Evaluación de la mineralización en mandíbula y diente de trucha arcoíris (Oncorhynchus mykiss) mediante microscopía electrónica de barrido de presión variable acoplada a detector de espectroscopía de rayos X de energía dispersiva / Evaluation of mineralization in jaw and teeth of rainbow trout (Oncorhynchus mykiss) using variable pressure scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy detector

RESUMEN: En salmonicultura se utilizan imágenes de rayos X, para evaluar la columna vertebral y las aletas, pero estas no permiten cuantificar los minerales que constituyen el hueso, para esto se utilizan otras técnicas que son destructivas. La Microscopía Electrónica de Barrido de presión variable (VP SEM) acoplada al detector espectroscopia de rayos X de energía dispersiva (EDX) acoplado, nos permite analizar la microestructura y a la vez determinar elementos químicos, porcentaje y distribución presentes en puntos específicos en una muestra. Se utilizaron 5 truchas control y 5 con deformidad mandibular, de agua dulce en etapa de smolt, se analizó la estructura y mineralización del hueso, se eligieron en promedio 6 puntos de cuantificación por región de interés y se analizaron mediante Microscopía Electrónica de Barrido (VP SEM-EDX). Los datos obtenidos muestran porcentaje en masa de Ca promedio en hueso articular de truchas fueron de 8.07 % y de 14.48 % en truchas con deformidad mandibular y control respectivamente y el porcentaje en masa promedio de P es de 4.07 % y 7.60 %, en truchas con deformidad mandibular y control respectivamente. Se identificó además otros elementos presentes en la muestra como Mg, Na, C, O, N, S, F, Zn, Al y Fe, con especial interés en el aumento de carbono en las muestras analizadas con deformidad mandibular y la presencia de aluminio en todas las muestras. La Técnica de VP SEM-EDX, permite evaluar de forma directa, sin destrucción de la muestra y con una preparación mínima de la muestra. En el hueso, la aplicación más frecuente de SEM-EDX es la medición del contenido de Ca y P y la relación que existe entre estos elementos Ca/P, en la muestra. Paralelamente la técnica nos permite la detección de otros microelementos provenientes del agua o de la alimentación y que eventualmente pueden provocar alteraciones en los peces, confirmando la hipótesis que el microanálisis elemental tiene utilidad para la salmonicultura.

SUMMARY: In salmon farming systems, X-ray images are used to evaluate the spine and fins, but these do not allow quantifying the minerals that make up the bone, for different techniques that are destructive are used. Variable Pressure Scanning Electron Microscopy (VP SEM) coupled to an Energy Dispersive X-ray spectroscopy detector (EDX), allows us to analyze the microstructure and at the same time determine chemical elements, percentages, and distribution present at specific points in a sample. Five control and five jaw deformity trout, from freshwater and in the smolt stage were used. The structure and mineralization of the bone were analyzed, an average six quantification points were chosen per region of interest (ROI) and then they were analyzed by Scanning Electron Microscopy (VP SEM-EDX). The data obtained have shown the average mass percentage of calcium in trout joint bone was 8.07 % and 14.48 % in jaw deformity and control trout, respectively; and the average mass percentage of phosphorus is 4.07 % and 7.60 %, in jaw deformity and control trout, respectively. Other elements present in the sample were also identified, such as magnesium, sodium, carbon, oxygen, nitrogen, sulphur, fluorine, zinc, aluminium, and iron, with special interest the increase of carbon in the analyzed samples with mandibular deformity and the presence of aluminum in all samples. The VP SEM-EDX Technique allows direct evaluation, without destruction of the sample and with minimal sample preparation. In bone, the most frequent application of SEM-EDX is the measurement of the content of calcium (Ca) and phosphorus (P) and the relationship that exists between these elements, calcium/phosphorus (Ca/P), in the sample. At the same time, the technique allows us to detect other microelements from water or food that can eventually cause alterations in fish, confirming the hypothesis that elemental microanalysis is useful for salmon farming.

