Effect of NAMPT on the proliferation and apoptosis in odontoblast-like MDPC-23 cell.

This study aimed to evaluate the physiological role of NAMPT associated with MDPC-23 odontoblast cell proliferation. Cell viability was measured using the (DAPI) staining, caspase activation analysis and immunoblotting were performed. Visfatin promoted MDPC-23 odontoblast cell growth in a dose-dependent manner. Furthermore, the up-regulation of Visfatin promoted odontogenic differentiation and accelerated mineralization through an increase in representative odontoblastic biomarkers in MDPC-23 cells. However, FK-866 cell growth in a dose-dependent manner induced nuclear condensation and fragmentation. FK-866-treated cells showed H&E staining and increased apoptosis compared to control cells. The expression of anti-apoptotic factors components of the mitochondria-dependent intrinsic apoptotic pathway significantly decreased following FK-866 treatment. The expression of pro-apoptotic increased upon FK-866 treatment. In addition, FK-866 activated caspase-3 and PARP to induce cell death. In addition, after treating FK-866 for 72 h, the 3/7 activity of MDPC-23 cells increased in a concentration-dependent manner, and the IHC results also confirmed that Caspase-3 increased in a concentration-dependent. Therefore, the presence or absence of NAMPT expression in dentin cells was closely related to cell proliferation and formation of extracellular substrates.

25-Hydroxycholesterol induces odontoclastic differentiation through RANK-RANKL upregulation and NF-κB activation in odontoblast-like MDPC-23 cells: An in vitro study.

AIM: The physiological effects and cellular mechanism of 25-hydroxycholesterol (25-HC), which is an oxysterol synthesized from cholesterol by cholesterol-25-hydroxylase (CH25H) expressed under inflammatory conditions, are still largely unknown during odontoclastogenesis. This study aimed to evaluate 25-HC-induced odontoclastogenesis and its cellular mechanisms in odontoblast-like MDPC-23 cells. METHODOLOGY: To investigate 25-HC-induced odontoclastogenesis of MDPC-23 cells and its cellular mechanism, haemotoxylin and eosin staining, tartrate-resistant acid phosphatase (TRAP) staining, dentine resorption assay, zymography, reactive oxygen species (ROS) detection, immunocytochemistry, and nuclear translocation were performed. The experimental values are presented as mean ± standard deviation and were compared using analysis of variance, followed by post hoc multiple comparisons (Tukey's test) using SPSS software version 22 (IBM Corp.). A p-value <.05 was considered statistically significant. RESULTS: Lipopolysaccharide or receptor activator of nuclear factor-κB ligand (RANKL) induced the synthesis of 25-HC via the expression of CH25H in MDPC-23 cells (p < .01). Multinucleated giant cells with morphological characteristics and TRAP activity of the odontoclast were increased by 25-HC in MDPC-23 cells (p < .01). Moreover, 25-HC increased dentine resorption through the expression and activity of matrix metalloproteinases in MDPC-23 cells. It not only increased the expression of odontoclastogenic biomarkers but also translocated cytosolic nuclear factor-κB (NF-κB) to the nucleus in MDPC-23 cells. Additionally, 25-HC not only increased the production of ROS (p < .01), expression of inflammatory mediators (p < .01), pro-inflammatory cytokines, receptor activator of NF-κB (RANK), and RANKL but also suppressed the expression of osteoprotegerin (OPG) in MDPC-23 cells. In contrast, CDDO-Me, a chemical NF-κB inhibitor, decreased TRAP activity (p < .01) and downregulated the expression of the odontoclastogenic biomarkers, including RANK and RANKL, in MDPC-23 cells. CONCLUSION: 25-HC induced odontoclastogenesis by modulating the RANK-RANKL-OPG axis via NF-κB activation in MDPC-23 cells. Therefore, these findings provide that 25-HC derived from cholesterol metabolism may be involved in the pathophysiological etiological factors of internal tooth resorption.

