Gingival Biotype and Its Relationship With the Maxillary Membrane and Lateral Wall Thickness.

The purpose of this study was to analyze the risk of the maxillary sinus lift technique and the correlation between the thickness of the gingiva, maxillary sinus membrane, and the maxillary sinus lateral wall. Cone-beam computerized tomograhy (CBCT) records of 32 adult dentate patients (10 male/22 female) were analyzed. The gingival thickness records of the dental units were compared with the thickness measurements of the membrane and lateral wall of the maxillary sinus. The gingival biotypes varied between 1.1 mm (thin) and 1.6 mm (thick), with a small association with sex. The thickness of the sinus membrane presented a small association between sexes (0.2 mm, female/0.3 mm, male) and gingival biotypes (Cohen d = .52). The lateral wall presented a weak association between the biotypes (1.3 mm, thin/1.1 mm, thick). There was also no correlation between the membrane and lateral wall (r = -.22). The volume dimension related to the graft area of the sinus was 4 mm3 for men and 5 mm3 for women. There was a weak correlation of gingival thickness compared with membrane thickness and lateral wall of the sinus (r = .304/r = -.31). Gingival thickness does not appear to be a reliable thickness predictor of the membrane or lateral wall of the maxillary sinus. The analysis of maxillary sinus anatomical structures through CBCT is the most reliable technique to identify the thickness of the membrane and lateral wall of the maxillary sinus before surgery. We believe that new studies are necessary to confirm our findings.

Buccal injection of articaine to anesthetize the palatal mucosa.

Buccal and palatal injections are required for administration of anesthetic agents before maxillary tooth extractions, but palatal injections are painful for patients. Studies suggest that the palatal injection can be eliminated when articaine is delivered as a local anesthetic agent via buccal injection, but the anatomical mechanism for this effectiveness remains unclear. The objective of this study was to explore the potential mechanism by which buccal infiltration results in palatal anesthesia. The study approach included examining cadaveric specimens and investigating the pharmacologic properties of articaine. Twenty-eight formalin-fixed cadaveric hemimaxillae were dissected and sectioned into anterior, premolar, and molar regions. The maxillary sections were measured in 3 planes: inferior, middle, and superior. Buccal cortical plate (BCP), palatal cortical plate (PCP), and total buccopalatal (TBP) thickness were independently evaluated by 2 measurers using standard digital calipers. Statistical analysis of regional maxillary thickness measurements was achieved via 2-way analysis of variance. Measurements of BCP and PCP thickness revealed no statistically significant differences along the maxillae (P > 0.05). Both the BCP and PCP mean values were significantly less than the TBP measurement (P < 0.0001). In all 3 regions, the mean TBP thickness in the superior plane was significantly greater than that of the inferior plane (P < 0.05). The mean TBP thickness was significantly greater in the molar and premolar regions than in the anterior region (P < 0.05). The mean BCP measurements were significantly lesser in the maxillary premolar and molar regions than in the corresponding mandibular regions (P < 0.0001). The pharmacologic properties of articaine, which is capable of diffusing greater distances than other local anesthetics, coupled with the uniformly thin, cancellous maxillary bone, provide a plausible explanation for the success of palatal anesthesia achieved through buccal infiltration of articaine, obviating the need for a palatal injection.

In-vitro comparison of different palatal sites for orthodontic miniscrew insertion: Effect of bone quality and quantity on primary stability.

INTRODUCTION: This experiment was undertaken to assess the primary stability of orthodontic miniscrews inserted at different sites in human cadaveric palatal bone for temporary skeletal anchorage, and to determine the effect of bone quality and quantity on their primary stability using microcomputed tomography imaging. METHODS: A total of 10 cadaveric maxillary hard palates were used for insertion of 130 orthodontic miniscrews (VectorTAS; Ormco, Orange, Calif; length, 6 mm; diameter, 1.4 mm). Upon insertion, maximal insertion torque (IT) was recorded. Imaging (microcomputed tomography) was performed before and after insertion for assessment of bone quality and quantity parameters (bone mineral density [BMD], bone thickness [BT], and length of screw engagement [LSE]). Differences in each parameter were assessed at the various insertion sites. Correlations between IT and measurements of BMD, BT, and LSE were evaluated. RESULTS: Significant differences (P < 0.001) were found among insertion sites for IT, BT, and LSE, but not for BMD (P = 0.004). Correlations were found between IT and BMD (rs = 0.42; P < 0.001), IT and BT (rs = 0.58; P < 0.001), and IT and LSE (rs = 0.58; P < 0.001). Most perforations of miniscrews into the nasal cavity occurred posterior to the permanent second premolars. CONCLUSIONS: The primary stability of orthodontic miniscrews in the palate is affected by bone quality and quantity, with higher primary stability obtained anterior to the second premolars and parasagittally at the level of the permanent first molars.

