Root Furcation Research Articles

尿試験紙による唾液８成分の同時測定法の構築と残存歯の歯周病の評価

Clinical findings were compared with glucose, protein, albumin, bilirubin, creatinine, pH, occult blood, ketone body, nitrite, and white blood cells contained in whole saliva to investigate the components that most markedly reflect the periodontal condition. The subjects were staff of the Prosthodontics Department, Showa University, and patients who visited for dental treatments (57 subjects in total). At the first time, saliva samples were gargled with 1.5 ml of distilled water for 15 seconds and collected by spitting out into a paper cup. At the second time, saliva samples were collected by the same method. At the third time, saliva samples after chewing paraffin gum for 60 seconds were collected by spitting out into a paper cup. Thus whole saliva collecting that was divided on three times. After sampling, 8 mul of the saliva sample was dripped in reagent sticks for the 10 items of urinary test paper and the reflectance was measured using a specific reflectometer. In the periodontal tissue evaluation, the degree of alveolar bone resorption, probing value, and tooth mobility and the presence or absence of lesions in the root furcation were examined and classified into 4 ranks. The mean values in each periodontal disease rank and correlation between the periodontal disease ranks and the components were statistically analyzed. Bilirubin and ketone body were not measurable. The components density of the 8 items was increased as the periodontal disease rank increased. Regarding the correlation between the periodontal disease ranks and the components, high correlations were noted for protein, albumin, creatinine, pH, and white blood cells. The simultaneous measurement method of 8 salivary components using test paper may be very useful for the diagnosis of periodontal disease of abutment teeth.

下顎枝矢状分割術における骨性治癒形態の経時的観察

The purpose of this study was to clarify the relationship between the cleavage of bone fragments and the stability of osseous healing after performing sagittal split ramus osteotomy (SSRO).The subjects were 11 patients with mandibular prognathism who underwent SSRO on both sides (22 rami). These rami were studied immediately after surgery, 6 months thereafter, and 1 year after surgery by computed tomography. The plane passing through the mandibular foramen was designated as the upper plane, while the plane passing through the root furcation of the first and second molars of the mandible was designated as the lower plane. Examining the cleavage at the anterior and posterior borders of distal and proximal bone fragments, the cleaved planes were classified into three types (smooth, stairway, concave) by a modification of the methods of Nemoto T, et al.(J Jpn Stomatol Soc 50: 227-241, 2001).Many of the concave type anterior borders changed to the stairway type between 6 months to 1 year after surgery, but few changed to the smooth type. Almost all of the stairway and concave type of posterior borders changed to the smooth type between 6 months to 1 year after surgery. Regarding the posterior borders at 1 year after surgery, the cleavage of distal and proximal bone fragments demonstrated stable osseous healing (smooth type) in cases in which the length and width between the bone fragments were large. In order to achieve a stable state of osseous healing at the anterior border, it is therefore important to consider the length between the bone fragments and delete the projection of the distal bone fragment. On the other hand, in order to achieve a stable state of osseous healing of the posterior border, it is important to carefully consider the width between the bone fragments. Sufficient bone contact is necessary for the cleavage of distal and proximal bone fragments in both the anterior and posterior border.The increased distance of the mandibular ramus due to the posterior movement of the SSRO and the clear absorption of the projection of both distal and proximal bone fragments was not observed from 6 months to 1 year after surgery. Therefore, the remodeling in the cleavage between the bone fragments is considered to play a major role in the osseous healing which occurs after SSRO.

Noncanonical Wnt-4 Signaling Enhances Bone Regeneration of Mesenchymal Stem Cells in Craniofacial Defects through Activation of p38 MAPK

Mesenchymal stem cells (MSCs) are multipotent cells that can be differentiated into osteoblasts and provide an excellent cell source for bone regeneration and repair. Recently, the canonical Wnt/beta-catenin signaling pathway has been found to play a critical role in skeletal development and osteogenesis, implying that Wnts can be utilized to improve de novo bone formation mediated by MSCs. However, it is unknown whether noncanonical Wnt signaling regulates osteogenic differentiation. Here, we find that Wnt-4 enhanced in vitro osteogenic differentiation of MSCs isolated from human adult craniofacial tissues and promoted bone formation in vivo. Whereas Wnt-4 did not stabilize beta-catenin, it activated p38 MAPK in a novel noncanonical signaling pathway. The activation of p38 was dependent on Axin and was required for the enhancement of MSC differentiation by Wnt-4. Moreover, using two different models of craniofacial bone injury, we found that MSCs genetically engineered to express Wnt-4 enhanced osteogenesis and improved the repair of craniofacial defects in vivo. Taken together, our results reveal that noncanonical Wnt signaling could also play a role in osteogenic differentiation. Wnt-4 may have a potential use in improving bone regeneration and repair of craniofacial defects.