Nicotinamide phosphoribosyltransferase regulates the cell differentiation and mineralization in cultured odontoblasts.

The aim of the present study was to investigate the physiological role of nicotinamide phosphoribosyltransferase (NAMPT) associated with odontogenic differentiation during tooth development in mice. Mouse dental papilla cell-23 (MDPC- 23) cells cultured in differentiation media were stimulated with the specific NAMPT inhibitor, FK866, and Visfatin (NAMPT) for up to 10 days. The cells were evaluated after 0, 4, 7, and 10 days. Cell viability was measured using the 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide assay. The mineralization assay was performed by staining MDPC-23 cells with Alizarin Red S solution. After cultivation, MDPC-23 cells were harvested for quantitative PCR or Western blotting. Analysis of variance was performed using StatView 5.0 software (SAS Institute Inc., Cary, NC, USA). Statistical significance was set at p < 0.05. The expression of NAMPT increased during the differentiation of murine odontoblast-like MDPC-23 cells. Furthermore, the up-regulation of NAMPT promoted odontogenic differentiation and accelerated mineralization through an increase in representative odontoblastic biomarkers, such as dentin sialophosphoprotein, dentin matrix protein-1, and alkaline phosphatase in MDPC-23 cells. However, treatment of the cells with the NAMPT inhibitor, FK866, attenuated odontogenic differentiation, as evidenced by the suppression of odontoblastic biomarkers. These data indicate that NAMPT regulated odontoblastic differentiation through the regulation of odontoblastic biomarkers. The increase in NAMPT expression in odontoblasts was closely related to the formation of the extracellular matrix and dentin via the Runx signaling pathway. Therefore, these data suggest that NAMPT is a critical regulator of odontoblast differentiation during tooth development.

Radiological evaluation of the bone and soft tissue thicknesses of the palate for using a miniscrew-supported maxillary skeletal expander.

PURPOSE: The purpose of this study was to determine the palatal bone and soft tissue thicknesses using a miniscrew-supported maxillary skeletal expander (MSE) in Class III malocclusion. METHODS: The thicknesses of the palatal bone and soft tissue were measured in cone-beam computed tomography images obtained from 58 patients. All 20 points were crossing points between five levels, which were defined at 3 mm intervals relative to the line connecting the central fossae of the first molar (Level 0), and 2 mm and 4 mm lateral to the anteroposterior reference line (AP line). RESULTS: The palatal bone was significantly thicker in males than females in the anterior palate up to Level 0, while there was no significant sex-related difference in the posterior palate. There was a tendency for the thickness to decrease in the posterior direction, except in females at 2 mm lateral to the AP line. The palatal soft tissue was significantly thicker in males than females in all positions. At 2 mm lateral to the AP line, the palatal soft tissue thickness decreased in the posterior direction. A 4 mm lateral to the AP line, it initially decreased in the posterior direction, and then increasing again at Level - 6 (6 mm posterior of Level 0). As the lateral distance from the AP line increased, the palatal bone thickness decreased while the palatal soft tissue thickness increased. CONCLUSIONS: These findings provide quantitative data on the palatal bone and soft tissue thicknesses for the miniscrew-supported MSE in the posterior palate.

Anatomical configuration of the inferior alveolar neurovascular bundle: a histomorphometric analysis.

PURPOSE: The inferior alveolar neurovascular bundle (NVB) is important in implant placement and many other surgeries in dentistry because it is a major supplier of sensation and blood to the mandible via the mandibular canal. The purposes of the present study were to determine the areas and diameters of the NVB, the inferior alveolar nerve (IAN), and the inferior alveolar artery (IAA), and to verify the buccolingual location of the mandibular canal. METHODS: The anatomical configuration of the NVB was examined by histomorphometrically analyzing 20 embalmed dentulous hemimandibles. The areas and maximum horizontal and vertical diameters of the NVB, IAN, and IAA were measured according to tooth region. The distances from the internal border of the mandibular canal to the outer surface of the buccal and lingual cortical plates were also measured. RESULTS: The areas of the vertically oval-shaped NVB and IAN appeared to be constant between the molar and premolar regions, which contain the mental branch, and decreased sharply in the lateral incisor after branching off of the mental branch via the mental canal. The mandibular canal was located close to the lingual cortical plate in the posterior tooth region before passing through the mental canal, immediately after which it was situated quite close to the buccal cortical plate, and then closer to the middle toward the anterior tooth region. CONCLUSIONS: The findings of this study provide useful anatomical information that should help to minimize the risk of injury to the NVB during surgical procedures in the mandibular region.