Development of a Rat Model of Mandibular Irradiation Sequelae for Preclinical Studies of Bone Repair.

Repairing mandibular bone defects after radiotherapy of the upper aerodigestive tract is clinically challenging. Although bone tissue engineering has recently generated a number of innovative treatment approaches for osteoradionecrosis (ORN), these modalities must be evaluated preclinically in a relevant, reproducible, animal model. The objective of this study was to evaluate a novel rat model of mandibular irradiation sequelae, with a focus on the adverse effects of radiotherapy on bone structure, intraosseous vascularization, and bone regeneration. Rats were irradiated with a single 80 Gy dose to the jaws. Three weeks after irradiation, mandibular bone defects of different sizes (0, 1, 3, or 5 mm) were produced in each hemimandible. Five weeks after the surgical procedure, the animals were euthanized. Explanted mandibular samples were qualitatively and quantitatively assessed for bone formation, bone structure, and intraosseous vascular volume by using micro-computed tomography, scanning electron microscopy, and histology. Twenty irradiated hemimandibles and 20 nonirradiated hemimandibles were included in the study. The bone and vessel volumes were significantly lower in the irradiated group. The extent of bone remodeling was inversely related to the defect size. In the irradiated group, scanning electron microscopy revealed a large number of polycyclic gaps consistent with periosteocytic lysis (described as being pathognomonic for ORN). This feature was correlated with elevated osteoclastic activity in a histological assessment. In the irradiated areas, the critical-sized defect was 3 mm. Hence, our rat model of mandibular irradiation sequelae showed hypovascularization and osteopenia. Impact statement Repairing mandibular bone defects after radiotherapy of the upper aerodigestive tract is clinically challenging. Novel tissue engineering approaches for healing irradiated bone must first be assessed in animal models. The current rat model of mandibular irradiation sequelae is based on tooth extraction after radiotherapy. However, the mucosal sequelae of radiotherapy often prevent the retention of tissue-engineered biomaterials within the bone defect. We used a submandibular approach to create a new rat model of mandibular irradiation sequelae, which enables the stable retention of biomaterials within the bone defect and should thus facilitate the assessment of bone regeneration.

Molecular alterations of newly formed mandibular bone caused by zoledronate.

Bone quality is defined by structural and material characteristics. Most studies on the mandible have focused on the analysis of structural characteristics, with insufficient investigation of material characteristics. This study tested whether zoledronate affects the material characteristics of newly formed mandibular bone. Thirty-six female Wistar rats were assigned to three groups: sham-ovariectomized rats (SHAM, n=12), ovariectomized rats (OVX, n=12), and ovariectomized rats treated with zoledronate (ZOL, n=12). The left side of the mandibular ramus of all rats was drilled bicortically. Twenty-eight days after surgery, all surviving rats were euthanized and all mandibles were removed. Raman microspectroscopy was performed, and five spectra per specimen of newly formed mandibular bone were analysed. Compared with OVX rats, the mineral/matrix ratio in ZOL rats was significantly increased (5.43±1.88 vs. 7.86±2.05), while crystallinity (0.055±0.002 vs. 0.050±0.002), relative proteoglycan content (0.43±0.10 vs. 0.31±0.05), and collagen structural integrity (1.16±0.21 vs. 0.72±0.06) were significantly decreased. These changes in material characteristics may explain why rats that received zoledronate exhibited peculiar biological phenomena such as bisphosphonate-related osteonecrosis of the jaw.

Effects on Bone Tissue After Osteotomy with Different High-Energy Lasers: An Ex Vivo Study.

