Optimal microimplant sites in the mandibular retromolar area: mesh analysis of cortical bone thickness and density in CBCT images / Sitios de microimplantes óptimos en el área retromolar mandibular: análisis de malla del grosor y densidad del hueso cortical en imágenes CBCT

SUMMARY: This study was performed to identify optimal microimplant sites in the mandibular retromolar area by measurement and analysis of cortical bone thickness and density. Forty-nine records of cone-beam computed tomography were selected from 173 patients. Invivo 5.2 software was used to measure the thickness and density of 25 sites on a mesh in the mandibular retromolar area. Pearson correlation, Spearman correlation, and binary logistic regression analyses were performed to explore correlations between retromolar measurements and patient characteristics. The LSD test was used to identify optimal microimplant sites in this area. One-way ANOVA, with post hoc SNK test, was used to compare optimal microimplant sites among the retromolar area, the distobuccal bone of the second molar, and a location between the first and second molars. The mean thickness and density of mandibular retromolar cortical bone were 2.35 ± 0.76 mm and 530.49 ± 188.83 HU, respectively. In the mandibular retromolar area, the thickness and density of cortical bone increased from the lingual to buccal sides, and from the distal to mesial. Among 25 sites, S5C1 had the greatest thickness and density; it exhibited greater thickness and density, compared with the distobuccal bone of the second molar and the site between the first and second molars. For distal uprighting of mesially tipped molars, we recommend placement of microimplants into the retromolar distobuccal site; for distalization of mandibular dentition, we recommend placement of microimplants into the retromolar mesiobuccal site (S5C1) or 2 mm from the mesial direction of the second molar distobuccal site (B).

RESUMEN: Este estudio se realizó para identificar los sitios óptimos de microimplantes en el área retromolar mandibular mediante la medición y el análisis del grosor y la densidad del hueso cortical. Se seleccionaron 49 registros de tomografía computarizada de haz cónico de 173 pacientes. Se utilizó el software Invivo 5.2 para medir el grosor y la densidad de 25 sitios en una malla en el área retromolar mandibular. Se realizaron análisis de correlación de Pearson, correlación de Spearman y regresión logística binaria para explorar las correlaciones entre las mediciones retromolares y las características del paciente. La prueba de LSD se utilizó para identificar los sitios óptimos de microimplantes en esta área. Se utilizó ANOVA unidireccional, con prueba SNK post hoc, para comparar los sitios óptimos de microimplante entre el área retromolar, el hueso distobucal del segundo molar y una ubicación entre el primer y el segundo molar. El grosor y la densidad medios del hueso cortical retromolar mandibular fueron 2,35 ± 0,76 mm y 530,49 ± 188,83 HU, respectivamente. En el área retromolar mandibular, el grosor y la densidad del hueso cortical aumentaron desde el lado lingual al bucal y desde el distal al mesial. Entre los 25 sitios, S5C1 se determinó el mayor espesor y densidad; presentó mayor grosor y densidad, en comparación con el hueso distobucal del segundo molar y el sitio entre el primero y el segundo molar. Para rectificación distal de molares con punta mesial, recomendamos la colocación de microimplantes en el sitio retromolar bucal; para la distalización de la dentición mandibular, recomendamos la colocación de microimplantes en el sitio retromolar mesiobucal (S5C1) o 2 mm desde la dirección mesial del sitio distobucal del segundo molar (B).

Micro-implanted-anchorage safety: cortical bone thickness in the maxillary posterior region of skeletal class II malocclusion / Seguridad en el micro-implante de anclaje: espesor del hueso cortical en la región posterior del maxilar en maloclusión de clase esquelética tipo II

Cone Beam Computed Tomography (CBCT) measurement of cortical bone thickness and implantation angle in the maxillary posterior region was used to provide reference for the safety of Micro-Implanted-Anchorage (MIA) implantation in skeletal class II malocclusion. Twenty samples of CBCT images were collected from orthodontics patients (ages, 12-40 years) in Shanxi Medical University Stomatological Hospital, the thickness of cortical bone was measured at 45°, 60° and 90° from the alveolar crest, being at 4 mm, 6 mm and 8 mm, respectively. SPSS17.0 statistical software was used to analyze the data, and the one-way ANOVA and LSD method were compared. There was a significant difference in the thickness of the cortical bone obtained by implanting MIA at the same height of different angle (P≤0.05). The greater the inclination angle of the implanted MIA, the thicker the cortical bone. Also, the higher the implant site, the thicker the cortical bone thickness. Finally, the greater the thickness of the cortical bone in the maxillary posterior region of skeletal class II malocclusion, the greater the thickness of the cortical bone. At the same implantation height, implanted MIA with a tilt angle of 45º to 60º, 90º to obtain the best cortical bone thickness.