Downregulation of adenomatous polyposis coli by microRNA-663 promotes odontogenic differentiation through activation of Wnt/beta-catenin signaling.

MicroRNAs (miRNAs) regulate cell differentiation by inhibiting mRNA translation or by inducing its degradation. However, the role of miRNAs in odontogenic differentiation is largely unknown. In this present study, we observed that the expression of miR-663 increased significantly during differentiation of MDPC-23 cells to odontoblasts. Furthermore, up-regulation of miR-663 expression promoted odontogenic differentiation and accelerated mineralization without proliferation in MDPC-23 cells. In addition, target gene prediction for miR-663 revealed that the mRNA of the adenomatous polyposis coli (APC) gene, which is associated with the Wnt/ß-catenin signaling pathway, has a miR-663 binding site in its 3'-untranslated region (3'UTR). Furthermore, APC expressional was suppressed significantly by miR-663, and this down-regulation of APC expression triggered activation of Wnt/ß-catenin signaling through accumulation of ß-catenin in the nucleus. Taken together, these findings suggest that miR-663 promotes differentiation of MDPC-23 cells to odontoblasts by targeting APC-mediated activation of Wnt/ß-catenin signaling. Therefore, miR-663 can be considered a critical regulator of odontoblast differentiation and can be utilized for developing miRNA-based therapeutic agents.

Topographical relationship of the greater palatine artery and the palatal spine. Significance for periodontal surgery.

AIM: The aims of this study were to (1) identify the branching pattern and course of the greater palatine artery (GPA), (2) carry out a morphological analysis of the palatal bony prominence that divides the medial and lateral grooves and (3) characterize the topographical relationships between these two structures. METHODS: Thirty-six hemimaxillae were studied with the aid of a surgical microscope to elucidate the GPA. A further 25 dry skulls were examined to establish the morphology of the palatal spine. RESULTS: The most common GPA branching pattern was type I (41.7%, 15 sides), which gave off the medial and canine branches after the bony prominence. The distances from the CEJ to the lateral branch of the GPA were 9.04 ± 2.93 mm (canine), 11.12 ± 1.89 mm (first premolar), 13.51 ± 2.08 mm (second premolar), 13.76 ± 2.86 mm (first molar) and 13.91 ± 2.20 mm (second molar). The palatal spine was frequently observed as the bony prominence (66.3%, 57 sides), and was located at 6.49 ± 1.76 mm from the greater palatine foramen, with a length of 10.42 ± 2.45 mm. There was no a correlation between the bony prominence shape and the GPA branching pattern. CONCLUSIONS: These results could provide the reference data regarding the topography of the GPA for periodontal surgery.

Histomorphometric analysis of the palatal mucosa associated with periodontal plastic surgery on cadavers.