OBJECTIVE: The purpose of this study was to evaluate the application of Er:YAG and Er,Cr:YSGG lasers during osteotomy in bovine bone blocks. BACKGROUND DATA: Er:YAG/Er,Cr:YSGG lasers for osteotomy procedures have been used to induce tissue ablation without thermal damage. However, even these lasers can induce thermal damages, which can cause a delay on the bone healing. MATERIALS AND METHODS: Sixty standardized bovine bone mandible samples were divided into three groups with 20 samples each: Group 1, Bur; Group 2, Er:YAG laser; and Group 3, Er,Cr:YSGG laser. Two irradiations/cuts were made in each sample. The first was performed until the sample was completely separated into two fragments, and the time required for this procedure was recorded in seconds. The second irradiation/cut was made the same way as the first one; however, it was made partially, without separating the sample into two fragments, but rather making sulci ∼1.5-2 mm deep. Ten samples in each group were used to evaluate the surface morphology of the osteotomy by scanning electron microscopy (SEM), while the other 10 samples were submitted to descriptive histological analysis. RESULTS: The bur was the instrument that performed the osteotomy in the shortest amount of time (p < 0.05). All the instruments caused thermal damage; however, the Er,Cr:YSGG laser was the only type that induced carbonization. CONCLUSIONS: The Er:YAG laser induced the lowest degree of thermal damage in bone tissue after osteotomy; however, a shorter clinical time was required to perform the osteotomy in the bur group.

Development of a biointegrated mandibular reconstruction device consisting of bone compatible titanium fiber mesh scaffold.

Coating biomaterials with a thin hydroxyapatite (HA) was proven effective in enhancing bone compatibility. Segmental bone defects are considered as the most difficult defect to repair in bone regeneration therapy. We developed submicron-thin HA-coated titanium fiber mesh scaffolds to reconstruct immediately loaded segmental mandibular defects and evaluated their bone compatibility in vitro and in vivo. Human osteoblasts attachment, proliferation, and osteocalcin expression in non- and HA-coated scaffolds were evaluated. A 10-mm long segmental bone defect in a rabbit mandibular bone was reconstructed with non- or HA-coated scaffolds, which were removed at 9 and 21 weeks, to evaluate the mechanical strength of the bone-scaffold connection and the bone formation around the scaffold. Expression of osteocalcin was greater in HA-coated scaffolds. In vivo bone formation in HA-coated scaffolds was greater than that in non-coated scaffolds at 21 weeks. Newly formed bone in HA-coated scaffolds mostly restored bone continuity. Scanning electron microscopy identified strong integration of the bone and HA-coated scaffolds. The mechanical strength of the bone-scaffold connection was 3-fold greater in HA-coated scaffolds than that in non-coated scaffolds. These results suggest that a thin HA-coated titanium fiber mesh scaffold is a bone-compatible mandibular reconstruction device in immediately loaded segmental defects.

A comparative investigation of bone surface after cutting with mechanical tools and Er:YAG laser.

BACKGROUND AND OBJECTIVES: Despite of the long history of medical application, laser ablation of bone tissue became successful only recently. Laser bone cutting is proven to have higher accuracy and to increase bone healing compared to conventional mechanical bone cutting. But the reason of subsequent better healing is not biologically explained yet. In this study we present our experience with an integrated miniaturized laser system mounted on a surgical lightweight robotic arm. STUDY DESIGN/MATERIALS AND METHODS: An Erbium-doped Yttrium Aluminium Garnet (Er:YAG) laser and a piezoelectric (PZE) osteotome were used for comparison. In six grown up female Göttingen minipigs, comparative surgical interventions were done on the edentulous mandibular ridge. Our laser system was used to create different shapes of bone defects on the left side of the mandible. On the contralateral side, similar bone defects were created by PZE osteotome. Small bone samples were harvested to compare the immediate post-operative cut surface. RESULTS: The analysis of the cut surface of the laser osteotomy and conventional mechanical osteotomy revealed an essential difference. The scanning electron microscopy (SEM) analysis showed biologically open cut surfaces from the laser osteotomy. The samples from PZE osteotomy showed a flattened tissue structure over the cut surface, resembling the "smear layer" from tooth preparation. CONCLUSIONS: We concluded that our new finding with the mechanical osteotomy suggests a biological explanation to the expected difference in subsequent bone healing. Our hypothesis is that the difference of surface characteristic yields to different bleeding pattern and subsequently results in different bone healing. The analyses of bone healing will support our hypothesis.

