Utilidad de la microscopía electrónica de barrido de retrodispersión en el estudio de periimplantitis.

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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

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

Vascular labeling of the head and neck vessels : technique, advantages and limitations

Vascular staining techniques have been used to describe the vascular structures of several anatomic areas. However, few reports have described this procedure in the head and neck region. This paper describes a head and neck vascular labeling procedure, and describes some of the technical complications that may occur. Fifteen specimen cadaver heads were prepared. After drying the vascular system, the internal carotid arteries were ligated and a solution with latex and a gelling agent was injected into the internal carotid arteries and external jugular veins. Two different colors were employed to differentiate arteries from veins. A total of 60ml latex was injected into each blood vessel. Subsequently, the specimens were refrigerated at 5°C for a minimum of 24 hours. Finally, a dissection was performed to identify the venous and arterial systems of the maxillofacial region. In most specimens, correct identification of the vascular structures (lingual artery, pterigoyd plexus, and the major palatal arteries, among others) was possible. However, in three heads a major technical problem occurred (the latex remained liquid), making the dissection unfeasible. Other minor complications such as latex obstruction due to the presence of atheromas were found in two further specimens. The vascular labeling technique is a predictable, effective and simple method for analyzing the vascular system of the maxillofacial area in cadaveric studies, including vessels of reduced diameter or with an intraosseous course. This procedure can be especially useful to teach vascular anatomy to dental students and postgraduate residents

Exclusion of PAX9 and MSX1 mutation in six families affected by tooth agenesis. A genetic study and literature review

Objectives: In the present study, it is described the phenotypical analysis and the mutational screening, for genes PAX9 and MSX1, of six families affected by severe forms of tooth agenesis associated with other dental anomalies and systemic entities. Study Design: Six families affected by severe tooth agenesis associated with other dental anomalies and systemic entities were included. Oral exploration, radiological examination, medical antecedents consideration and muta - tional screening for PAX9 and MSX1 were carried out. Results: No mutations were discovered despite the fact that numerous teeth were missing. An important pheno - typical variability was observed within the probands, not being possible to establish a parallelism with the pat - terns associated to previously described PAX9 and MSX1 mutations. Conclusions: These results bring us to conclude that probably other genes can determine phenotypical patterns of dental agenesis in the families studied, different than the ones described in the mutations of PAX9 and MSX1. Moreover, epigenetic factors can be involved, as those that can reduce gene dosage and other post-transcriptional modulation agents, causing dental agenesis associated or not with systemic anomalies

Betel and tobacco chewing habit and its relation to risk factors for periodontal disease

OBJECTIVES: To comparatively assess periodontal status in patients who chew different products and patients who do not have this habit and to assess how this practice interacts with predisposing factors and risk indicators of disease. METHODS: Patients included in the dental care carried out in a rural community in India were considered for a cross-sectional study. The simplified oral hygiene index and the community periodontal index (CPI) were assessed. Furthermore, a validated survey with items concerning chewing habits was administered. Statistical analysis of the effects of age range, gender, chewing products and hygiene status on CPI was performed. RESULTS: In total, 1,023 patients met the inclusion criteria. The chewer patients (430) exhibited a significantly higher CPI than the non-chewers (593). The chewing habit increased the likelihood of a higher CPI by 6.76-fold, while excellent-good oral hygiene status decreased the probability of a higher CPI by approximately 45%. CPI did not differ significantly among chewers of different products. CONCLUSION: In the population studied, a chewing habit was associated with a worse periodontal status, and this association was not modified by gender and age as predisposing factors. Oral hygiene could decrease the effect of chewing habit on periodontal health

Histomorphometric analysis of osseointegrated grade V titanium mini transitional implants inEdentulous mandible by backscattered scanning electron microscopy (BS-SEM)

The purpose of this study is to assess the use of grade V titanium mini transitional implants(MTIs) immediately loaded by a temporary overdenture. For this, a histomorphometric analysisof the bone area fraction occupancy (BAFO) was performed by backscattered scanning electronmicroscopy (BS-SEM). Four female patients were submitted to surgery in which two MTIs wereinstalled and immediately loaded with a temporary acrylic prosthesis. During the same surgery,two regular diameter implants were placed inside the bone and maintained without mechanical load.After 8 months, the MTIs were extracted using a trephine and processed for ultrastructural boneanalysis by BS-SEM, and the regular-diameter implants were loaded with an overdenture device.A total of 243 BAFOs of MTIs were analyzed, of which 94 were mainly filled with cortical bone,while 149 were mainly filled with trabecular bone. Bone tissue analysis considering the total BAFOswith calcified tissues showed 72.13% lamellar bone, 26.04% woven bone, and 1.82% chondroid bonewithout significant differences between the samples. This study revealed that grade V titanium usedin immediately loaded MTI was successfully osseointegrated by a mature and vascularized bonetissue as assessed from the BAFO

