Cytotoxicity of Reparative Endodontic Cements on Human Periodontal Ligament Stem Cells

ABSTRACT Objective To compare the cytotoxicity of commercial reparative endodontic cements on human periodontal ligament stem cells (hPDLSCs). Material and Methods The culture of hPDLSCs was established. Cell density was set at 2 × 104 cells/well in 96-well plates. Extracts of Biodentine, Bio-C Repair, Cimmo HD, MTA Repair HP and White MTA were prepared. Then, the extracts were diluted (pure, 1:4 and 1:16) and inserted into cell-seeded wells for 24, 48, and 72 h to assess cell viability through MTT assay. hPDLSCs incubated with culture medium alone served as a negative control group. Data were analyzed by Two-Way ANOVA and Tukey's test (α=0.05). Results At 24 h, pure extract of MTA Repair HP and Biodentine 1:16 presented higher cell viability compared to control. Lower cell viability was found for pure extract of Cimmo HD, MTA Repair HP 1:4 and 1:16, and White MTA 1:16. At 48 h, pure extract of Bio-C Repair and MTA Repair HP presented higher cell viability compared to control. At 72 h, only the pure extract of MTA Repair HP led to higher cell proliferation compared to control. Conclusion Biodentine, Bio-C Repair and MTA Repair HP were able to induce hPDLSCs proliferation. Cimmo HD and White MTA were found to be mostly cytotoxic in hPDLSCs.

Relaciones endoperiodontales: una frontera transitable / Endoperiodontal relationships: a passable border

La existencia de una íntima conexión entre el conducto radicular y el ligamento periodontal, ha dado lugar a lo que se conoce como relaciones endoperiodontales. Esto se debe a la presencia de varias vías anatómicas de comunicación entre ambas entidades: el foramen apical, los forámenes laterales pertenecientes a conductos accesorios y conductillos dentinarios en zonas de ausencia del cemento dentario protector. Los microorganismos y sus agentes tóxicos tienen la capacidad de afectar ambos tejidos en esa interrelación física y biológica. El diagnóstico diferencial entre enfermedad endodóntica y periodontal es de vital importancia para la elección del tratamiento y el pronóstico a distancia.

The intimate connection between the root canal and theperiodontal ligament generates a concept that is known asendo-periodontal relationships. This is due to the presence ofseveral anatomical communications between them: apical foramen,lateral foramina and dentinal tubules denuded of theircementum coverage. Microorganisms and their toxic agentscan affect both tissues due to this physical and biological interrelation.Proper differential between endodontic and periodontaletiology is vital to the accurate choice of treatment andfor the long term prognosis.

New methodology for evaluating osteoclastic activity induced by orthodontic load

Orthodontic tooth movement (OTM) is a dynamic process of bone modeling involving osteoclast-driven resorption on the compression side. Consequently, to estimate the influence of various situations on tooth movement, experimental studies need to analyze this cell. Objectives The aim of this study was to test and validate a new method for evaluating osteoclastic activity stimulated by mechanical loading based on the fractal analysis of the periodontal ligament (PDL)-bone interface. Material and Methods The mandibular right first molars of 14 rabbits were tipped mesially by a coil spring exerting a constant force of 85 cN. To evaluate the actual influence of osteoclasts on fractal dimension of bone surface, alendronate (3 mg/Kg) was injected weekly in seven of those rabbits. After 21 days, the animals were killed and their jaws were processed for histological evaluation. Osteoclast counts and fractal analysis (by the box counting method) of the PDL-bone interface were performed in histological sections of the right and left sides of the mandible. Results An increase in the number of osteoclasts and in fractal dimension after OTM only happened when alendronate was not administered. Strong correlation was found between the number of osteoclasts and fractal dimension. Conclusions Our results suggest that osteoclastic activity leads to an increase in bone surface irregularity, which can be quantified by its fractal dimension. This makes fractal analysis by the box counting method a potential tool for the assessment of osteoclastic activity on bone surfaces in microscopic examination. .