Nonvascular transport distraction osteogenesis in bone formation and regeneration. Is it an accidental phenomenon?

PURPOSE: To explore the osteogenic mechanism of nonvascular transport distraction osteogenesis (NTDO) by constructing mandibular defects in dogs. METHODS: Sixty adult dogs were randomly divided into three groups with 20 dogs in each group. Canine mandibular defect models of NTDO were constructed. Animals were euthanized 1, 4 and 12 weeks after distraction, and the transport disc and surrounding tissue were collected and fixed. Histochemical staining using hematoxylin and eosin (H&E) and electron microscopic observations were used to examine bone regeneration. RESULTS: Distraction bone regeneration was observed in the distraction gap and around the transport disc, and osseous connections had formed between new bone and the transport disc after one week. Osteoclasts gathered around the transport disc, and bone absorption pit formation could be seen. After 4 weeks of distraction, the new bone around the transport disc was close to maturity with thick sclerostin on the middle of the transport disc. After 12 weeks the new bone and the transport disc were fully integrated, and were difficult to distinguish by H&E staining and electron microscopy. CONCLUSIONS: Canine mandibular defects were successfully repaired by NTDO resulting in ideal new bone formation and fully recovered mandibular physiological function. The surrounding tissues, including musculoskeletal tissues, the periosteum and other soft tissues and the nonvascular transport disc, together contribute to bone regeneration and neovascularization in NTDO.

Chronological changes in the microstructure of bone during peri-implant healing: a microcomputed tomographic evaluation.

Our objectives were to examine the titanium-bone interfaces chronologically and to clarify the process of osseointegration using microcomputed tomography (microCT). The mandibular premolars of 3 dogs were extracted and 12 weeks later 2 Straumann dental implants were installed in each quadrant. The microstructural changes at the bone-implant interface at the first, fourth, and eighth weeks after installation were evaluated by microCT and a 3-dimensional image was constructed. The microstructural measurements at the bone-implant interface, including the trabecular number (Tb.N), bone volume fraction (BV/TV), structure model index (SMI), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp) and connectivity density (Conn.D), were measured. Experimental outcomes were analysed for correlations between time and microstructural variables of trabecular bone. Tb.N increased significantly during the eighth week compared with that during the first and fourth week (p=0.001, 0.002). BV/TV increased generally with time and there were significant differences (p=0.003) between each time group. While Tb.Sp decreased with time and changed significantly during the eighth week compared with that during the first week (p=0.021), differences in SMI, Tb.Th and Conn.D did not differ significantly according to time of implant. The significant increase in the Tb.N and BV/TV during the eighth week after insertion of implants indicates that the formation of new bone before the eighth week is the key to osseointegration.

EMMPRIN/CD147 deficiency disturbs ameloblast-odontoblast cross-talk and delays enamel mineralization.

Tooth development is regulated by a series of reciprocal inductive signaling between the dental epithelium and mesenchyme, which culminates with the formation of dentin and enamel. EMMPRIN/CD147 is an Extracellular Matrix MetalloPRoteinase (MMP) INducer that mediates epithelial-mesenchymal interactions in cancer and other pathological processes and is expressed in developing teeth. Here we used EMMPRIN knockout (KO) mice to determine the functional role of EMMPRIN on dental tissue formation. We report a delay in enamel deposition and formation that is clearly distinguishable in the growing incisor and associated with a significant reduction of MMP-3 and MMP-20 expression in tooth germs of KO mice. Insufficient basement membrane degradation is evidenced by a persistent laminin immunostaining, resulting in a delay of both odontoblast and ameloblast differentiation. Consequently, enamel volume and thickness are decreased in adult mutant teeth but enamel maturation and tooth morphology are normal, as shown by micro-computed tomographic (micro-CT), nanoindentation, and scanning electron microscope analyses. In addition, the dentino-enamel junction appears as a rough calcified layer of approximately 10±5µm thick (mean±SD) in both molars and growing incisors of KO adult mice. These results indicate that EMMPRIN is involved in the epithelial-mesenchymal cross-talk during tooth development by regulating the expression of MMPs. The mild tooth phenotype observed in EMMPRIN KO mice suggests that the direct effect of EMMPRIN may be limited to a short time window, comprised between basement membrane degradation allowing direct cell contact and calcified matrix deposition.