PURPOSE: The palatal mucosa is a major donor site for connective tissue in the field of periodontal plastic surgery, since it satisfies both the esthetic and functional demands of patients. The purpose of this study was to use histomorphometric analysis to measure the thicknesses of the palatal mucosa and the lamina propria including the epithelium on cadavers. METHODS: Thirty-four hemimaxillae of cadavers were examined (13 male and 4 female, mean age 57.2 years). Each maxilla was processed for histological sectioning and subsequently for histomorphometric analysis. The thicknesses of the palatal mucosa and the lamina propria including the epithelium were measured at three points starting from the alveolar crest, at intervals of 4 mm, with the aid of Adobe Photoshop. RESULTS: The thickness of the palatal mucosa at the alveolar crest and at 4 and 8 mm below the alveolar crest were 2.51 ± 0.83 (mean ± SD), 2.92 ± 0.80, and 3.62 ± 0.99 mm, respectively, and thus increasing from the alveolar crest toward the midpalatal suture. Conversely, the thicknesses of the lamina propria including the epithelium at these same positions were 2.06 ± 0.70, 1.54 ± 0.48, and 1.28 ± 0.46 mm, respectively, thus decreasing toward the midpalatal suture. CONCLUSIONS: The present results indicate that clinicians need to be particularly careful when harvesting palatal mucosa that is destined to be used as autogenous donor material for connective tissue in periodontal plastic surgery.

Malaris muscle, the lateral muscular band of orbicularis oculi muscle.

Little is currently known about the variations in the muscular band around the orbicularis oculi muscle (OOc) region, and so the aim of the current study was to describe in anatomic terms the morphologic patterns of the lateral muscular bands of the OOc. Sixty-one hemifaces from embalmed Korean adult cadavers (34 males, 27 females; age range, 45-85 years; mean age, 62.6 years; 28 bilateral and 5 unilateral) were dissected to reveal the anatomic features of the region around the OOc. The lateral muscular band originating from the superficial temporal fascia lateral to the OOc was observed in 54.1% of cases. It terminated at the zygomatic arch region in 17 cases (type A, 27.9%), at the cheek region in 11 cases (type B, 18%), and at the angle of the mouth in 5 cases (type C, 8.2%). When the linear length from the lateral canthus to the tragion was set as 100, the length from the lateral canthus to the lateral edge of OOc was 34.0 (male, 34.1; female, 33.7), and the length between the lateral edge of OOc and the lateral muscular bands of OOc was 6.4 (male, 6.5; female, 6.2). The results of this study suggest that the lateral muscular bands of the OOc may play a significant role in facial animation and dimple formation. In addition, these data provide an index of suggested regions to be injected in patients with periorbital rhytides.

Histomorphometric analysis of the sinus lateral wall and Schneiderian membrane: A cadaveric study.

OBJECTIVES: Sinus augmentation is frequently used to maintain implant stability when there is severe alveolar bone loss. The aim of this study was to determine the thicknesses and histologic features of the sinus lateral wall and Schneiderian membrane in embalmed cadavers. DESIGN: This study included 35 hemimaxillae from 25 cadavers (19 males and 6 females with a mean age at death of 59 years). Specimens obtained from the first premolar to the second molar were embedded in paraffin, stained with hematoxylin-eosin, and observed under a light microscope. The thicknesses of the lateral wall and Schneiderian membrane were measured according to tooth site and measurement level, and their histologic features were evaluated. RESULTS: The mean thicknesses of the lateral wall were 2.22, 2.17, 2.64, and 2.64 mm at the first premolar, second premolar, first molar, and second molar, respectively, and 2.79, 2.24, and 2.12 mm at 0, 2, and 8 mm from the sinus floor. The mean thickness of the Schneiderian membrane did not differ significantly between at the sinus floor (0.41 mm) and 2 mm above the floor (0.38 mm). The lateral wall consisted of the outer cortical plate, trabecular bone in the center, and the inner cortical plate near the Schneiderian membrane, being the inner cortical plate the more porous. CONCLUSIONS: These histomorphometric results for the sinus lateral wall and Schneiderian membrane are expected to provide relevant information for use in sinus augmentation procedures.

Essential role for NFI-C/CTF transcription-replication factor in tooth root development.

