertheless filled with organic matter, and appear to be stabilized against easy extension by self-healing, as well as by mutual stress-shielding and decussation, accounting at least in part for the capacity of tooth enamel to survive high functional forces.

Fracture modes in human teeth.

The structural integrity of teeth under stress is vital to functional longevity. We tested the hypothesis that this integrity is limited by fracture of the enamel. Experiments were conducted on molar teeth, with a metal rod loaded onto individual cusps. Fracture during testing was tracked with a video camera. Two longitudinal modes of cracking were observed: median cracking from the contact zone, and margin cracking along side walls. Median cracks initiated from plastic damage at the contact site, at first growing slowly and then accelerating to the tooth margin. Margin cracks appeared to originate from the cemento-enamel junction, and traversed the tooth wall adjacent to the loaded cusp from the gingival to the occlusal surface. All cracks remained confined within the enamel shell up to about 550 N. At higher loads, additional crack modes--such as enamel chipping and delamination--began to manifest themselves, leading to more comprehensive failure of the tooth structure.

Dislocation of an upper third molar into the maxillary sinus after a severe trauma: a case report.

Dental injuries are common following facial trauma. This article presents a rare injury: the dislocation of a third molar into the maxillary sinus after complex mandibular and maxillary tuberosity fractures. The possible mechanism and clinical treatment are discussed.