La medición del grosor del hueso cortical y del ángulo de implantación en la región posterior del maxilar por tomografía computarizada de haz cónico (TCHC) se utilizó para proporcionar una referencia para la implantación y el anclaje seguros de un Micro-Implante de Anclaje (MIA) en la maloclusión de clase esquelética tipo II. Veinte muestras de imágenes de TCHC fueron obtenidas de pacientes de ortodoncia (12-40 años) en el Hospital Estomatológico de la Universidad Médica de Shanxi. Se midió el grosor del hueso cortical a 45°, 60° y 90° de la cresta alveolar, encontrándose a 4 mm, 6 mm y 8 mm, respectivamente. Se utilizó el software estadístico SPSS 17.0 para analizar los datos, y se compararon con los métodos ANOVA y LSD de un factor. Hubo una diferencia significativa en el grosor del hueso cortical obtenido al implantar el MIA a la misma altura en diferentes ángulos (P <0,05). Cuanto mayor es el ángulo de inclinación del MIA implantado, más grueso es el hueso cortical. También, cuanto más alto es el sitio del implante, más grueso es el grosor del hueso cortical. Finalmente, cuanto mayor sea el grosor del hueso cortical en la región posterior del maxilar, en la maloclusión de clase esquelética tipo II, mayor será el grosor del hueso cortical.

Quantitation of Mandibular Symphysis Bone as Source of Bone Grafting: Description in Class I and Class III Skeletal Conditions.

The aim of this study was to quantify the cortical and cancellous bone in the mandibular symphysis and relate it to the teeth and to the skeletal class. A descriptive study was conducted using cone beam computerized tomography (CBCT). Class I and class III subjects were included, defined according to dental occlusion and cephalogram results. Linear measurements were taken on the CBCT of the mandibular canines, lateral incisors, and central incisors, where the analysis was related to the axial and apical axes considering the bone in relation to the dental area. With previous definitions, an observer took 2 measurements of the height of the mandibular symphysis, cortical bone of the buccal and lower region, and thickness of cancellous bone at different levels; the correlation coefficient between the first and second measurement was 0.99 and presented P = .001. The results were analyzed with analysis of variance and Tukey's honest significant difference test, with P < .05 being statistically significant. The symphysis height was significantly greater in class III subjects. The cortical bone was an average 1.67 ± 0.44 mm in vertical distance in the skeletal class I group and 1.74 ± 0.47 mm in the class III group. The cancellous bone had an average width of 5.03 ± 1.94 mm in the skeletal class I group and 4.74 ± 2.05 mm in the class III group. It was observed that cancellous bone was significantly thicker at the incisor level than at the canine level. There were anatomical differences between skeletal class I and class III subjects, although the clinical significance may be questionable. With the values from these analyses, it may be concluded that there are no significant differences in quantitation of the cortical and cancellous bone in the anterior mandibular symphysis.

Ibuprofen before Exercise Does Not Prevent Cortical Bone Adaptations to Training.

Using a nonsteroidal anti-inflammatory drug (NSAID) before a single bout of mechanical loading can reduce bone formation response. It is unknown whether this translates to an attenuation of bone strength and structural adaptations to exercise training. PURPOSE: This study aimed to determine whether nonsteroidal anti-inflammatory drug use before exercise prevents increases in bone structure and strength in response to weight-bearing exercise. METHODS: Adult female Wistar rats (n = 43) were randomized to ibuprofen (IBU) or vehicle (VEH) and exercise (EX) or sedentary (SED) groups in a 2 × 2 (drug and activity) ANCOVA design with body weight as the covariate, and data are reported as mean ± SE. IBU drops (30 mg·kg BW) or VEH (volume equivalent) were administered orally 1 h before the bout of exercise. Treadmill running occurred 5 d·wk for 60 min·d at 20 m·min with a 5° incline for 12 wk. Micro-CT, mechanical testing, and finite element modeling were used to quantify bone characteristics. RESULTS: Drug-activity interactions were not significant. Exercise increased tibia cortical cross-sectional area (EX = 5.67 ± 0.10, SED = 5.37 ± 0.10 mm, P < 0.01) and structural estimates of bone strength (Imax: EX = 5.16 ± 0.18, SED = 4.70 ± 0.18 mm, P < 0.01; SecModPolar: EX = 4.01 ± 0.11, SED = 3.74 ± 0.10 mm, P < 0.01). EX had increased failure load (EX = 243 ± 9, SED = 202 ± 7 N, P < 0.05) and decreased distortion in response to a 200-N load (von Mises stress at tibia-fibula junction: EX = 48.2 ± 1.3, SED = 51.7 ± 1.2 MPa, P = 0.01). There was no effect of ibuprofen on any measurement tested. Femur results revealed similar patterns. CONCLUSION: Ibuprofen before exercise did not prevent the skeletal benefits of exercise in female rats. However, exercise that engenders higher bone strains may be required to detect an effect of ibuprofen.