Comparison of microstructures between block grafts from the mandibular ramus and calvarium for horizontal bone augmentation of the maxilla: a case series study.

The primary purpose of this clinical study was to compare architectural metric parameters using microcomputed tomography (micro-CT) between sites grafted with blocks harvested from the mandibular ramus and calvarium for horizontal bone augmentation in the maxilla. The second aim was to compare the primary stability of implants placed in both types of block grafts. Ten consecutive healthy partially edentulous patients requiring extensive horizontal bone reconstruction in the maxilla were included. A total of 14 block grafts (7 each from the mandibular ramus and calvarium) were studied. After 4 to 6 months of healing, 41 implants were placed: 24 implants (58.5%) in calvarial (group 1) and 17 (41.5%) in ramus grafts (group 2). A resonance frequency analysis (RFA) was performed to test implant stability. Furthermore, two biopsy specimens were randomly selected for histomorphometric analysis. Micro-CT analyses showed no significant difference in the morphometric parametric values analyzed between groups. Furthermore, RFA also showed no difference between groups. However, slightly higher RFA values were noted for implants placed in ramus grafts. Bone quality, as assessed by micro-CT and histomorphometric analyses, was similar in both ramus and calvarial block grafts. In addition, there was no difference in primary implant stability between groups.

In vivo evaluation of resorbable bone graft substitutes in beagles: histological properties.

Calcium phosphate cement (CPC) is a promising material for use in minimally invasive surgery for bone defect repairs due to its bone-like apatitic final setting product, biocompatibility, bioactivity, self-setting characteristics, low setting temperature, adequate stiffness, and easy shaping into complicated geometrics. However, even though CPC is stable in vivo, the resorption rate of this bone cement is very slow and its long setting time poses difficulties for clinical use. Calcium sulfate dehydrate (CSD) has been used as a filler material and/or as a replacement for cancellous bone grafts due to its biocompatibility. However, it is resorbed too quickly to be optimal for bone regeneration. This study examines the invivo response of a hydroxyapatite (HA), [apatitic phase (AP)]/calcium sulfate (CSD) composite using different ratios in the mandibular premolar sockets of beagles. The HA (AP)/CSD composite materials were prepared in the ratios of 30/70, 50/50, and 70/30 and then implanted into the mandibular premolar sockets for terms of 5 and 10 weeks. The control socket was left empty. The study shows better new bone morphology and more new bone area in the histological and the histomorphometric study of the HA (AP)/CSD in the 50/50 ratio.

Assessment of the effect of low-energy diode laser irradiation on gamma irradiated rats' mandibles.

OBJECTIVE: The purpose of the present study was to evaluate the biostimulative and regenerative effects of low intensity laser irradiation (LILT) (applied before or after initiation of radiotherapy) on gamma irradiated rats' jaw bones. METHODS: Forty eight male Albino rats were equally divided into two groups: group 1, in which the left side of the mandible was subjected to three successive sessions of laser (LILT) prior to whole body gamma radiation (2Gy/3 fractions/week) and group 2, received whole body gamma radiation (2Gy/3 fractions/week) prior to three successive sessions of laser applied to left side. The right side of both groups was used as gamma irradiated non-lased control group. Each group was then subdivided into four equal subgroups (a, b, c, d) according to the time of scarification (3, 7, 14, 21 days respectively). Specimens were subjected to histological, histomorphometric and scanning electron microscopic examinations. RESULTS: Thin irregular bone trabeculae and widened marrow spaces were identified in the control group. The lased sides of groups 1 and 2 demonstrated regular, thick and continuous bone trabeculae. Ultrastructurally, collagen fibres of the control group appeared irregularly arranged and more spaced compared to groups 1 and 2. Normal-sized osteocytic lacunae were seen in the lased groups, as compared to the wide lacunar spaces noted in the control group. Histomorphometric analysis showed a significant increase in the area of bone trabeculae, as well as the width of compact bone, for the lased groups. CONCLUSIONS: LILT seemed to attenuate the radiation-related damage in alveolar bones.