A Regenerative Endodontic Approach in Mature Ferret Teeth Using Rodent Preameloblast-conditioned Medium

Background: This study evaluated the effectiveness of a regenerative endodontic approach to regenerate the pulp tissue in mature teeth of ferret. The presence of odontoblast-like cells in the newly-formed tissue of teeth treated with or without preameloblast-conditioned medium was evaluated based on morphological criteria. Materials and methods: Twenty-four canines from six ferrets were treated. The pulp was removed, and the apical foramen was enlarged. After inducing the formation of a blood clot, a collagen sponge with or without preameloblast-conditioned medium was placed underneath the cementoenamel junction. The samples were analyzed at the eighth week of follow-up. Results: Vascularized connective tissue was observed in 50% of teeth, without differences between groups. The tissue occupied the apical third of the root canals. Odontoblast-like cells were not observed in any group. Conclusion: Revitalization of mature teeth is possible, at least in the apical third of the root canal. Further experimental research is needed to produce more reliable outcomes

Nanostructured Zn-substituted monetite based material induces higher bone regeneration than anorganic bovine bone and β-Tricalcium phosphate in vertical augmentation model in rabbit calvaria

The capacity of a nanostructured multicomponent material composed of Zn-substituted monetite, amorphous calcium phosphate, hydroxyapatite and silica gel (MSi) to promote vertical bone augmentation was compared with anorganic bovine bone (ABB) and synthetic β-tricalcium phosphate (β-TCP). The relation between biological behavior and physicochemical properties of the materials was also studied. The in vivo study was conducted in a vertical bone augmentation model in rabbit calvaria for 10 weeks. Significant differences in the biological behavior of the materials were observed. MSi showed significantly higher bone regeneration (39%) than ABB and β-TCP (24%). The filled cylinder volume was similar in MSi (92%) and ABB (91%) and significantly lower in β-TCP (81%) implants. In addition, β-TCP showed the highest amount of non-osteointegrated particles (17%). MSi was superior to the control materials because it maintains the volume of the defect almost full, with the highest bone formation, the lowest number of remaining particles, which are almost fully osteointegrated and having the lowest amount of connective tissue. Besides, the bone formed was mature, with broad trabeculae, high vascularization and osteogenic activity. MSi resorbs gradually over time with an evident increment of the porosity and simultaneous colonization for vascularized new bone. In addition, the osteoinductive behavior of MSi material was evidenced

Inervación sensitiva y crecimiento mandibular: propuesta de modelo experimental para acceso quirúrgico al nervio alveolar inferior preservando estructuras musculoesqueléticas en Conejo New Zealand White pos-destetados

Numerosos estudios reflejan vínculos entre la inervación sensitiva y el desarrollo de la estructura ósea mandibular. Con la finalidad de obtener un modelo in vivo para estudiar el efecto de la alteración de la inervación sensitiva sobre el crecimiento mandibular, se propone un acceso quirúrgico al nervio alveolar inferior que evita dañar las estructuras músculo-esqueléticas consideradas esenciales en el crecimiento craneofacial. El modelo utilizado fue el conejo New Zealand White post-destetado. Primera etapa: se realizó un estudio mediante disección anatómica para elegir una vía de acceso quirúrgico. Se eligió el acceso por la región submandibular. Desde esta zona, se accede al nervio en su punto de ingreso al canal mandibular, entre la rama mandibular y el músculo pterigoideo medial. Segunda etapa: Se utilizaron 12 especímenes a los cuales se aplicó el procedimiento quirúrgico diseñado con ayuda y supervisión veterinaria. Posteriormente, los animales fueron controlados bajo condiciones estandarizadas durante 90 días. Se evaluaron los siguientes aspectos: 1. Progreso de curación de herida quirúrgica; 2. Se utilizó un protocolo de valoración de aplicabilidad del diseño quirúrgico basado en las directrices generales de Morton y Griffitt para detección de dolor y disconfort en animales de experimentación y las directrices específicas del Southwestern Medical Center para evaluación de dolor y disconfort en conejos. Según los parámetros analizados, no se observaron valores indicadores de inaplicabilidad del protocolo propuesto. El progreso de la herida quirúrgica se consideró normal. Estudios que analizan la participación de la inervación sensitiva en aspectos fisiológicos mandibulares muestran vías quirúrgicas para modificar la estructura nerviosa que implican alteraciones musculoesqueléticas. El procedimiento aquí presentado preserva estas estructuras y es bien tolerado por este animal en etapas tempranas de crecimiento. En consecuencia resulta una alternativa viable para estudiar la participación de la inervación sensitiva en el crecimiento mandibular

Mandible measurements and dental midline deviation after alveolar nerve transection in growing rabbits

Summary: 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 problems in the masticatory system