Three-dimensional analysis of the alveolar ridge profiles of maxillary central incisors in children for autotransplantation.

BACKGROUND: Sufficient alveolar housing is fundamental to ensure the favorable prognosis of autotransplanted teeth. However, little is known about the alveolar ridge profiles of the anterior maxilla in children. Therefore, this study aimed to investigate the alveolar ridge profiles of the anterior maxilla in growing children. METHODS: A total of 169 Korean children aged 10-13 years old were included in this retrospective study. Demographic data and cone-beam computed tomography scans of 244 maxillary central incisors were collected. For each tooth, the alveolar ridge thickness was determined at 1-, 3-, and 5-mm levels below the cemento-enamel junction. The alveolar process height and labial concavity were also evaluated. Statistical analyses were performed to evaluate differences according to age and sex. RESULTS: The alveolar ridge thickness did not differ according to age. The alveolar ridge thickness in males was significantly greater than that in females among those aged 10 and 11 years. The average alveolar process height was 17.43 ± 2.22 mm. The alveolar process height hardly changed with age from 10-13 years, whereas the alveolar process height of males was significantly greater compared with that of females among those aged 10 years. The labial concavity was approximately 150˚, with no significant differences between age and sex. CONCLUSIONS: Within the limits of this study, the anatomy of the alveolar ridge in the maxillary central incisors showed sufficient capacity as a recipient site for autotransplantation using mandibular premolars, especially in males. These findings serve as a valuable resource for facilitating autotransplantation in children.

Evaluation of Alveolar Bone Dimensions and Root Positioning of Anterior Teeth in the Maxilla.

Buccal bone walls present significant resorption after tooth extraction, possibly related to the smaller bone thickness, length, and the sagittal position of the root, as well as the bone morphology. The goal of the present study was to measure the thickness of the cortical bone of the vestibular and palatal walls in the anterior maxilla by means of CBCT images. Measurements were taken from CBCT scans of 300 maxillary anterior teeth from 50 patients (25 women, 25 men) aged 18 to 30 years. The parameters evaluated included the thickness of the buccal and palatal cortical bone in the cervical, apical, and middle thirds of the root, as well as six specific angular measurements from each tooth. The lateral incisors showed a significant difference in thickness between each of the buccal and palatal thirds, and measurements were also significantly smaller than the central and canine incisors. Bone anatomy is tooth-and location-specific, and thus the sagittal root position within the alveolus influences the regional bone morphology and may explain the gingival zenith position in the anterior maxilla. These specific buccal and palatal anatomic parameters should be carefully taken into consideration for surgical planning and intervention in the esthetic area.

Alveolar bone measurements in magnetic resonance imaging compared with cone beam computed tomography: a pilot, ex-vivo study.

OBJECTIVES: To compare alveolar bone height and width measurements from zero-echo-time MRI (ZTE-MRI) and cone beam CT (CBCT), in human specimens. MATERIAL AND METHODS: Twenty posterior edentulous sites in human cadaver specimens were imaged with CBCT and ZTE-MRI. Bone height and width at 1, 3, 5, 7 and 9 mm from the top of the alveolar ridge was measured by two trained observers in cross-sections of a site where an implant was to be planned. Twenty percent of the sample was measured in duplicate to assess method error and intra-observer reproducibility (ICC). The differences between CBCT and ZTE-MRI measurements were compared (t-test). RESULTS: Inter- and intra-observer reproducibility was >0.90. The method error (average between observers) for bone height was 0.45 mm and 0.39 mm, and for bone width (average) was 0.52 mm and 0.80 mm (CBCT and ZTE-MRI, respectively). The majority of the bone measurement differences were statistically insignificant, except bone width measurements at 5 mm (p ≤ .05 for both observers). Mean measurement differences were not larger than the method error. CONCLUSION: ZTE-MRI is not significantly different from CBCT when comparing measurements of alveolar bone height and width.

Maxillary lateral incisor agenesis is associated with maxillary form: a geometric morphometric analysis.