The mammalian tooth forms by a series of reciprocal epithelial-mesenchymal interactions. Although several signaling pathways and transcription factors have been implicated in regulating molar crown development, relatively little is known about the regulation of root development. Four genes encoding nuclear factor I (NFI) transcription-replication proteins are present in the mouse genome: Nfia, Nfib, Nfic, and NFIX: In order to elucidate its physiological role(s), we disrupted the Nfic gene in mice. Heterozygous animals appear normal, whereas Nfic(-/-) mice have unique tooth pathologies: molars lacking roots, thin and brittle mandibular incisors, and weakened abnormal maxillary incisors. Feeding in Nfic(-/-) mice is impaired, resulting in severe runting and premature death of mice reared on standard laboratory chow. However, a soft-dough diet mitigates the feeding impairment and maintains viability. Although Nfic is expressed in many organ systems, including the developing tooth, the tooth root development defects were the prominent phenotype. Indeed, molar crown development is normal, and well-nourished Nfic(-/-) animals are fertile and can live as long as their wild-type littermates. The Nfic mutation is the first mutation described that affects primarily tooth root formation and should greatly aid our understanding of postnatal tooth development.

Nfic gene disruption inhibits differentiation of odontoblasts responsible for root formation and results in formation of short and abnormal roots in mice.

BACKGROUND: Nuclear factor I genes play an important role in the development of the brain, lung, and roots of teeth. We had reported that Nfic-deficient mice form normal crowns, but abnormal roots of molar teeth. However, the mechanism by which the disruption of Nfic gene causes abnormal root formation remains unknown. METHODS: To understand this mechanism, the root formation in Nfic-deficient mice was examined and compared to that of wild-type mice by morphological, immunohistochemical, and in situ hybridization analyses. RESULTS: Nfic-deficient mice formed normal Hertwig's epithelial root sheath (HERS) but severely disrupted odontoblast differentiation, leading to the formation of aberrant odontoblasts in the early stage of root formation. They became dissociated and polygonal in shape, lost their orientation and polarity, and did not express dentin sialophosphoprotein. The abnormal roots contained trapped aberrant odontoblasts, thereby resembling osteodentin in overall morphology. No osteoclasts were associated with abnormal roots. Further, the abnormal roots exhibited a decreased number of cementoblasts and cementum formation on the root surface. CONCLUSIONS: The loss of Nfic did not interfere with the formation of HERS, but it caused disrupted odontoblast differentiation, which resulted in the formation of short and abnormal roots, and decreased cementum. This finding suggests that root dentin is required for normal cementum formation. Therefore, Nfic may be a key regulator of root odontoblast differentiation and root formation.

Anatomic evaluation of the retromolar canal by histologic and radiologic analyses.

OBJECTIVES: The aim of this study was to identify the detailed anatomic morphology of the retromolar canal using histologic sections and cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: Twenty-two sides of the mandible obtained from cadavers and CBCT images of 72 patients (144 sides) were analyzed. All mandibles were prepared using conventional methods of tissue processing, stained with hematoxylin-eosin, and measured to elucidate the composition and dimensions of the retromolar canal with the aid of a light microscope. In addition, the prevalence, course, opening position, and distance of the retromolar canal from the second molar were measured on CBCT images. RESULTS: The retromolar neurovascular bundle in the retromolar canal originated from the inferior alveolar neurovascular bundle, and the mean areas of the neurovascular bundle and each artery and nerve contained within it were 0.59, 0.07, and 0.05mm2, respectively. The mean horizontal and vertical diameters of the neurovascular bundle were 0.82 and 0.90mm, respectively. The retromolar canal was detected more often on CBCT images (43.1%, 31 out of 72 patients). It mainly arose vertically (71.0%) from the mandibular canal and opened in the middle portion (57.9%) of the retromolar triangle at a mean distance of 13.13mm from the second molar. CONCLUSIONS: The retromolar canal is a normal anatomic structure that is relatively common and contains both a relatively large artery and a nerve. Clinicians need to pay closer attention to vascular problems as well as nerve damage when they are performing surgical procedures in the retromolar area.

3-dimensional reconstruction of mandibular canal at the interforaminal region using micro-computed tomography in Korean.