The mandibular ridge oral mucosa model of stromal influences on the endothelial tip cells: an immunohistochemical and TEM study.

This study aimed to evaluate by immunohistochemistry and transmission electron microscopy (TEM) the morphological features of the oral mucosa endothelial tip cells (ETCs) and to determine the immune and ultrastructural patterns of the stromal nonimmune cells which could influence healing processes. Immune labeling was performed on bioptic samples obtained from six edentulous patients undergoing surgery for dental implants placement; three normal samples were collected from patients prior to the extraction of the third mandibular molar. The antibodies were tested for CD34, CD117(c-kit), platelet derived growth factor receptor-alpha (PDGFR-α), Mast Cell Tryptase, CD44, vimentin, CD45, CD105, alpha-smooth muscle actin, FGF2, Ki67. In light microscopy, while stromal cells (StrCs) of the reparatory and normal oral mucosa, with a fibroblastic appearance, were found positive for a CD34/CD44/CD45/CD105/PDGFR-α/vimentin immune phenotype, the CD117/c-kit labeling led to a positive stromal reaction only in the reparatory mucosa. In TEM, non-immune StrCs presenting particular ultrastructural features were identified as circulating fibrocytes (CFCs). Within the lamina propria CFCs were in close contact with ETCs. Long processes of the ETCs were moniliform, and hook-like collaterals were arising from the dilated segments, suggestive for a different stage migration. Maintenance and healing of oral mucosa are so supported by extensive processes of angiogenesis, guided by ETCs that, in turn, are influenced by the CFCs that populate the stromal compartment both in normal and reparatory states. Therefore, CFCs could be targeted by specific therapies, with pro- or anti-angiogenic purposes.

Specific features of mandible structure and elemental composition in the polyphagous amphipod Acanthogammarus grewingkii endemic to Lake Baikal.

BACKGROUND: In crustaceans, several mechanisms provide for the mechanical strength of the cuticular "tools" (dactyli, claws, jaws), which serve to catch and crush food objects. Studies on the mandibles of the endemic Baikal amphipod Acanthogammarus grewingkii by means of electron microscopy and elemental analysis have revealed specific structural features of these mouthparts. METHODOLOGY: The fine structure of the mandible has been studied by means of SEM, TEM, and AFM; methods used to analyze its elemental and phase composition include XEPMA, XPS, SEM-EDS analysis, and XRD. CONCLUSION: Functional adaptations of the mandible in A. grewingkii provide for the optimum combination of mechanical hardness and fracture resistance, which is achieved due to a complex structure and composition of its cutting parts. Teeth of the mandible are covered by a thin layer of silica (10-20 µm). Their epicuticle is characterized by a high density, consists of three layers, and increases in thickness toward the tooth apex. The epicuticle is enriched with Br, while the concentrations of Ca and P reach the peak values in the softer internal tissues of the teeth. These data broaden the view of the diversity of adaptation mechanisms providing for the strengthening of cuticular "tools" in crustaceans.

Computer-aided approach for customized cell-based defect reconstruction.