BACKGROUND AND OBJECTIVE: Agenesis of the maxillary lateral incisor occurs in up to 4% of all individuals and requires multidisciplinary treatment. Its developmental origins, however, are not fully understood. Earlier studies documented genetic factors contributing to agenesis but also an association with craniofacial morphology. In this study, we assessed the association between maxillary morphology and lateral incisor agenesis by a geometric morphometric approach to disentangle the roles of developmental plasticity and genetic factors. MATERIALS AND METHODS: We quantified the maxillary alveolar ridge by 19 two-dimensional landmarks on cross-sectional images of 101 computed tomography scans. We compared the shape and size of the alveolar ridge across patients with unilateral or bilateral agenesis of maxillary lateral incisors and patients with extracted or in situ incisors. RESULTS: The maxillary alveolar ridge was clearly narrower in patients with agenesis or an extracted incisor compared to the control group, whereas the contralateral side of the unilateral agenesis had an intermediate width. Despite massive individual variation, the ventral curvature of the alveolar ridge was, on average, more pronounced in the bilateral agenesis group compared to unilateral agenesis and tooth extraction. CONCLUSIONS: This suggests that pleiotropic genetic and epigenetic factors influence both tooth development and cranial growth, but an inappropriately sized or shaped alveolar process may also inhibit normal formation or development of the tooth bud, thus leading to dental agenesis. CLINICAL RELEVANCE: Our results indicate that bilateral agenesis of the lateral incisor tends to be associated with a higher need of bone augmentation prior to implant placement than unilateral agenesis.

Thickness of the Buccal and Alveolar Bones Overlying Central Incisors: A Radiographic Iraqi Study.

BACKGROUND: Initial bone thickness has a substantial impact on the success of dental implant treatments. The objective of the current study was to analyze the thickness of the buccal and alveolar bone at the central incisors using CBCT in relation to gender and side to determine the anatomical features and choose the best implant treatment option for minimizing the surgical complications. METHODS: One hundred CBCT images were investigated (50 females and 50 males, aged 20 to 50 years old). The buccal bone thickness and alveolar bone thickness were evaluated for right and left sides of each subject at three sites; C: crest (3 mm); M: middle (6 mm); A: apical (9 mm) from the cementoenamel junction. RESULTS: The mean thickness of buccal bone was less than 2 mm on the incisors according to side and gender. Buccal bone thickness revealed a statistically significant difference between right and left sides at the apical point in both females and males with p values of (p ≤ 0.001) and (0.001), respectively. The buccal bone thickness displayed statistically significant differences between genders at all sites. The alveolar thickness demonstrated similar significant differences between genders except for the crest site. CONCLUSIONS: Iraqi participants had about 1 mm buccal bone thickness at 3 mm apical from the CEJ in right and left central incisors with a progressive rise in bone thickness to be less than 2 mm at the apex. Alveolar bone also showed the same increase in bone thickness from crest to apex. Bone thickness was greater in males than females. The present study provided valuable CBCT data on bone thickness of the esthetic maxillary region as a preoperative analysis for establishing an immediate implant treatment plan with aesthetically pleasing long-term outcomes.

Quantitative assessment of the jawbone quality classification: A meta-analysis study.

AIM: Bone quality is evaluated using bone density for qualitative classification, a characteristic that may be delicate to evaluate. Contemporary implantology that relies on modern measurement techniques, needs a more quantitative estimate of the bone quality. MATERIALS AND METHODS: PubMed and EMBASE databases were searched with no time restriction. Clinical and radiographic studies reporting on alveolar ridge dimensions and its parameters in different areas of the dentate and edentulous jaws were included. A meta-analysis was performed using random effect models to report a combined mean for alveolar ridge and its parameters. Meta regression statistical tests were performed in order to identify differences in those outcome parameters. RESULTS: 30 studies were included. The majority of the selected studies (total of 27) used live human subjects and CBCT to analyze alveolar ridge dimensions and its parameters. Using the combined mean obtained from the meta-analysis, a typical portrait of the alveolar ridge was constructed, and a geometrically based quantitative bone classification proposed. The quantitative classification was found to match the existing qualitative classification. CONCLUSION: A geometry-based analysis was constructed that yields valuable insights on the bone type based on its components and on the dynamics of the dentate / edentulous states.