A Three-dimensional Analysis of Zygomatic Symmetry in Normal, Uninjured Faces.

Current approaches to facial reconstruction are based on the assumption of facial symmetry, though this has yet to be established in the literature. Through quantitative and qualitative analysis, symmetry of normal, male faces is examined here using the zygomatic complex as a bellwether for the rest of the facial skeleton. Three-dimensional models reconstructed from the computed tomography scans of 30 adult male patients displaying normal facial skeletal anatomy were analyzed. Seven zygomatic landmarks were identified on all craniofacial models, and asymmetry scores were calculated based on the average deviation distance upon reflection of 1 hemiface across the midfacial plane. Deviation maps were then generated for each zygomatic pair to enable visualization of the asymmetry. All landmarks displayed a slight (<3 mm) deviation from perfect symmetry, and analysis of zygomatic form asymmetry revealed an average of 0.4 mm of surface deviation between hemifaces. The presence of such slight asymmetries in the zygoma warrants further investigation as to the clinical relevance of such skeletal asymmetries from both an esthetic and biomechanical consideration to provide insight as to the proper approach to zygomatic restoration in cases of zygomatic fracture.

ANATOMICAL VARIATIONS OF THE GREATER PALATINE NERVE IN THE GREATER PALATINE CANAL.

The greater palatine nerve and the greater palatine canal are common sites for maxillary anesthesia during dental and maxillo-facial procedures. The greater palatine nerve is thought to course as a single trunk through the greater palatine canal, branching after its exit from the greater palatine foramen. We describe intra-canalicular branching variations of the greater palatine nerve found in 8 of 20 embalmed dissection specimens. Such variation is previously unreported in the literature. We characterize the variations in branching pattern and discuss the possible implications for clinical practice.

Ultrasound-guided greater palatine nerve block: a case series of anatomical descriptions and clinical evaluations.

BACKGROUND: Greater palatine nerve (GPN) block is commonly performed for maxillary and palatal anesthesia by using bony landmarks. Ultrasound (US) can be used to consistently identify greater palatine foramen (GPF) as a defect in the bony palate enabling US-guided injections near the foramen. METHODS: We scanned and injected 16 undissected well-embalmed hemisectioned cadaveric heads after excluding major anatomical malformations. A linear high-frequency hockey stick probe (7-13 MHz) positioned in long axis to the hard palate visualized GPF as a discontinuity in the hard palate. US-guided injections of 0.1 mL India ink were made in an oblique plane. Specimens were dissected immediately after injection, and dye distribution was noted. The success rate of identification of GPF, number of attempts, and number of successful injections were recorded. The technique was evaluated clinically in 7 patients undergoing dental procedures. Five patients had US-guided injections, and 2 patients received US-assisted greater palatine canal blocks. RESULTS: GPF was successfully identified in 16 hemisectioned heads (n = 16). In 7 of 16 hemisectioned cadaveric specimens (n = 7/16), needle pass was seen on the US and traces of India ink were found within the greater palatine canal and pterygopalatine fossa. In the remaining heads (n = 9/16), the dye was observed in the mucosal tissue of the hard palate anterior to the GPF or in the soft palate. Clinical evaluation reconfirmed successful identification of GPF by US in 6 of 7 patients (n = 6/7). US-guided injections were successful in 6 of the 8 attempted blocks (n = 6/8) with median number (range) of attempts being 2 (1-4). US-assisted injections were successful in 2 patients (n = 2/2). CONCLUSIONS: US has the potential to successfully locate and characterize GPF in normal and edentulous maxilla. US-guided GPN blocks can be technically challenging. The clinical applicability of US guidance or assistance for GPN block needs further evaluation in a larger sample of patients.

Determining position of the inferior alveolar nerve via anatomical dissection and micro-computed tomography in preparation for dental implants.