Análise histométrica do processo de reparo do reimplante dentário submetido à terapia com laser de baixa intensidade: estudo em ratos / Histommetric analyisis of tooth immediate replantation repair process submitted to low level laser therapy: study in rats

Para averiguar a influência da terapia com laser de baixa intensidade (LLLT) no processo de reparo em reimplante dentário, 90 ratos divididos em 3 grupos de 30 animais tiveram o incisivo superior direito extraído. No grupo C o incisivo foi reimplantado sem intervenção adicional. Nos grupos L1 e L2, os dentes foram irradiados com laser diodo antes, no interior do alvéolo, e logo após o reimplante, na parte externa do alvéolo. Essa dose foi repetida as 24, 48 e 72 horas pós-operatórias no grupo L1 e as 48, 96 e 144 horas no grupo L2. Após períodos de 7, 14 e 30 dias, os animais foram sacrificados para análise histológica em hematoxilina e eosina e Picrosirius Red. Observamos valores menores de inflamação no ligamento periodontal no grupo L1 (p<0,05) aos 7 dias. Maior extensão de ligamento periodontal reinserido, nos grupos L1 e L2, aos 7 e 14 dias. Maior extensão de tecido pulpar normal foi encontrada nos grupos L1 e L2 no período de 14 dias. Maior comprometimento pela reabsorção radicular foi observado no grupo C aos 30 dias. Pode-se concluir que a terapia com LLLT influiu positivamente no reparo do ligamento periodontal e tecido pulpar do dente reimplantado.

To investigate the influence of low intensity laser therapy (LLLT) in the repair process of dental reimplantation, 90 mice divided into 3 groups of 30 animals had the right upper incisor extracted. In group C the incisive was reimplanted without further intervention. In the groups L1 and L2, the teeth were irradiated with diode laser before, inside the socket, and after reimplantation, outside of the socket. This dose was repeated 24, 48 and 72 hours after surgery, the group L1 and 48, 96 and 144 hours in the L2 group. After periods of 7, 14 and 30 days, the animals were sacrificed for histological examination with hematoxylin and eosin and Picrosirius Red. We observed smaller values of inflammation in the periodontal ligament in the L1 group (p <0.05) at 7 days. Increased length of periodontal ligament reinserted in the L1 and L2 groups at 7 and 14 days. Greater extent normal pulp tissue was found in the groups L1 and L2 within 14 days. Greater commitment by root resorption was observed in group C at 30 days. It can be concluded that LLLT therapy had a positive influence on the repair of the periodontal ligament and the pulp tissue reimplanted tooth.

Reasons for mini-implants failure: choosing installation site should be valued!

Mini-implant loss is often associated with physical and mechanical aspects that result from choosing an inappropriate placement site. It is worth highlighting that: a) Interdental alveolar bone crests are flexible and deformable. For this reason, they may not offer the ideal absolute anchorage. The more cervical the structures, the more delicate they are, thus offering less physical support for mini-implant placement; b) Alveolar bone crests of triangular shape are more deformable, whereas those of rectangular shape are more flexible; c) The bases of the alveolar processes of the maxilla and the mandible are not flexible, for this reason, they are more likely to receive mini-implants; d) The more cervical a mini-implant is placed, the higher the risk of loss; the more apical a mini-implant is placed, the better its prognosis will be; e) 3D evaluations play a major role in planning the use of mini-implants. Based on the aforementioned considerations, the hypotheses about mini-implant loss are as follows: 1) Deflection of maxillary and mandibular alveolar processes when mini-implants are more cervically placed; 2) Mini-implants placed too near the periodontal ligament, with normal intra-alveolar tooth movement; 3) Low bone density, low thickness and low alveolar bone volume; 4) Low alveolar cortical bone thickness; 5) Excessive pressure inducing trabecular bone microfracture; 6) Sites of higher anatomical weakness in the mandible and the maxilla; 7) Thicker gingival tissue not considered when choosing the mini-implant.