Morphologic analysis of alveolar bone in maxillary and mandibular incisors on sagittal views.

PURPOSE: The aim of this study was to analyze the morphologic features of alveolus in relatively healthy maxillary and mandibular incisors using cone-beam-computed tomography (CBCT). METHODS: CBCT images of 318 patients were retrospectively acquired. Alveolar bone in incisive area was divided into: type 1 (thick), type 2 (relatively thick with mono-plate concavity), type 3 (thin with double-plate concavities), and type 4 (vulnerably thin). Alveolus prevalence and widths were analyzed statistically relative to age, gender, and molar relationship. RESULTS: Prevalence of type 1 alveolus was 78.9% in maxillary central incisors, 15.1% in maxillary lateral incisors, 24.1% in mandibular central incisors, and 5.0% in mandibular lateral incisors. Type 2 alveolus was commonly observed in the maxillary lateral incisors (82.2%), mandibular central incisors (66.2%), and mandibular lateral incisors (87.9%). Prevalence of type 3 and 4 alveoli ranged from 0.0 to 9.4%. As for maxillary central incisors, type 1 was the widest both at the alveolar crest (7.77 ± 0.58 mm) and apical area (9.05 ± 1.86 mm), while type 3 had the lowest width at the apical region (4.08 ± 0.51 mm). Among maxillary central incisors, prevalence of type 1 tended to decrease with age. At all maxillary and mandibular incisor sites, alveolus widths were significantly thicker in males than in females. At maxillary lateral incisor and mandibular incisor sites, prevalence of alveolus type was significantly different among three molar relationships. CONCLUSION: A 4-type classification system was suggested for alveolus morphology in incisive region. Identification of alveolus type might aid in the corresponding treatment.

Morphological integration of the canine region within the hominine alveolar arch.

The early hominin record is characterized by numerous shifts in dental proportions (e.g., canine reduction and megadontia) linked to changes in diet and social behavior. Recent studies suggest that hominins exhibit a reduction in the magnitude of covariation between the anterior and posterior dental components compared with other extant great apes. They point toward, but do not directly test, the relative independence of canine morphology within the hominin alveolar arch. This study focuses specifically on the how the canine region covaries with other regions of the dental arch because the canine region has drastically reduced in size and changed in shape across human evolution. We examine extant primate species most commonly used as a comparative framework for fossil hominin morphology: Gorilla gorilla (n = 27), Pan troglodytes (n = 27), and Homo sapiens (n = 30). We used geometric morphometric methods to test for size and shape covariation between the canine region with other dental regions. We also examined the influence of sexual dimorphism and allometry on intraspecific and interspecific patterns of covariation. The analysis of size and shape covariation between the mandibular canine and other individual tooth regions elucidated complex, species-specific, and sex-specific morphological relationships in the mandibular alveolar arch. There was little evidence to support different patterns of morphological integration between humans on the one hand and nonhuman apes on the other. Canine region morphology was relatively independent from other dental regions across species based on shape and did not significantly covary more with either the incisor or postcanine region in any species. The size correlations between the canine and other dental regions were moderate to high. The species-specific results of this study question the ability to make a priori assumptions about morphological integration in the extant hominin mandibular alveolar arch and its application to the fossil record.

Three-dimensional visualization of the alveolar bone and posterior superior alveolar foramen in gender.

The present study applied a three-dimensional (3D) program to measure the distances from the maxillary sinus floor (MSF) to the lingual and buccal alveolar bone and also to the posterior superior alveolar foramen (PSAF), with the aim of determining differences according to gender. The study also attempted to verify the accuracy of measurements obtained from 3D images by performing comparisons with the results obtained in a preliminary study. The results showed that the alveolar bone length and the MAF-PSAF were generally larger in males than in females. It is also predicted that the accuracy of data obtained from a 3D program will be higher than that of data derived from conventional two-dimensional (2D) images. The accurate measurements obtained in this study are anticipated to prove useful in assessments related to dental implantation and anatomical structures. The fundamental data obtained in this study may also assist in setting the goals of future studies utilizing 3D programs.