Morphometric evaluation of the early stages of healing at cortical and marrow compartments at titanium implants: an experimental study in the dog.

OBJECTIVE: To study the early sequential stages of tissue composition in the cortical and marrow compartments of the alveolar bone crest at implants with a moderately rough surface. MATERIALS AND METHODS: Three month after tooth extraction in 12 Labrador dogs, full-thickness flaps were elevated in the edentulous region of the right side of the mandible and one implant was installed. The flaps were sutured to allow a fully submerged healing. The timing of the installations in the left side of the mandible and of sacrifices were scheduled in such a way to obtained biopsies representing the healing after 5, 10, 20, and 30 days. Ground sections (n = 6 per each healing period) were prepared, and the percentages of osteoid/new bone, old bone, new soft tissues (provisional matrix and primitive marrow), mature bone marrow, vessels, and other tissues (bone debris/particles and clot) were evaluated laterally to the implant surface up to a distance of about 0.4 mm from it. RESULTS: Osteoid/new bone was found after 5 days at percentages of 10.8 ± 4.3% at the marrow and 0.6 ± 0.6% at the cortical compartments. After 30 days, these percentages increased up to 56.4 ± 4.0% and 23.3 ± 6.1%, respectively. Old parent bone was resorbed between 5 and 30 days from 28.7 ± 10.9% to 14.9 ± 3.4% at the marrow (~48% of resorption) and from 81.2 ± 9.4% to 67.6 ± 5.6% at the cortical (~17% of resorption) compartments. All differences were statistically significant. CONCLUSION: Bone apposition to an implant surface followed a significantly different pattern in the compact and the marrow compartments around the implants. While in the compact compartments, bone apposition had to develop through the BMUs following resorption, it developed in very dense layers through an early apposition in the marrow compartments.

Structural differences in cortical shell properties between upper and lower human fibula as described by pQCT serial scans. A biomechanical interpretation.

This study describes the structural features of fibula cortical shell as allowed by serial pQCT scans in 10/10 healthy men and women aged 20-40years. Indicators of cortical mass (mineral content -BMC-, cross-sectional area -CSA-), mineralization (volumetric BMD, vBMD), design (perimeters, thickness, moments of inertia -MIs-) and strength (Bone Strength Indices, BSIs; polar Strength-Strain Index, pSSI) were determined. All cross-sectional shapes and geometrical or strength indicators suggested a sequence of five different regions along the bone, which would be successively adapted to 1. transmit loads from the articular surface to the cortical shell (near the proximal tibia-fibular joint), 2. favor lateral bending (central part of upper half), 3. resist lateral bending (mid-diaphysis), 4. favor lateral bending again (central part of the lower half), and 5. resist bending/torsion (distal end). Cortical BMC and the cortical/total CSA ratio were higher at the midshaft than at both bone ends (p<0.001). However, all MIs, BSIs and pSSI values and the endocortical perimeter/cortical CSA ratio (indicator of the mechanostat's ability to re-distribute the available cortical mass) showed a "W-shaped" distribution along the bone, with maximums at the mid-shaft and at both bone's ends (site effect, p<0.001). The correlation coefficient (r) of the relationship between MIs (y) and cortical vBMD (x) at each bone site ("distribution/quality" curve that describes the efficiency of distribution of the cortical tissue as a function of the local tissue stiffness) was higher at proximal than distal bone regions (p<0.001). The results from the study suggest that human fibula is primarily adapted to resist bending and torsion rather than compression stresses, and that fibula's bending strength is lower at the center of its proximal and distal halves and higher at the mid-shaft and at both bone's ends. This would favor, proximally, the elastic absorption of energy by the attached muscles that rotate or evert the foot, and distally, the widening of the heel joint and the resistance to excessive lateral bending. Results also suggest that biomechanical control of structural stiffness differs between proximal and distal fibula.