As perdas de mini-implantes estão quase sempre relacionadas aos aspectos físicos e mecânicos decorrentes de uma escolha inadequada do local de inserção. Deve se destacar que: a) As cristas ósseas alveolares interdentárias têm flexão e se deformam, e podem não oferecer ancoragem tão absoluta. Quanto mais cervicais, as estruturas são mais delicadas e oferecem menos suporte físico para os mini-implantes; b) as cristas ósseas alveolares triangulares se deformam mais, e as retangulares são menos flexíveis; c) as bases do processo alveolar nos corpos da maxila e mandíbula não têm capacidade flexiva, e seu volume e estruturas são maiores, logo, são mais receptivas para mini-implantes; d) quanto mais próximo da cervical se coloca um mini-implante, maior é o risco de se perdê-lo; quanto mais apical se coloca o mini-implante, melhor é o seu prognóstico; e) avaliar a região tridimensionalmente representa um passo fundamental no planejamento do uso de mini-implantes. Com base nessas considerações, as hipóteses para a perda de mini-implantes são: 1) Deflexão do processo alveolar da maxila e mandíbula, quando fixados em posições mais cervicais; 2) proximidade com o ligamento periodontal e o movimento dentário intra-alveolar normal; 3) densidade óssea menor, pouca espessura e menor volume ósseo alveolar; 4) espessura menor da cortical óssea alveolar; 5) pressão excessiva, induzindo microfraturas ósseas trabeculares; 6) locais de maior fragilidade anatômica mandibular e maxilar; 7) espessura maior do tecido gengival não considerada na escolha do mini-implante.

Importance of periodontal ligament thickness

This study evaluated whether periodontal ligament (PL) thickness varied with root size and examined the possible influence of this variation on orthodontic mechanics. Measurements were taken of the maxillary left first molar in 54 male Wistar rats. Mean mesial and distal PL thicknesses were compared between the intermediate buccal and mesiobuccal roots using paired Student's t-tests with a 5% significance level. Mean values differed significantly between roots (p < 2.2 × 10-16). PL thickness in rats is directly proportional to root dimensions.

Apical stress distribution on maxillary central incisor during various orthodontic tooth movements by varying cemental and two different periodontal ligament thicknesses: A FEM study.

Context: During fixed orthodontic therapy, when the stress levels in the periodontal ligament (PDL) exceedsan optimum level, it could lead to root resorption. Aims: To determine an apical stress incident on the maxillary central incisor during tooth movement with varying cemental and periodontal ligament thickness by Finite Element Method (FEM) modeling. Settings and Design: A three dimensional finite element model of a maxillary central incisor along with enamel, dentin, cementum, PDL and alveolar bone was recreated using EZIDCOM and AUTOCAD software. ALTAIR Hyper mesh 7.0 version was used to create the Finite Element meshwork of the tooth. This virtual model was transferred to Finite Element Analysis software, ANSYS where different tooth movements were performed. Materials and Methods: Cemental thickness at the root apex was varied from 200 μm to 1000 μm in increments of 200 μm. PDL thickness was varied as 0.24 mm and 0.15 mm. Intrusive, Extrusive, Rotation and Tipping forces were delivered to determine an apical stress for each set of parameters. Results: Results indicated that an apical stress induced in the cementum and PDL, increased with an increase in cementum and PDL thickness respectively. Apical stress induced in the cementum remained the same or decreased with an increase in the PDL thickness. Apical stress induced in the PDL decreased with an increase in the cementum thickness. Conclusion: The study concluded that the clinical delivery of an orthodontic forces will cause stress in the cementum and PDL. Hence, it is necessary to limit the orthodontic force to prevent root resorption.

Analysis of the dentin-pulp complex in teeth submitted to orthodontic movement in rats

In order to microscopically analyze the pulpal effects of orthodontic movement, 49 maxillary first molars of rats were submitted to orthodontic appliance composed of a closed coil spring anchored to the maxillary incisors, placed for the achievement of mesial movement. MATERIAL AND METHODS: Ten animals were used as the control group and were not submitted to orthodontic force; the other animals were divided into groups according to the study period of tooth movement, namely 1, 2, 3, 4, 5, 6 and 7 days. The investigation of pulp and periodontal changes included hyalinization, fibrosis, reactive dentin and vascular congestion. Statistical evaluation was performed between control and experimental groups and between periods of observation using non-parametric chi-square, Kruskal-Wallis and Dunn tests. RESULTS: There was no statistically significant difference concerning pulpal changes between control and experimental groups nor between periods of observation. The control group, at 3 and 5 days, revealed greater hyalinization of the periodontal ligament (p<0.05), whereas root resorption was significantly greater at 5 and 7 days (p<0.05). CONCLUSION: No morphological change from the effect of induced tooth movement could be found in the dentin-pulp complex. In addition, no inflammatory or pulp degeneration, detectable in optical microscopy, was found in experimental groups.