PURPOSE: The purpose of this study was to identify the complex course of the mandibular canal using 3D reconstruction of microCT images and to provide the diagram for clinicians to help them understand at the interforaminal region in Korean. MATERIALS AND METHODS: Twenty-six hemimandibles obtained from cadavers were examined using microCT, and the images were reconstructed. At both the midpoint of mental foramen and the tip of anterior loop, the bucco-lingual position, the height from the mandibular inferior border, the horizontal distance between two points, and position relative to tooth site on the mandibular canal were measured. The angle that the mental canal diverges from the mandibular canal was measured in posteriorsuperior and lateral-superior direction. RESULTS: The buccal distance from the mandibular canal was significantly much shorter than lingual distance at both the mental foramen and the tip of anterior loop. The mandibular canal at the tip of anterior loop was significantly located closer to buccal side and higher than at the mental foramen. And the mental canal most commonly diverged from the mandibular canal below the first premolar by approximately 50° posterior-superior and 41° lateral-superior direction, which had with a mean length of 5.19 mm in front of the mental foramen, and exited to the mental foramen below the second premolar. CONCLUSION: These results suggest that it could form a hazardous tetrahedron space at the interforaminal region, thus, the clinician need to pay attention to the width of a premolar tooth from the mental foramen during dental implant placement.

Morphometric analysis of the mandibular lingual foramina using cone-beam computed tomography in elderly Korean / Análisis morfométrico de los forámenes linguales mandibulares mediante tomografía computarizada de haz cónico en adultos mayores coreanos

SUMMARY: The aim of this study was to determine the morphologic characteristics of the lingual foramen and lateral lingual foramen using cone-beam CT in elderly Korean. Cone-beam CT images were obtained from 80 Korean older than 50 years (mean age, 65.2 years). The prevalence of the lingual and lateral lingual foramina at the lingual aspect of the mandible was determined. The diameter and height to the upper margin of the foramina from the mandibular inferior margin, and the bone height to the alveolar crest from the mandibular inferior margin were measured. In addition, the location of the lateral lingual foramen, the direction of its canal, and the presence of communication with the mandibular canal were evaluated. All of elderly Korean possessed at least one lingual foramen, with two or three foramina occurring in 77.5 % of Korean. A lateral lingual foramen was observed in 91.3 % of Korean, with the prevalence being highest at the second premolar in dentulous cases (21.6 %; 33/153). The very high frequencies of these foramina were attributable to high frequencies of relatively small-diameter inferior lingual foramen and lateral lingual foramen in the incisor region. The prevalence of a large-diameter (≥1 mm) superior lingual foramen was high, at 31.0 %. A large-diameter lateral lingual foramen in the premolar region occurred at a frequency of 17.0 %; communication with the mandibular canal was observed in 70.0 % of these cases. These quantitative data on the lingual and lateral lingual foramina of the mandible provide valuable information that could help to avoid surgical complications during implant placement in elderly Korean.

RESUMEN: El objetivo de este estudio fue determinar las características morfológicas del foramen lingual y del foramen lingual lateral mediante TC de haz cónico en adultos mayores coreanos. Se obtuvieron imágenes de TC de haz cónico de 80 coreanos mayores de 50 años (edad media, 65,2 años). Se determinó la prevalencia de los forámenes linguales y linguales laterales en la cara lingual de la mandíbula. Se midió el diámetro y la altura hasta el margen superior de los forámenes desde el margen inferior mandibular, y la altura ósea hasta la cresta alveolar desde el margen inferior mandibular. Además, se evaluó la ubicación del foramen lingual lateral, la dirección de su canal y la presencia de comunicación con el canal mandibular. Todos los adultos mayores coreanos tenían al menos un foramen lingual, con dos o tres forámenes en el 77,5 %. Se observó un foramen lingual lateral en el 91,3 %, siendo la prevalencia más alta en el segundo premolar en casos dentados (21,6 %; 33/ 153). Las mayores frecuencias de estos forámenes se atribuyeron a altas frecuencias de foramen lingual inferior y foramen lingual lateral de diámetro relativamente pequeño en la región de los incisivos. La prevalencia de un foramen lingual superior de gran diámetro (≥1 mm) fue alta, del 31,0 %. Un foramen lingual lateral de gran diámetro en la región premolar ocurrió con una frecuencia del 17,0 %; se observó comunicación con el canal mandibular en el 70,0 % de estos casos. Estos datos cuantitativos sobre los forámenes linguales y linguales laterales de la mandíbula proporcionan información valiosa que podría ayudar a evitar complicaciones quirúrgicas durante la colocación de implantes en adultos mayores coreanos.