CT-based dentulous mandibular alveolar ridge measurements as predictors of crown-to-implant ratio for short and extra short dental implants.

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7 mm), at 1.5 mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy.

Vestibular Alveolar bone height measurement: Accuracy and Correlation between direct and indirect techniques.

Cone Beam Computed Tomography (CBCT) has modified the perspective of dentistry images, providing manipulable threedimensional images with a 1:1 patient:image ratio. Treatments and diagnosis are modified or corroborated by CBCT; however, its accuracy in thin structures such as cortical bone has been subjected to critical review. The aim of this study is to correlate the measurement of vestibular alveolar bone height using direct measurements and measurements performed with cone-beam tomographic images with standard (SD) voxel resolution. Thirty incisor and premolar teeth of patients undergoing open curettage were measured with a high-precision caliper and with Cone Beam Computed Tomography (CBCT) at an SD resolution of 0.16 mm voxels in a 3D Orthophos XG Sirona scanner. Intra-observer evaluation was performed using the intraclass correlation coefficient (ICC). Direct measurements and CBCT measurements were correlated using Pearson correlation (PCC). The mean difference between indirect and direct measurements was 3.15 mm. Paired t test and Pearson Correlation coefficient determined that all measurements differed statistically from each other with p<0.05. With the CT scanner and protocol used in this study, CBCT images do not enable accurate evaluation of vestibular alveolar bone height.

La tomografía de haz cónico (CBCT) ha modificado la perspectiva de la imagenología en odontología que brinda una imagen tridimensional manipulable con una relación 1:1, paciente: imagen. Los tratamientos y diagnósticos se ven modificados o corroborados por el CBCT; sin embargo, la exactitud que presenta en estructuras delgadas como las corticales óseas ha sido sometida a críticas. El objetivo fue correlacionar la medición de la altura del hueso alveolar vestibular mediante mediciones directas y las realizadas con imágenes tomográficas de haz cónico con resolución de vóxel estándar (SD). Treinta dientes incisivos y premolares de pacientes sometidos a un curetaje abierto se midieron con un calibrador de alta precisión y una tomografía computarizada de haz cónico (CBCT) a una resolución SD de 0,16 mm de vóxeles en un escáner 3D Orthophos XG Sirona. La evaluación intraobservador se realizó utilizando el coeficiente de correlación intraclase (ICC), y las mediciones directas y las mediciones CBCT se correlacionaron utilizando la correlación de Pearson (PCC). La diferencia media entre las mediciones indirectas y directas fue de 3,15 mm. La prueba t pareada y el Coeficiente de Correlación de Pearson determinaron que todas las mediciones fueron estadísticamente diferentes entre sí con una p <0.05. Con el escáner de TC y el protocolo utilizado en este estudio, las imágenes CBCT no permiten una evaluación precisa de la altura del hueso alveolar vestibular.

Vestibular Alveolar bone height measurement: Accuracy and Correlation between direct and indirect techniques / Medición de la altura del hueso alveolar vestibular: precisión y correlación entre técnicas directa e indirecta

ABSTRACT Cone Beam Computed Tomography (CBCT) has modified the perspective of dentistry images, providing manipulable threedimensional images with a 1:1 patient:image ratio. Treatments and diagnosis are modified or corroborated by CBCT; however, its accuracy in thin structures such as cortical bone has been subjected to critical review. The aim of this study is to correlate the measurement of vestibular alveolar bone height using direct measurements and measurements performed with conebeam tomographic images with standard (SD) voxel resolution. Thirty incisor and premolar teeth of patients undergoing open curettage were measured with a highprecision caliper and with Cone Beam Computed Tomography (CBCT) at an SD resolution of 0.16 mm voxels in a 3D Orthophos XG Sirona scanner. Intraobserver evaluation was performed using the intraclass correlation coefficient (ICC). Direct measurements and CBCT measurements were correlated using Pearson correlation (PCC). The mean difference between indirect and direct measurements was 3.15 mm. Paired t test and Pearson Correlation coefficient determined that all measurements differed statistically from each other with p<0.05. With the CT scanner and protocol used in this study, CBCT images do not enable accurate evaluation of vestibular alveolar bone height.