[Comparison of one versus two appointments endodontic therapy on healing of periapical lesions in dogs, teeth]

Apical periodontitis is caused by bacteria within root canals. Logically, the treatment of apical periodontitis should be directed to the removal of the cause, i.e bacterial eradication. The best procedure for disinfection is canal debridement and irrigation during the first appointment, followed by the application of calcium hydroxide dressing for one week. MTAD, a Mixture of Tetracycline isomer, Acid and Detergent is a new antibacterial solution which has been claimed to be useful in one visit treatment. The purpose of this study was to compare healing of periapical lesions after one visit treatment using MTAD with two appointments endodontic therapy by calcium hydroxide in dogs teeth. Forty incisor and first premolars of four dogs were left open for four months until periapical lesions developed. Twenty root canals were treated endodontically using MTAD in one visit, and the other 20 canals were dressed with calcium hydroxide for 1 week, and endodontic treatments were then completed. Six months after treatment the dogs were killed by vital perfusion. After fixation, the teeth were histologically examined for the healing of periapical lesions. Kruskal-wallis and Mann-Whitney tests were used for statistical analysis. The percentage of healing, advanced organization, organization, and acute inflammation for MTAD group were 3 1.6%, 26.3%, 36.8%, and 5.3%, while for calcium hydroxide group they were 16.7%, 16.7, 55.6%, and 11.1% respectively. The difference between the two groups was not statistically significant [p>0.05], but healing of lesions progressed better in MTAD group. One-visit treatment by use of MTAD for pulpless teeth with periapical lesion is an acceptable alternative therapy to two-visit treatment using calcium hydroxide

Remoción del ligamento periodontal por medio de fricción con gasa embebida en solución de hipoclorito de sodio al 1 por ciento / Periodontal ligament removal by frictioning with a gauze embedded in 1 per cent sodium hypochlorite solution

Estudios han demostrado la capacidad del hipoclorito de sodio en la remoción del ligamento periodontal sin vitalidad en dientes avulsionados. Sin embargo el uso de esta sustancia puede ocasionar un efecto irritante en el tejido conjuntivo. Siendo así adecuaciones en su utilización se muestran necesarias para que se obtenga un reparo más satisfactorio cuando utilizados en dientes reimplantados. Por lo tanto es propuesta de ese estudio evaluar la capacidad de remoción del ligamento periodontal, por medio de fricción de la superficie radicular de dientes de ratones, con una gasa humedecida en solución de hipoclorito de sodio al 1 por ciento. Fueron utilizados 40 dientes divididos en 4 grupos de 10, los cuales después de la extracción, fueron mantenidos en medio seco por 60 minutos. En el grupo control, los dientes fueron mantenidos en 25ml de hipoclorito de sodio a 1 por ciento por 5 minutos. En el grupo II, la superficie radicular fue friccionada con gasa humedecida en 25ml de solución de hipoclorito de sodio a 1 por ciento por un periodo de 1 minuto y en la secuencia lavados en suero fisiológico por 4 minutos. En el grupo III, la fricción fue de 2 minutos, y el periodo del lavado 2 minuto. En el grupo IV, la fricción con 4 minutos y el periodo del lavado 1 minuto. Después del procesamiento laboratorial, los cortes obtenidos fueron coloreados por el Tricromio de Masson y Hematoxilina y eosina para análisis en microscopia de luz. Los resultados demostraron que en el grupo control 100% de la superficie radicular estaba cubierto por ligamento periodontal. A través del test de proporción, se observó que la fricción por 1 minuto fue menos eficaz, con diferencia estadísticamente significante (p<0,0001). La remoción por completo del ligamento periodontal se obtuvo solamente en los periodos de 2 y 4 minutos.