The effects of interproximal distance between roots on the existence of interdental papillae according to the distance from the contact point to the alveolar crest.

BACKGROUND: This study investigated the existence of interdental papillae at certain distances from the contact point to the alveolar crest, depending on the interproximal distance between roots. METHODS: A total of 206 papillae from 80 patients were examined after the inflammation of the papillae had been minimized using non-surgical periodontal therapy. The existence of the interdental papillae was determined using the following categorization: 1) papillae were deemed to be absent if they did not extend all the way up to the contact point between the teeth; and 2) papillae were determined to be present if they filled up to the entire proximal space. The interproximal distance between roots and the distance from the contact point to the alveolar crest were measured when a full-thickness flap was used. The number of papillae present interproximally between roots, according to the distance from the contact point to the alveolar crest, was analyzed using the x2 analysis method, and the linear-by-linear association analysis method was used for trend analysis. RESULTS: The number of papillae that filled the interproximal space decreased with increasing distance from the contact point to the alveolar crest (P <0.05). In addition, the number of papillae that filled the interproximal space decreased with increasing interproximal distance between roots (P <0.05) and became more prominently decreasing with the increasing distance from the contact point to the alveolar crest (especially 4, 5, and 6 mm) (P <0.05). CONCLUSION: The results suggest that the interproximal distance between roots and the distance between the contact point and the alveolar crest have an independent and combined effect on the existence of interproximal papillae.

Comparative fine structure of the epididymal spermatozoa from three Korean shrews with considerations on their phylogenetic relationships.

This study examined the fine structures of epididymal spermatozoa on the lesser white-toothed shrew (Crocidura suaveolens), the Japanese white-toothed shrew (C. dsinezumi) and the big white-toothed shrew (C. lasiura) belonging to the subfamily Crocidurinae living in Korea. In the spermatozoa of C. suaveolens, the head has a large acrosome, a smooth inner acrosomal membrane and a wavy, finger-like, electron-dense apical body. The neck has a solid proximal centriole that is filled with electron-dense material. These results showed the spermatozoa of C. suaveolens possess the characteristics of both Crocidurinae and Soricinae. In C. dsinezumi and C. lasiura, the head has a large acrosome, a serrated inner acrosomal membrane and a common apical body. The neck has a fistulous proximal centriole with slightly dense electron granules. These results showed the typical characteristics of Crocidurinae. Although C. suaveolens belongs to the subfamily Crocidurinae, the spermatozoan morphology is different from C. dsinezumi and C. lasiurai because it has conserved characteristics of the subfamily Soricinae.

Histologic features and fascicular arrangement of the inferior alveolar nerve.