RESUMEN La tomografía de haz cónico (CBCT) ha modificado la perspectiva de la imagenología en odontología que brinda una imagen tridimensional manipulable con una relación 1:1, paciente: imagen. Los tratamientos y diagnósticos se ven modificados o corroborados por el CBCT; sin embargo, la exactitud que presenta en estructuras delgadas como las corticales óseas ha sido sometida a críticas. El objetivo fue correlacionar la medición de la altura del hueso alveolar vestibular mediante mediciones directas y las realizadas con imágenes tomográficas de haz cónico con resolución de vóxel estándar (SD). Treinta dientes incisivos y premolares de pacientes sometidos a un curetaje abierto se midieron con un calibrador de alta precisión y una tomografía computarizada de haz cónico (CBCT) a una resolución SD de 0,16 mm de vóxeles en un escáner 3D Orthophos XG Sirona. La evaluación intraobservador se realizó utilizando el coeficiente de correlación intraclase (ICC), y las mediciones directas y las mediciones CBCT se correlacionaron utilizando la correlación de Pearson (PCC). La diferencia media entre las mediciones indirectas y directas fue de 3,15 mm. La prueba t pareada y el Coeficiente de Correlación de Pearson determinaron que todas las mediciones fueron estadísticamente diferentes entre sí con una p <0.05. Con el escáner de TC y el protocolo utilizado en este estudio, las imágenes CBCT no permiten una evaluación precisa de la altura del hueso alveolar vestibular.

[Fluid-solid coupling numerical simulation on ideal porous structure of rat alveolar bone].

Fluid shear stress (FSS) caused by interstitial fluid flow within trabecular bone cavities under mechanical loading is the key factor of stimulating biological response of bone cells. Therefore, to investigate the FSS distribution within cancellous bone is important for understanding the transduction process of mechanical forces within alveolar bone and the regulatory mechanism at cell level during tooth development and orthodontics. In the present study, the orthodontic tooth movement experiment on rats was first performed. Finite element model of tooth-periodontal ligament-alveolar bone based on micro computed tomography (micro-CT) images was established and the strain field in alveolar bone was analyzed. An ideal model was constructed mimicking the porous structure of actual rat alveolar bone. Fluid flow in bone was predicted by using fluid-solid coupling numerical simulation. Dynamic occlusal loading with orthodontic tension loading or compression loading was applied on the ideal model. The results showed that FSS on the surface of the trabeculae along occlusal direction was higher than that along perpendicular to occlusal direction, and orthodontic force has little effect on FSS within alveolar bone. This study suggests that the orientation of occlusal loading can be changed clinically by adjusting the shape of occlusal surface, then FSS with different level could be produced on trabecular surface, which further activates the biological response of bone cells and finally regulates the remodeling of alveolar bone.

The dimension and morphology of alveolar bone at maxillary anterior teeth in periodontitis: a retrospective analysis-using CBCT.

The morphology of the alveolar bone at the maxillary anterior teeth in periodontitis patients was evaluated by cone-beam computed tomography (CBCT) to investigate the distribution of alveolar defects and provide guidance for clinical practice. Ninety periodontitis patients and 30 periodontally healthy individuals were selected to determine the morphology of the alveolar bone at the maxillary anterior teeth according to the degree of bone loss, tooth type, sex and age. The differences in the dimensions between periodontitis patients and healthy individuals were compared, and the distribution of alveolar bone defects was analyzed. A classification system was established regarding the sagittal positions and angulations of the teeth. The buccal residual bone was thicker and the lingual bone was thinner in the periodontitis patients than in the periodontally healthy individuals, and there were differences between the different tooth types, sexes and age subgroups. The buccal undercut was close to the alveolar ridge, while fenestration was reduced and the apical bone height was higher in periodontitis patients than in periodontally healthy individuals. The apical bone height increased with the aggravation of bone loss and age. The proportions of different sagittal positions changed with the aggravation of bone loss. Moreover, the teeth moved more buccally regarding the positions of the maxillary anterior teeth. The morphology of the alveolar bone at the maxillary anterior teeth differed between periodontitis patients and healthy individuals, and the differences were related to the degree of bone loss, tooth type, sex and age.