Studies have demonstrated the capacity of the sodium hypochloride in removing the non-vital periodontal ligament in avulsed tooth. Adequacies in its use are necessary to get a repair more satisfactory when teeth are replanted. Therefore, the purpose of this study was to evaluated the capacity of removal the periodontal ligament in root surface of rats, using friction of sodium hypochloride 1% solution absorbed gauze. Forty teeth were divided in 4 groups with 10 teeth, which after the extration, had been kept in dry way per 60 minutes. In control group, the teeth had been kept in 25ml of sodium hypochloride 1% for 5 minutes. In group II, the root surface was rubbed with in 25ml of sodium hypochloride 1% solution absorbed gauze for 1 minute and rinsed for 4 minutes in saline. In group III, the friction was of 2 minutes, and the rinsed period was of 3 minutes. In the group IV, the friction was of 4 minutes and the rinsed period was of 1 minute. After laboratorial processing, the specimens had been colored by the Masson tricromic and Hematoxilin and eosin for microcopy evaluation. The results had demonstrated that in the control group 100% of the root surface was covered by periodontal ligament. By means of the ratio test, it was observed that the friction per 1 minute was less efficient, being statistically significant (p<0,0001). The complete removal of the periodontal ligament it was only gotten in the period of 2 and 4 minutes.

Sabe-se que o hipoclorito de sódio pode remover o ligamento periodontal desvitalizado em dentes avulsionados. Adequações em seu uso se mostram necessárias para se obter um reparo mais satisfatório em dentes reimplantados. Portanto, estudou-se neste trabalho a capacidade de remoção do ligamento periodontal, por meio de fricção da superfície radicular de dentes de rato, com uma gaze embebida em solução de hipoclorito de sódio a 1%. Foram utilizados 40 dentes divididos em 4 grupos de 10, os quais após a extração, foram mantidos em meio seco por 60 minutos. No grupo controle, os dentes foram mantidos em 25ml de hipoclorito de sódio a 1% por 5 minutos. No grupo II, a superfície radicular foi friccionada com gaze embebida em 25ml de solução de hipoclorito de sódio a 1% por um período de 1 minuto e na seqüência lavados em soro fisiológico por 4 minutos. No grupo III, a fricção foi de 2 minutos, e o período de lavagem foi de 3 minutos. No grupo IV, a fricção foi de 4 minutos e o período de lavagem foi de 1 minuto. Após o processamento laboratorial, os cortes foram corados pelo Tricrômico de Masson e pela hematoxilina e eosina para análise histomorfométrica. Os resultados demonstraram que no grupo controle, 100% da superfície radicular estava coberta por ligamento periodontal. Mediante o teste de proporção, observou-se que a fricção por 1 minuto foi menos eficaz, sendo estatisticamente significante (p<0,0001). A remoção completa do ligamento periodontal foi obtida somente nos período de 2 e 4 minutos.

Sobredentaduras parciales removibles / Removable partial overdentures

Una sobredentadura parcial removible es aquella prótesis que usa dientes naturales y raíces retenidas para soporte y retención, siendo similar a una dentadura parcial removible convencional con la única excepción de que las bases protéticas cubren una o más raíces retenidas. El mantener a los dientes como parte del reborde residual, contribuye a disminuir la velocidad de reabsorción de éste, a la vez que se mantienen los impulsos propioceptivos, lo que permite conservar la discriminación direccional, la sensibilidad táctil a la carga y la diferenciación del grosor y consistencia de los alimentos, casi de la misma forma que en aquellos pacientes con dientes naturales, por lo que éstos se habitúan más fácilmente a estas prótesis. Al conservar el hueso alveolar también se produce menos trauma a los tejidos remanentes, aumentándose el soporte, la retención y la estabilidad protética. Las S.P.R. también constituyen soluciones rápidas y conservadoras para los múltiples problemas que presentan los pacientes con defectos congénitos y adquiridos y son además, usadas en muchos casos como prótesis transitorias. Sin embargo, la caries y la enfermedad periodontal son los principales problemas que se presentan con el uso de este tipo de prótesis. La conservación de los soportes, así como de los dientes naturales remanentes, depende en gran parte de la motivación y destreza del paciente para mantener un alto grado de higiene bucal

Ambiente bucal: equilibrio vs. desequilibrio / Oral environment: balance vs. inbalance