Location and classification of Canalis sinuosus for cone beam computed tomography: avoiding misdiagnosis.

The aim of this study was to assess the presence, location and, multiplanar distance of the canalis sinuosus (CS) between the incisive foramen and the anterior maxillary alveolar ridge using cone beam computed tomography (CBCT). Therefore, 500 CBCT maxillary images obtained from male and female patients aged 20 to 80 years were selected to assist in the dental treatment. Low-quality tomographic images were discarded. All images were captured with the i-CATTM Classic tomograph and assessed using the XoranCatTM software. The axial sections were analyzed at the incisive foramen in order to verify the CS presence in laterality and location. Furthermore, linear measurements of the nasal cavity floor, buccal cortical bone, and alveolar ridge crest were made. All the collected data were statistically analyzed. Results show a variation of the CS in relation to the classification and distance of anatomical structures, but no significant difference between the right and left sides. It should be highlighted that CBCT is necessary before invasive procedures in order to preserve important anatomical structures. In conclusion, the location of the CS varies in relation to the alveolar ridge crest and buccal cortical bone, assuming that it is going to be located by the upper lateral incisor palatine.

Hueso cortical en sínfisis mandibular de sujetos de clase I / Cortical bone in mandibular symphysis of class I subjects

El objetivo fue evaluar la relación de tejido óseo cortical presente en el sector anterior y posterior de sínfisis mandibular. Se seleccionaron 18 sujetos clase I dentaria y esqueletal, de ambos sexos, a partir de una tomografía computarizada de haz cónico para analizar morfométricamente en base a la posición de los dientes canino, incisivo lateral e incisivo central de ambos lados; se analizó la distancia vertical desde el ápice dentario hasta el punto más inferior del margen mandibular y la distancia anteroposterior en dos niveles inferiores del ápice (5 mm y 10 mm), donde se identificó el grosor de hueso cortical. El análisis de datos fue realizado con la prueba ANOVA considerando un valor de p<0,05. Se observó que el hueso cortical es de mayor tamaño en la cortical lingual que la cortical bucal con casi 1 mm de diferencia; la cortical inferior fue la de mayor tamaño; no se observaron diferencias en las mediciones realizadas para cada diente. Se concluye que el hueso cortical es de menor tamaño en el sector bucal al compararse con el lingual e inferior; se debe explorar los alcances quirúrgicos de este hallazgo.

The aim of this research was to evaluate the relation between the cortical bone in the anterior and posterior area of the mandible. Were selected 18 subjects, male and female, with dental and skeletal class I; in all of them was realized a cone beam computed tomography to make a morphometric analysis in agreed with de canine, lateral incisor and central incisor in the right and left, side. Was analyzed the distance in cortical area in a line from the dental apex and the horizontal line was obtained 5 mm and 10 mm from the dental apex; statistical significance was obtained by ANOVA considering a p value <0.05. Was observed that the cortical bone is thicker in the lingual side than the buccal side (1 mm diference approximately); the low cortical presented bigger size than anterior or posterior cortical bone; was not observed statistical differences between bone related to teeth. Its concluded that the buccal cortical bone is lower than lingual cortical bone; it is necessary an analysis about the surgical implications.

Location and classification of Canalis sinuosus for cone beam computed tomography: avoiding misdiagnosis

Abstract The aim of this study was to assess the presence, location and, multiplanar distance of the canalis sinuosus (CS) between the incisive foramen and the anterior maxillary alveolar ridge using cone beam computed tomography (CBCT). Therefore, 500 CBCT maxillary images obtained from male and female patients aged 20 to 80 years were selected to assist in the dental treatment. Low-quality tomographic images were discarded. All images were captured with the i-CATTM Classic tomograph and assessed using the XoranCatTM software. The axial sections were analyzed at the incisive foramen in order to verify the CS presence in laterality and location. Furthermore, linear measurements of the nasal cavity floor, buccal cortical bone, and alveolar ridge crest were made. All the collected data were statistically analyzed. Results show a variation of the CS in relation to the classification and distance of anatomical structures, but no significant difference between the right and left sides. It should be highlighted that CBCT is necessary before invasive procedures in order to preserve important anatomical structures. In conclusion, the location of the CS varies in relation to the alveolar ridge crest and buccal cortical bone, assuming that it is going to be located by the upper lateral incisor palatine.