Comparison of morphological quantitative characteristics of the newly formed alveolar bone after the application of demineralized bone matrix and cortical bone allografts / Comparación de las características morfológicas cuantitativas del hueso alveolar recién formado después de la aplicación de matriz ósea desmineralizada y aloinjertos de hueso cortical

The allografts were used to obtain sufficient alveolar bone tissue for proper dental implant placement. The objective of the present study was to evaluate the morphological and quantitative characteristics (cellular and collagen densities) of the newly formed alveolar bone with the application of cortical bone (CB) and demineralized bone matrix (DBM) allografts. Six samples of alveolar bone tissue from 5 patients (50 ± 6.3 years) were obtained after 6 months of application of the allografts and immediately before the placement of the dental implants. The samples were fixed (buffered formaldehyde, pH7.2), decalcified (EDTA 10 %) and histologically processed (HE and Picro-Sirius) for histologic analysis. Morphological analysis revealed presence of osteocytes and trabeculae in neoformed bone tissue near the allografts and absence of inflammatory and allergic cells; the remnants of CB were located mainly in the periphery of the bone tissue and the remnants of DBM were more incorporated into the tissue. Osteogenitor cells were observed around the remaining material. The cell density was not modified in newly formed bone tissue with the application of both allografts as compared to mature bone tissue. The density of the type I and III collagens present in the osteoids interspersed with the remainder of the materials showed a tendency to increase in the samples treated with DBM. It was concluded that by the histological characteristics observed both grafts were biocompatible, however the bone treated with DBM presented better incorporation and a tendency of increase of the collagen content in the remnant region of the allografts.

Los aloinjertos son utilizados para obtener tejido óseo alveolar apropiado para la colocación correcta del implante dental. El objetivo de este trabajo fue evaluar las características morfológicas y cuantitativas (densidades celulares y de colágeno) del hueso alveolar recién formado con la aplicación de aloinjertos de hueso cortical (CB) y matriz desmineralizada de hueso (DBM). Seis muestras de tejido óseo alveolar fueron obtenidas de 5 pacientes (50 ± 6,3 años) después de 6 meses de aplicación de los aloinjertos e inmediatamente antes de la colocación de los implantes dentales. Las muestras fueron fijadas (formaldehído tamponado, pH 7,2), descalcificadas (EDTA al 10%) y procesadas histológicamente (HE y Picro-Sirius) para el análisis histológico. El análisis morfológico reveló la presencia de osteocitos y trabéculas en el tejido óseo neoformado cerca de los aloinjertos y la ausencia de células inflamatorias y alérgicas; los remanentes de CB se ubicaron principalmente en la periferia del tejido óseo y los remanentes de DBM se incorporaron más en el tejido. Se observaron células osteogenitoras alrededor del material restante. La densidad celular no se modificó en el tejido óseo recién formado con la aplicación de ambos aloinjertos en comparación con el tejido óseo maduro. La densidad de los colágenos de tipo I y III presentes en los osteoides intercalados con el resto de los materiales mostró una tendencia a aumentar en las muestras tratadas con DBM. Se concluyó que, debido a las características histológicas observadas, ambos injertos fueron biocompatibles, sin embargo, el hueso tratado con DBM presentó una mejor incorporación y una tendencia al aumento del contenido de colágeno en la región remanente de los aloinjertos.

The 3-dimensional zone of the center of resistance of the mandibular posterior teeth segment.