Esta revisión se propone analizar el ambiente bucal considerando a los principales responsables de la homeostasis y del desbalance. Su abordaje prevé la investigación de los principales factores involucrados en el equilibrio-desequilibrio de los componentes del modelo epidemiológico: huésped, agente patógeno y sustrato. En condiciones de equilibrio se estudian ciertos aspectos del huésped: saliva, elementos dentarios, mucosa bucal y periodonto. Como resultado del interjuego de los protagonistas del modelo, se producen perturbaciones del ambiente cuya persistencia favorece la aparición de enfermedades bucodentales. El agente patógeno y el sustrato se analizan a partir del desequilibrio del medio; en el primero se considera la microflora que habita en condiciones normales y su transición a patógena, los factores que contribuyen en la adherencia y para el sustrato, la importancia de la dieta, consumo de azúcares, sustitutos, grasas, etc., en la dieta. Por último, se destacan las estrategias a seguir para revertir o impedir el desequilibrio, planteando el tratamiento de la caries dental y de la enfermedad periodontal desde el enfoque tradicional de la odontología y de los nuevos aportes, asociados algunos con la biología molecular (biomarcadores del FCG, aumento de la resistencia bacteriana, modelo del recrecimiento de la placa y de la glucólisis, etc.)

Presença do canal cavo-inter-radicular em molares superiores e inferiores / Presence of foramina in the furcation and pulp chambers of upper and lower molars

Este trabalho teve como objetivo detectar a presença do canal-inter-radicular, nas regiöes de soalho e furca de molares superiores e inferiores, através de três métodos: olho nu, lupa comum e microscópio eletrônico de varredura. Foram utilizados quinze molares superiores e quinze molares inferiores. Os resultados mostraram a presença do canal cavo-inter-radicular em 46,6 por cento dos molares inferiores e em 26,6 por cento dos molares superiores. O número de foraminas na furca foi superior ao encontrado no soalho das amostras, sendo estatisticamente significante (Z=3,22). A maior foramina detectada encontrava-se na furca de um molar inferior e a menor foramina foi encontrada no soalho de um molar inferior

Modificaciones morfofuncionales del ligamento periodontal post cirugía ortognática / Functional modifications in the periodontal ligament after orthognathic surgery

Se estudian los cambios observados en el ligamento periodontal de 49 piezas dentarias que se encontraban sin oclusión en 5 pacientes portadores de dismorfosis dentofacial. Se les efectúa un análisis clínico, cefalométrico y de radiografías retroalveolares tomadas con técnica estandarizada, para repetirlas en las mismas condiciones en el postoperatorio. Se corrige la dismorfosis y se llevan las piezas a oclusión mediante osteotomías. Se comparan el ancho del ligamento periodontal en sus tercios cervical, medio y apical, así como la movilidad dentaria. Se concluye que los cambios observados representan una respuesta adaptativa del ligamento periodontal a las nuevas condiciones funcionales recuperando éste su aspecto y fisiología normales

Cambios histológicos en el ligamento periodontal y zonas de mineralización del cemento en áreas de presión producidas por fuerzas ortodónticas en humanos / Histological changes in the periodontal ligament and cementum mineralization zones in areas of pressure produced by orthodontic forces in human beings

El movimiento ortodóncico a nivel dental, causa zonas de presión y zonas de tensión a ambos lados del diente. Se ha descrito cómo en las zonas de presión se observa una región mineralizada relacionada con el cemento radicular y el ligamento periodontal, pero no se sabe con certeza su origen ni sus posibles efectos secundarios. El propósito de este estudio es confirmar la presencia de este tejido mineralizado, determinar si es constante y analizar los eventos celulares para determinar su relación con la anquilosis por trauma y posible subsecuente reabsorción radicular. El experimento se diseñó de tal forma que se obtuvieron treinta y dos especímenes de primeros premolares superiores humanos. Las muestras fueron procesadas para realizar cortes histológicos (microscopía de luz); y para microscopía electrónica de Scanner (SEM y X-ray microanalysis). Los hallazgos indican que a nivel de las zonas de presión producidas por fuerzas ortodónticas, en humanos, se presenta un tejido mineralizado, de tipo cementoide, que produce una unión íntima y focal con el hueso alveolar, dando como resultado una anquilosis también de tipo focal