Micro-computed tomographic analysis of apical foramen enlargement of mature teeth: a cadaveric study / Análisis mediante micro-CT del ensanchamiento del foramen apical de dientes maduros: un estudio cadavérico

Revitalization procedures have been extensively studied during the last decade and offers several advantages over root canal treatment, such as the recovery of the natural immune system. Mature teeth have a small apical foramen diameter (AFD), which could impair the ingrowth of tissue into the root canal. We analysed three methods for apical foramen enlargement by instrumentation in in situ human teeth and evaluated the damage over hard tissues produced by the techniques. Tooth length (TL), defined as the length from the most coronal part of the crown to the point at which the file abandons the root canal, was calculated. Forty-four in situ teeth were randomized: Group I: instrumentation 0.5 mm coronal to TL; Group II: at TL level; Group III: 0.5 mm beyond TL. Teeth were instrumented up to K-file #80. The mandibles were scanned in a micro-CT device before and after treatment. Group I: Only 20 % of teeth presented an enlarged AFD, with augmentation of 0.09 mm. No damage to hard tissues was observed. Group II: 71.4 % of the teeth presented an enlarged AFD with augmentation of 0.42 mm. 35.7 % presented damage to periapical tissues. Group III: 86.7 % presented an enlarged AFD with augmentation of 0.43 mm. 46.7 % presented damage to periapical tissues. All groups presented similar prevalence of teeth with dentine thickness less than 1mm. All mandibular incisors presented areas of thickness less than 1mm. Instrumentation 0.5 mm beyond TL is the most effective technique.

La revitalización de dientes necróticos ha sido ampliamente estudiada durante la última década y ofrece varias ventajas sobre la endodoncia convencional, tal como la recuperación del sistema inmunitario natural del diente. Los dientes maduros tienen un diámetro de foramen apical (FA) pequeño, lo que podría afectar el crecimiento de tejido en el conducto. Se evaluaron tres métodos para la ampliación del foramen apical en dientes humanos in situ y se evaluó el daño sobre los tejidos duros producidos por las técnicas. Mediante radiografía periapical se calculó la longitud del diente (TL), definida como la longitud desde la parte más coronal de la corona hasta el punto en que la lima abandonó el conducto radicular. En el estudio fueron aleatorizados 44 dientes in situ: Grupo I: instrumentación 0,5 mm coronal a TL; Grupo II: a nivel TL; Grupo III: 0,5 mm más allá de TL. Los dientes fueron instrumentados hasta la lima K #80. Las mandíbulas se escanearon en un dispositivo de microCT antes y después del tratamiento. Grupo I: solo el 20 % de los dientes presentaron un diámetro de FA ensanchado, con un aumento de 0,09 mm. No se observó daño a los tejidos duros. Grupo II: el 71,4 % de los dientes presentaban un FA ensanchado con un aumento de 0,42 mm. El 35,7 % presentó daño a los tejidos periapicales. Grupo III: el 86,7 % presentó un FA ensanchado con un aumento de 0,43 mm. El 46,7 % presentó daño a los tejidos periapicales. Todos los grupos presentaron una prevalencia similar de dientes con un espesor de dentina inferior a 1mm. Todos los incisivos mandibulares presentaban áreas de grosor inferior a 1mm. La instrumentación 0,5 mm más allá de TL es la técnica más efectiva, aunque se debe tener especial consideración en aspectos como el debilitamiento de la estructura dentaria.

Immediate small-diameter implants as abutments for an overdenture in the edentulous atrophic mandible: report of immersion endoscopic bone in vivo, and histologic bone-implant evaluation after 6 months of function / Implantes de pequeño diámetro como soporte inmediato de sobredentaduras en hueso alveolar mandibular atrófico: reporte de endoscopía de inmersion in vivo y evaluación histológica a los 6 meses de función