INTRODUCTION: We sought the 3-dimensional (3D) zone of the center of resistance (ZCR) of mandibular posterior teeth groups (group 1: first molar; group 2: both molars; group 3: both molars and second premolar; group 4: both molars and both premolars) with the use of 3D finite element analysis. METHODS: 3D finite element models comprised the mandibular posterior teeth, periodontal ligament, and alveolar bone. In the symmetric bilateral model, a 100-g midline force was applied on a median sagittal plane at 0.1-mm intervals to determine the anteroposterior and vertical positions of the ZCR (where the applied force induced translation). The most reliable buccolingual position of the ZCR was then determined in the unilateral model. The combination of the anteroposterior, vertical, and buccolingual positions was defined as the ZCR. RESULTS: The ZCRs of groups 1-4 were, respectively, 0.48, 0.46, 0.50, and 0.53 of the mandibular first molar root length from the alveolar crest level and located slightly distobuccally at anteroposterior ratios of 2:3.0, 2:2.3, 2:2.4, and 2:2.5 to each sectional arch length and at buccolingual ratios of 2:1.5, 2:1.1, 2:1.6, and 2:2.4 to the first molar's buccolingual width. CONCLUSIONS: The ZCR can be a useful reference for 3D movement planning of mandibular posterior teeth or segments.

Morphometric predictors of lingual undercut depth in the posterior mandible and their relevance to immediate dental implant insertion: recommendations for CBCT / Predictores morfométricos de la profundidad de la «undecurt¼ lingual en la parte posterior de la mandíbula y su relevancia para la inserción inmediata de implantes dentales: recomendaciones para la CBCT

Deep lingual undercut (LU) is commonly encountered in the posterior mandible, and is considered a risk factor in dental implants. In this study we investigated the value of data extracted from OPGs in predicting LU depth. Such predictors might be valuable in reducing the chance of lingual plate perforation (LPP) by recommending CBCTs prior to dental implant insertion when deep LU is anticipated We aimed at assessing the following variables as potential predictors of LU depth: 1) alveolar process height (measured on OPGs), 2) alveolar process width (measured on CBCTs), and 3) the distance from apical region of dental alveoli to superior margin of IAN canal (measured on OPGs). 128 CBCTs and corresponding OPGs of posterior mandibles of 128 patients (70 females, 58 males; age range=18-87 years, mean age=45.8 years, SD=17.0 years) were used. Only dentate sites of lower first (LM1) and second molars (LM2) were considered. Four predictors of LU depth were found, the strongest was the ratio between alveolar process width (which could be assessed clinically) and alveolar process height as measured on OPGs (r=.454 at LM1 site, r=.592 at LM2 site). Predictors derived from OPG measurements might be valuable in anticipating LU depth and might be more valuable when combined with alveolar process width (which might be assessed clinically). We recommend considering the suggested predictors in assessing the need of CBCT prior to immediate dental implant insertion in posterior mandible.

El socavado lingual profundo (SLU) se encuentra comúnmente en la porción posterior de la mandíbula y es considerado un factor de riesgo en los implantes dentales. En este estudio, investigamos el valor de los datos extraídos de los OPG para predecir la profundidad del SLU. Dichos predictores podrían ser valiosos para reducir la posibilidad de perforación de la placa lingual (PPL) recomendando CBCT antes de la inserción del implante dental cuando se anticipa un SLU. El objetivo consistió en evaluar las siguientes variables como posibles predictores de profundidad de SLU: 1) altura del proceso alveolar (medida en OPG), 2) ancho del proceso alveolar (medido en CBCT) y 3) la distancia desde la región apical de los alvéolos dentales al margen superior del canal IAN (medido en OPG). Se utilizaron 128 CBCT y las OPG correspondientes de mandíbulas de 128 pacientes (70 mujeres, 58 hombres; rango de edad = 18-87 años, edad media = 45,8 años, SD = 17,0 años). Sólo se consideraron los sitios dentados de los primeros molares inferiores (LM1) y los segundos molares inferiores (LM2). Se encontraron cuatro predictores de profundidad de SLU, el más fuerte fue la relación entre el ancho del proceso alveolar (que podría evaluarse clínicamente) y la altura del proceso alveolar medida en OPG (r = 0,454 en el sitio LM1, r = 0,592 en el sitio LM2). Los predictores derivados de las mediciones de OPG podrían ser valiosos para anticipar la profundidad de SLU y podrían ser más valiosos cuando se combinan con el ancho del proceso alveolar (que podría evaluarse clínicamente). Recomendamos considerar los factores predictivos sugeridos para evaluar la necesidad de CBCT antes de la inserción inmediata del implante dental en la porción posterior de la mandíbula.