Computer-aided technologies like computer-aided design (CAD), computer-aided manufacturing (CAM), and a lot of other features like finite element method (FEM) have been recently employed for use in medical ways like in extracorporeal bone tissue engineering strategies. Aim of this pilot experimental study was to test whether autologous osteoblast-like cells cultured in vitro on individualized scaffolds can be used to support bone regeneration in a clinical environment. Mandibular bone defects were surgically introduced into the mandibles of Göttinger minipigs and the scaffold of the defect site was modelled by CAD/CAM techniques. From the minipigs harvested autologous bone cells from the porcine calvaria were cultivated in bioreactors. The cultured osteoblast-like cells were seeded on polylactic acid/polyglycolic acid (PLA/PGA) copolymer scaffolds being generated by rapid prototyping. The bone defects were then reconstructed by implanting these tissue-constructs into bone defects. The postoperative computerized topographic scans as well as the intraoperative sites demonstrated the accurate fit in the defect sites. The individual created, implanted scaffold constructs enriched with the porcine osteoblast-like cells were well tolerated and appeared to support bone formation, as revealed by immunohistochemical and histological analyses. The results of this investigations indicated that the in vitro expanded osteoblast-like cells spread on a resorbable individualized, computer-aided fabricated scaffold is capable of promoting the repair of bone tissue defects in vivo. The shown results warrant further attempts to combine computer modelling and tissue engineering for use in different ways in bone reconstructive surgery.

Evaluación de la anatomía mandibular relacionada con la osteotomía sagital de la rama / Evaluation of mandibular anatomy related to sagittal split ramus osteotomy

La osteotomía sagital de la rama mandibular (SSRO) es una de las técnicas quirúrgicas más frecuentes para corregir las deformidades de la mandíbula. Con el fin de prevenir problemas anatómicos y quirúrgicos, los cirujanos requieren una mayor investigación sobre las estructuras anatómicas relacionadas con la SSRO. El objetivo de este estudio fue investigar las posiciones de la antilingula (AL), la entrada al nervio alveolar inferior (NAI) en la mandíbula y otros puntos de referencia anatómicos en relación con la língula mandibular (L). Fueron estudiadas 70 hemimandíbulas secas. La AL y los demás puntos de referencia y, la posición correspondiente de la L se marcaron en la cara medial y lateral de la rama mandibular respectivamente. Fueron medidas las distancias de la AL, NAI y L en los planos anterior-posterior y superior-inferior con un caliper, y se estableció su relación geométrica. Los resultados mostraron que la AL era perceptible en el 100 por ciento de las caras laterales mandibulares. La mayoría de las ALs se encuentran anterior a la L, con una distancia media de 0,66+/-2,43mm y 0,92+/-2,56 mm y, 4,23+/-2,97 mm y 3,62 +/- 3,14 mm superior a ella (lados derecho-izquierdo respectivamente) (ambos con un valor de p <0,001). Valores similares se observaron en relación con el NAI. No se encontraron diferencias significativas entre los lados derecho e izquierdo, para la mayoría de los parámetros. Los parámetros estudiados pueden asistir a los cirujanos maxilofaciales a determinar la proximidad anatómica del NAI, y reducir al mínimo el riesgo de dañar el nervio y vasos sanguíneos. No recomendamos el uso de la AL como única referencia anatómica cuando se realiza un procedimiento de SSRO.

Sagittal split ramus osteotomy (SSRO) of the mandible is one of the most common surgical techniques to correct mandibular deformities. In order to prevent many surgical anatomical problems, surgeons have found that further investigation of the anatomical structures related to SSRO is needed. This study aims to investigate positions of the antilingula (AL), inferior alveolar nerve (IAN) and other anatomic landmarks in relation to the lingula of dried mandibles. 70 Chilean dried hemimandibles were studied. The AL, others landmarks and the corresponding position of the L were marked on the internal and external aspect of the mandibular ramus respectively. The distances from the AL, IAN and L were measured in the anterior­posterior and the superior­inferior planes using a digital caliper and geometric relationship was established. The results showed the AL was discernible in 100 percent of lateral mandibular rami studied. The most of the AL was found anteriorly to the L with a mean distance of 0.66+/-2.43mm and 0.92+/-2.56mm, and 4.23 +/- 2.97mm and 3.62+/-3.14mm superiorly (right-left sides respectively) (both with p value <0.001). Similar values were seen in relation with IAN. No significant differences were found between the right and left sides, for the majority of parameters. The studied parameters will assist clinicians to determine the anatomical proximity to the IAN, and, minimize the risk of damaging nerver and vessels. We do not recommend the use of antilingula as only anatomical landmark when performing a SSRO procedure.