BACKGROUND: The inferior alveolar nerve courses anteriorly within the mandibular canal, providing sensory nerve supply to the mandibular teeth, the buccal mucosa, the gingiva, and the soft tissues of the lower lip and chin. To avoid damage to this nerve and resulting sensory disturbances, its exact location must be known before placement of a dental implant. Imaging modalities currently used to visualize the position of the inferior alveolar nerve may be inaccurate. This study was undertaken to determine the accuracy of micro-computed tomography (micro-CT) for determining the position of this nerve. METHODS: Micro-CT images of 16 cadaveric hemimandibles were acquired at a slice thickness of 154 µm. Each hemimandible was then sectioned at 6 predetermined locations between the ramus and the mental foramen, to yield 5 corticocancellous bone specimens. The superior, inferior, buccal and lingual distances for bone surrounding the mandibular canal were measured by direct digital caliper and compared with corresponding micro-CT measurements obtained by 3-dimensional visualization and modelling software. RESULTS: There was substantial variability in the vertical position of the inferior alveolar nerve, depending on the length of time since tooth loss and the movement of the nerve from the lingual to buccal position as it courses from the posterior to the anterior aspect of the mandible. However, digital caliper and corresponding micro-CT measurements of the thickness of bone surrounding the inferior alveolar nerve were highly consistent, and no significant differences were detected between the two methods of measurement. CLINICAL SIGNIFICANCE: The findings reported here confirm the accuracy of micro-CT in determining the location of the inferior alveolar nerve during planning for placement of dental implants in the human mandible.

Three-dimensional micro CT derived morphology of the condylus mandibulae in older adults: implications for clinical dentistry / Micro tomografía computarizada tridimensional derivada de la morfología del cóndilo de la mandíbula en adultos mayores: implicaciones para la odontología clínica

Temporomandibular disorder (TMD) is a multi-etiologic disability, accompanied by a wide range of symptoms, requiring a variety of therapies, with TMJ reconstruction considered the most severe. TMJ surgery is associated with many morbidities and limitations, especially in the elderly. Previous studies have determined the shape and dimensions of the Condylus mandibulae in children and adults, but a range of measurements in the elderly population has yet to be created. This study aims to establish a range of measurements and the morphology of the Condylus mandibulae in an older population using micro CT. 14 cadaveric Condylus mandibulaes (8 male, 6 female; average age, 83±8.6) were scanned with microCT and measured using Amira 4.1.1 modeling software. The anteroposterior length (LAP), mediolateral width (WML) and height (H) of each Condylus mandibulae was measured from 5 equidistant slices in the coronal, sagittal and axial planes. Additionally, each Condylus mandibulae was measured at its greatest anteroposterior length, mediolateral width and height using digital callipers on the cadaveric specimen. This study is the first to accurately describe the morphology of the Condylus mandibulae in an elderly population. The length and width measurements of digital calliper (10.51 ± 0.87; 18.33 ± 2.35) and corresponding micro-CT (11.46 ± 1.60; 17.62 ± 2.05) both showed high consistency and reliability. Our findings lay the foundation for the creation of an off-the-shelf Condylus mandibulae prosthesis or anatomically shaped Condylus mandibulae scaffold for elderly patients.

El trastorno temporomandibular (TTM) es una discapacidad multi-etiológica, acompañada por una amplia gama de síntomas, que requieren una variedad de terapias, entre las cuales la reconstrucción de la articulación temporomandibular (ATM) es considerada una de las terapias más graves. La cirugía de la ATM se asocia con muchas morbilidades y limitaciones, especialmente en adultos mayores. Estudios previos han determinado la forma y las dimensiones del cóndilo de la mandíbula en niños y adultos, no obstante aún no se han identificado estas mediciones en una población de adultos mayores. Este estudio tiene como objetivo establecer un rango de mediciones y la morfología del cóndilo de la mandíbula en una población de adultos mayores mediante microtomografía computarizada (microCT). Se escanearon, con microCT, 14 mandíbulas cadavéricas (8 hombres, 6 mujeres; edad promedio: 83 ± 8,6 años), y se realizaron mediciones utilizando el software de modelado Amira 4.1.1. De cada cóndilo de la mandíbula se midió: longitud anteroposterior (LAP), ancho mediolateral (AML) y altura (A), a partir de 5 cortes equidistantes en los planos coronal, sagital y axial. Además, también se utilizaron calibradores digitales para realizar estas mismas mediciones. Este estudio es el primero en describir con precisión la morfología del cóndilo de la mandíbula en una población de adultos mayores. Las medidas de longitud y anchura del calibrador digital (10,51 ± 0,87; 18,33 ± 2,35) y el micro-CT correspondiente (11,46 ± 1,60; 17,62 ± 2,05) mostraron una alta consistencia y confiabilidad. Nuestros hallazgos sientan las bases para la creación de una prótesis de cóndilo de la mandíbula o un andamio condilar de forma anatómica para pacientes de edad avanzada.