OBJECTIVES: Knowledge of the various possible morphologies and courses of the inferior alveolar nerve and artery is important for successful and safe surgical procedures in the mandibular region. The purpose of this study was to verify the histologic features and fascicular arrangement of the inferior alveolar nerve and artery relative to tooth region. MATERIALS AND METHODS: Twenty embalmed dentulous hemimandibles were examined (eight males and two females; mean age, 58.2 years). The hemimandibles were prepared for routine histology and stained with hematoxylin-eosin and Masson's trichrome. The histologic features, fascicular arrangement, courses, and areas of the inferior alveolar nerve and artery were investigated with the aid of a light microscope. RESULTS: The inferior alveolar neurovascular bundle comprised the inferior alveolar nerve, which appeared as a large trunk comprising two major nerves (the mental and dental nerves), and the inferior alveolar artery, which occupied a relatively small portion of the bundle. The mental nerve was located inferolingually in the third molar region and turned to the buccal side in the first molar region, separating from the dental nerve before reaching the mental foramen. The mandibular incisive canal with a bony wall was not found in the lateral incisor region; instead, small dental nerve fascicles and arteries presented consistently in the intertrabecular spaces. The inferior alveolar artery traveled above the inferior alveolar nerve over the entire mandibular canal. CONCLUSIONS: These results provide data that are relevant to treatment planning for operative procedures such as implant placement, endodontic treatment, and osteotomy in the mandibular region.

Morphological assessment of the anterior loop of the mandibular canal in Koreans.

The mandibular canal divides into the mental and incisive canals at the premolar region, forms the anterior loop which crosses anterior to the mental foramen, and turns back to reach the mental foramen. The aim of this study was to elucidate the general anatomical structure of the anterior loop of the mandibular canal using morphometry. Twenty-six hemimandibles from 19 cadavers (16 males, 3 females; mean age at death, 54.4 years) were studied by meticulous dissection with the aid of a surgical microscope. The location of the anterior loop, the diameters of the mandibular, mental, and incisive canals, and their distances from bony landmarks were measured using digital calipers. The anterior loop of the mandibular canal was located 3.05±1.15 mm (mean±SD) anterior to the anterior margin of the mental foramen and 2.72±1.41 mm inferior to the superior margin of the mental foramen, and was 4.34±1.46 mm long. The diameters of the mandibular, mental, and incisive canals were 2.8±0.49, 2.63±0.64, and 2.22±0.59 mm, respectively. The distances between the inferior border of the mandible and each of these canals were 7.82±1.52, 10.11±1.27, and 9.08±1.66 mm, respectively. The anterior loop of the mandibular canal was located a mean of 3.1 mm anterior and 2.7 mm inferior to the mental foramen, and continued upward and backward into the mental canal, and forward into the incisive canal. These detailed morphological features of the anterior loop of the mandibular canal represent useful practical anatomical knowledge regarding the interforaminal region.

Thickness of the palatal masticatory mucosa with reference to autogenous grafting: a cadaveric and histologic study.

The aims of this study were to measure the thickness of the palatal masticatory mucosa and determine its histologic characteristics with reference to autogenous grafting. Thirty-two fully dentate, cadaver hemimaxillae were examined (from 13 men and 3 women; mean age, 57.1 years). The thickness of the palatal masticatory mucosa was assessed at 24 standard measurement points on the sectioned specimens after decalcification, and then the specimens were processed for embedding in paraffin, sectioned, and stained with hematoxylin and eosin. The thickness of the palatal masticatory mucosa varied by tooth site as follows: 3.55 ± 1.09 mm (mean ± SD; distal canine), 3.51 ± 0.99 mm (distal first premolar), 3.28 ± 1.07 mm (distal second premolar), 2.83 ± 1.00 mm (midline first molar), 2.92 ± 1.03 mm (distal first molar), and 3.15 ± 1.66 mm (distal second molar). The thickness also varied according to distance from the cementoenamel junction (CEJ): 2.35 ± 0.79 mm at 3 mm below the CEJ, 2.65 ± 0.77 mm at 6 mm, 3.52 ± 0.94 mm at 9 mm, and 4.29 ± 1.14 mm at 12 mm. Histologic analysis showed that the thickness of the lamina propria decreased toward the posterior palatal area and midpalatal suture, while that of the submucosa increased. These results suggest that the most appropriate donor site for gingival autogenous grafting is the region 3 to 9 mm below the CEJ between the distal surface of the canine and the midline surface of the first molar.