Anatomical analyses for maxillary sinus floor augmentation with a lateral approach: A cone beam computed tomography study.

BACKGROUND: Various anatomical references and structures should be analyzed prior approaching a surgery in the maxillary sinus. The objective of the present study was to evaluate the anatomical structures and references involved in sinus floor elevation with a lateral approach. MATERIALS AND METHODS: Seventy-five patients planned for sinus floor elevation were included in the study. Eighty-eight maxillary sinuses were evaluated using cone beam computed tomographies (CBCTs). The nasal floor was used as main reference (X) and sinus mucosa width, bone crest height, palatal-nasal recess angle (PNR), sinus width at the level of the nasal floor, distance from the nasal floor to the base of the sinus (X-F), position of the posterior superior alveolar artery (PSAA height) and diameter (PSAA diameter), lateral bone wall width at 3mm (LW 3mm) and 9mm (LW 9mm) from the base of the sinus (F), patency of the ostium (OP), and presence and position of septa have been evaluated. RESULTS: The mean dimensions and standard deviations were the following: mucosa thickness was 2.0±1.4mm, bone crest height 2.8±1.4mm, distance X-F 8.3±1.9mm, PNR angle 135.5±23.1, sinus width 12.6±4.2mm, X-F 8.3±1.9mm, PSAA height 14.4±2.9mm, PSAA diameter 1.1±0.4mm, LW 3mm 1.5±1.2, LW 9mm 1.3±0.6mm, OP 1.9±0.4mm. Septa were present in 19.3% of the sinuses evaluated and were located mostly in the molar region. CONCLUSIONS: In conclusion, the analysis of the CBCT before sinus floor elevation allows the identification of anatomical structures and references that might be used for the planning of the surgical approach, aiming to improve the outcome of the treatment and to avoid possible complications.

Anatomical Location of the Infraorbital Foramen in Infant Dry Skulls: Implications for Cleft Surgery.

BACKGROUND: Infraorbital foramen (IOF) is an important anatomical landmark in cleft lip surgery. The location of IOF within the maxilla of infants is different from adults. However, little information about anatomy of IOF in infants exists in the literature. This study aims to determine the location of IOF in infant dry skulls based on key surgical landmarks. METHODS: All dry skulls under age 2 years old were selected from the Hamann-Todd Human Osteological Collection at the Cleveland Museum of Natural History (Cleveland, OH). Specimens without cranial bones or complete maxilla were excluded. Seven anatomical measurements were taken on each side of the face for each individual skull (14 measurements for each skull). Anatomical landmarks used for the measurements included infraorbital rim, aperture piriformis, alveolar ridge, zygomaticomaxillary buttress, anterior nasal spine (ANS), and inferolateral corner of the aperture piriformis. RESULTS: Twenty-seven halves of 14 dry skulls were included in the final analysis. The mean age of specimens was 0.57 years. Mean distances from infraorbital foramen to infraorbital rim, aperture piriformis, alveolar ridge, zygomaticomaxillary, and ANS buttress were 4.11 ±â€Š0.82, 9.4 ±â€Š1.62, 12.7 ±â€Š2.71, 11.7 ±â€Š1.54, and 18.4 ±â€Š2.11 mm, respectively. CONCLUSION: This study also shows that the infraorbital foramen in infants is located at the level of the ANS or within 2 mm higher and that the distance between the infraorbital rim and foramen is only 3 to 4 mm. These findings should be applied to the cleft population with discretion.