Age effect in the morphological traits performance for sex determination in human skulls and mandibles / Efecto de la edad en el rendimiento de los rasgos morfológicos para la determinación del sexo en cráneos y mandíbulas humanas

In this study we tested the hypothesis that diagnostic performance of the morphological indicators for sexual dimorphism are reduced as they are applied in skull and mandibles of older subjects. We used 275 adult human skulls, 250 of these with mandible, all subjects with sex and age registry. Sixteen classic morphological indicators of sexual dimorphism were evaluated, this information was compared with the registry and results noted in terms of precision. The best general performance of morphological indicators of sexual dimorphism were recorded in the 31 - 40 and 61 - 70 years, age range groups. Lowest precision ws recorded in the group corresponding to subjects between 21 ­ 30 years. Our results do not support the proposed hypothesis and suggest a progressive and cumulative effect of factors that determine dimorphism expression.

En este estudio testeamos la hipótesis que el rendimiento diagnóstico de los indicadores morfológicos de dimorfismo sexual disminuía al aplicarlos en cráneos y mandíbulas de individuos de mayor edad. Utilizamos 275 cráneos humanos adultos, 250 de los cuales tenían mandíbula, todos con registro de sexo y edad. Se evaluaron 16 indicadores morfológicos clásicos de dimorfismo sexual, estos datos se contrastaron con el registro y los resultados se expresaron en términos de exactitud. El mejor rendimiento general de los indicadores morfológicos de dimorfismo sexual se encontraron en los rangos etarios de 31-40 y de 61-70 años, la menor exactitud se encontró en el grupo correspondiente a individuos de entre 21-30 años. Nuestros resultados no sustentan la hipótesis propuesta y sugieren un efecto progresivo y acumulativo de los factores que determinan la expresión de dimorfismo.

Bone tissue microarchitectural characteristics at dental implant sites. Part 1: identification of clinical-related parameters.

OBJECTIVE: To identify the characteristics of bone tissue microarchitecture by microCT at dental implant bone sites, describing them in terms of clinical parameters. MATERIAL AND METHODS: Forty-six bone implant sites of the maxilla and mandible from 32 volunteers were evaluated by conventional radiographs and CT scans. During the installation of each implant, bone biopsies were removed using a trephine bur at the first drilling to prepare the socket implant. Each sample was evaluated by microCT and dimensional parameters measured. RESULTS: Factor analysis summarized the microparameters into four components, which accounted for 92.8% of the total variance. The identified factors were (1) architecture - variables affecting 3D trabecular bone configuration and organization, (2) density - variables relating to surface/volume ratios and volume/volume ratios, (3) bulk - variables relating to the amount of bone and (4) spacing - variable related to the distance between trabeculae and the quantity and organization of marrow spaces. CONCLUSION: These four summarized factors correspond to clinical and radiographically recognizable parameters used for routine bone quality evaluation for implant treatment planning, which can potentially influence the primary stability of dental implants. The understanding of factors related to bone microarchitecture might reveal important aspects of its mechanical properties, essential for implant success.

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...

Early alveolar bone regeneration in rats after topical administration of simvastatin.

OBJECTIVES: The aim of this study was to ultrastructurally examine the influence of simvastatin on bone healing in surgically created defects in rat mandibles. STUDY DESIGN: Bone defects 0.8 mm in diameter were created in the buccal aspect of first mandibular molar roots and filled with 2.5% simvastatin gel, while the controls were allowed to heal spontaneously. The rats were humanely killed 7, 9, 11, or 14 days postoperatively, and the specimens were processed for scanning and transmission electron microscopy, as well as for colloidal gold immunolabeling of osteopontin. RESULTS: The regenerated alveolar bone in the simvastatin-treated defects presented smaller marrow spaces, and the collagen fibrils were regularly packed exhibiting a lamellar bone aspect. Osteopontin was present through the bone matrix during the wound healing and alveolar bone regeneration. CONCLUSION: The present study provides evidence that a single topical application of 2.5% simvastatin gel improves the quality of the new bone and decreases bone resorption.