The aim of this report was to endoscopically evaluate bone quality in vivo in the immediate installation of temporary small-diameter implants, and again after 6 months of function, through an attachments system for overdenture, in the atrophic mandible of a patient. We also histologically evaluated bone-implant interaction in these temporary small-diameter implants, once the success of the osseointegration of the submerged implants was guaranteed. A patient received a total of 6 implants in the atrophic mandible, two of which were immediately loaded with a provisional prosthesis, and four were left to heal in a submerged way. Further, an immersion endoscopic evaluation was performed during bone drilling, and this showed a compact bone structure with limited vascularization and predominantly cortical structure.This immediate loading protocol involving an overdenture retained by two small-diameter implants of 2.9 mm in the atrophic mandible proved to be successful after 6 months of loading. Clinical and histologic osseointegration was consistently achieved for both of the retrieved immediately loaded implants. This modality allows the patient to be restored with a stable, functional, and aesthetic prosthesis during the osseointegration period of submerged implants and soft-tissue healing, before the removal of the provisional implants. The histological evaluation of bone-implant contact found that the space between the implant threads closer to the surface was filled with woven bone and lamellar bone, but the tissue in contact with the cervical portion of the implants was compatible with cortical bone organization. Also, the newly formed bone has a regular cell distribution and characteristics of advanced maturation after 6 months of function in the atrophic mandible. Anchored overdentures in 2 to 4 small-diameter implants (2.9 mm) for edentulous patients with severe atrophy of the mandible with cortical bone would be a minimally invasive alternative.

Mandible measurements and dental midline deviation after alveolar nerve transection in growing rabbits / Medidas mandibulares y desviación de la línea mediana dental luego de la transección del nervio alveolar inferior en conejos en crecimiento

The relationship between sensitive innervation and normal mandibular bone development has been described in the literature. Therefore, neural damage is a potential cause of osseous deformities, particularly in growing subjects. The aim of this project is to present the mandible measurements obtained after the transection of the inferior alveolar nerve of growing rabbits. A specific surgical protocol was designed to carry out the unilateral nerve transection by avoiding musculoskeletal injuries. Twenty New Zealand White rabbits one week post-weaning were used, 12 as an experimental group and 8 as a control group (Sham operated). The animals were sacrificed 90 days postoperatory, and the mandibles carefully dissected. Dental midline deviation data were obtained under anesthesia, previous to sacrifice. All measurements were obtained with a micron digital caliper. For this study, only anterior-posterior measurements were obtained from five points specifically determined on the rabbit mandible. Each measurement was made three times by the same examiner and the average value was considered. Regarding the anterior-posterior measurements, the molar and incisive regions of the denervated hemimandible were significantly shorter than the corresponding regions in the non-denervated side. The control group did not show these differences. A dental midline deviation was observed, but not always directed on the operated side. However, the deviation values were greater when oriented to the denervated side. These changes did not cause evident deformity or dysfunction in the masticatory system of the animals. They were fed normally and their weight was considered within normal parameters while growing. Despite the biological relationship between sensory inervation and bone morphology, the effect of sensory denervation in early stages of bone growth appears to generate only small alterations on the mandible morphology. However, these alterations do not lead to functional proble...

Se ha descrito una importante relación entre la inervación sensitiva y aspectos biológicos mandibulares. Consecuentemente, el daño a la estructura nerviosa es una causa potencial de alteraciones en el desarrollo mandibular, sobre todo en etapas de crecimiento. El objetivo de este trabajo es presentar mediciones mandibulares realizadas posterior a una lesión del nervio sensitivo en una etapa temprana de crecimiento. Se diseñó un protocolo quirúrgico para realizar la transección del nervio alveolar inferior sin lesionar estructuras musculoesqueléticas. Veinte conejos Neo zelandeses blancos fueron utilizados, una semana post-destete, 12 como grupo experimental y 8 como grupo control. Los animales fueron sacrificados 90 días después y las mandíbulas cuidadosamente disecadas. La información de la desviación de la línea media se obtuvo bajo anestesia, previo al sacrificio. Todas las mediciones se obtuvieron con un calibrador digital. Las medidas antero-posteriores se obtuvieron a partir de cinco puntos específicamente determinados en la mandíbula del conejo. En cuanto a las medidas antero-posteriores, las región molar e incisiva de las hemimandíbulas denervadas fueron significativamente menores que la correspondiente del lado no denervado. El grupo control no mostró esta diferencia. La línea media dental siempre se observó desviada, pero no siempre hacia el lado intervenido. Sin embargo, la media de desviación fue mayor cuando ésta se orientó hacia el lado denervado. Estos cambios no causaron deformidad evidente o disfunción en el sistema masticatorio de los animales, los cuales se alimentaron normalmente. El peso de los mismos fue considerado dentro de los parámetros normales. A pesar de la relación biológica entre la inervación sensitiva y la morfología del hueso, el efecto de la denervación sensitiva en las primeras etapas de crecimiento parece generar sólo pequeñas alteraciones en la morfología mandibular. Sin embargo, éstas no conducen a problemas funcionales...