Comparative evaluation of micro-shear bond strength of adhesive resins to coronal dentin versus dentin at floor of pulp chamber - An Invitro Study

<b>Background and Objectives: </b> To compare the micro shear bond strengths of coronal dentin and pulp chamber dentin using two bonding systems namely Clearfil SE bond and Single bond.<br><b> Methods: </b> Thirty molar teeth were collected for the study out of which sixty samples were prepared. Thirty, 2 mm thick slabs of coronal dentin were prepared from each tooth by removing occlusal enamel perpendicular to the long axis of tooth with low speed diamond disc to expose a flat mid coronal dentin and then thirty pulpal floor dentin samples were prepared by sectioning at mid point between floor of pulp chamber and root furcation. These sixty samples were divided into two major groups depending upon dentin location. GROUP I: 30 samples of coronal dentin. GROUP II: 30 samples of dentin at floor of the pulp chamber. Each group was subdivided into two subgroups depending upon the bonding agent used. Subgroup Ia. IIa: Clearfil SE bond. Sub group Ib, IIb: Single bond).<br><b> Results: </b> Micro shear bond strength showed higher values to coronal dentin compared to dentin at floor of the pulp chamber and Clearfil SE bond showed higher values compared to Single bond in coronal and dentin at floor of the pulp chamber, but statistically insignificant.<br><b> Interpretation and conclusion: </b> Clearfil SE bond showed higher values compared to Single bond in both coronal dentin and dentin at floor of pulp chamber.

The divergent expression of periostin mRNA in the periodontal ligament during experimental tooth movement.

A novel 90-kDa protein named periostin, which is preferentially expressed in the periosteum and the periodontal ligament (PDL), may play a role in bone metabolism and remodeling. However, the precise role of periostin in the PDL remains unclear. Therefore, we examined the expression of periostin mRNA during experimental tooth movement. Experimental tooth movement was achieved in 7-week-old male Sprague-Dawley rats. In control specimens without tooth movement, the expression of periostin mRNA was uniformly observed in the PDL surrounding the mesial and distal roots of the upper molars and was weak in the PDL of the root furcation area. The periostin mRNA-expressing cells were mainly fibroblastic cells in the PDL and osteoblastic cells on the alveolar bone surfaces. The divergent expression of periostin mRNA in the PDL began to be observed at 3 h and continued up to 96 h after tooth movement. The maximum changes, which showed stronger staining in the pressure sites than in the tension sites, were observed at 24 h. The expression of periostin mRNA in the PDL 168 h after tooth movement exhibited a similar distribution to that of the control specimens. These results suggest that periostin is one of the local contributing factors in bone and periodontal tissue remodeling following mechanical stress during experimental tooth movement.

Scanning electron microscopy and energy-dispersive X-ray microanalysis studies of afibrillar cementum and cementicle-like structures in human teeth.

We examined afibrillar cementum (AFC) and cementicle-like structures (CLS) in human teeth by scanning electron microscopy and energy-dispersive X-ray microanalysis. The AFC showed a spur- or island-, plate- and mass-like structure with appositional laminations, while large masses in the enamel fissures enclosed CLS showing concentric appositional rings. Such AFC was observed in enamel fissures, an abnormal enamel pit, dens invaginatus and root furcations with enamel droplets, as well as on the cervical enamel surfaces, where ameloblasts are differentiated at the later or last stage of enamel formation. Cementicle-like structures were occasionally found independent from AFC and some CLS contained epithelial cell-like or ameloblast-like remnants in the core, surrounded by a few or many concentric rings. In addition, cementicles (CEC) in the root furcations also contained the remnants of Malassez's epithelial-rest cells surrounded by a few concentric rings. In some areas, AFC was mixed with enamel structures. These results show that the organic material in some parts of AFC and CLS may be derived from epithelial cells similar to that of CEC. Calcification values of AFC and CLS were significantly higher than that of fibrillar cementum, and the minute crystals are probably apatite.

Morphological Study on the ‘Seams’ in the Multiroot Formation of Rat Molar Teeth

'Seams' of the root furcation with multiroots in rat molar teeth, termed by Lester and Boyde, were investigated using transmitted light and scanning electron microscopy in the formation process. The seam was formed in the junctional line of Hertwig's epithelial root sheaths. The seam formation will be classified into three types in the initial stage based on the position of the epithelial root sheaths approaching each other: (1) the close junction or the very narrow slit or gap formed between them, (2) the clear gap containing mesenchymal cells and (3) the gap containing one blood vessel. When the roots were formed, the seam was formed as follows: (1) the slight ridge composed of the cellular cementum, (2) the proliferation or the depression in the dentine formation and (3) the accessory or lateral canal of the root. These structures were variously combined with each other into one seam, although the slight ridge was very common.

Periodontal treatment of multirooted teeth. Results after 5 years.

This paper describes: (1) a system for classification and treatment of furcation involvements, and (2) a 5-year post-operative evaluation of 100 patients treated for periodontal breakdown in the bi/tri-function areas. The results of this study demonstrate that it is possible to arrest further destruction within the root furcation area. The successful treatment of the multirooted teeth was probably the consequence of: (1) the quasi total elimination of plaque retention areas from the bi/tri-furcation area, and (2) meticulous oral hygiene by the patients.