Hiro-o Yamaguchi

A study on bone induction in hydroxyapatite combined with bone morphogenetic protein

Our present study consisted of an implantation of artificially made hydroxyapatite (HAP) ceramic pellets under the periosteum of the rabbit skull with subsequent inspection of further progress of bone formation and also of an evaluation of the effects of bone morphogenetic protein (BMP). The results revealed that the alkali phosphatase (AL-P) activity of the pellets was elevated only in those of the bone morphogenetic protein group. The results of determination of bone mineral density at the site of the pellets revealed that the increase in bone mineral density was the most remarkable in the bone morphogenetic protein group rather than the control group. The results of the histopathologic examinations revealed that marginal bone formation was found in the pores on the surface between the pellets and the skull in the control group and in the collagen group, whereas in the bone morphogenetic protein group very active bone formation was found not only on the interface in contact with the skull but also surrounding the whole pellet. It also was noted in the animals in the bone morphogenetic protein group that the pellets were corrupted from the peripheries and then absorbed into the newly formed bone. From these results, the efficacy of the hydroxyapatite-collagen-bone morphogenetic protein complex was made clear, and applications in clinical practice are expected in the near future.

Histidinoalanine-containing phosphoprotein in bone

SummaryHistidinoalanine is a naturally occurring cross-linking amino acid found in mammalian bone, dentin, cartilage and aorta, and also in the extracellular fluid of bivalve clams. The exact components from which this amino acid derives have not been characterized in the case of bone. In this study, the origin of histidinoalanine in bone was investigated in order to clarify the possible role of the matrix component containing this amino acid in bone mineralization. An extract of bovine bone powder with 0.5 M EDTA/1M NaCl was desalted and separated by calcium-induced precipitation. The supernatant fraction was chromatographed successively on Sepharose CL-6B, hydroxyapatite, DEAE cellulose, and reverse-phase high-performance liquid chromatography columns. The fraction with the highest affinity for hydroxyapatite was found to contain the highest concentration of histidinoalanine. A phosphoprotein with a molecular weight of about 24 K that contained 1.2 mol of histidinoalanine per molecule was isolated. The amino acid composition of this fraction showed a high content of acidic amino acids and serine, at least 42% of which was phosphorylated. These results suggested a possible formation mechanism of histidinoalanine that includes the beta-elimination of phosphoserine, producing a dehydroalanine residue and an addition of histidine on it. It was concluded that this low molecular weight phosphoprotein is one of the major sources of histidinoalanine in bovine bone.

Chin Augmentation With Thin Cortical Bone Concomitant With Advancement Genioplasty

The chin plays a prominent role in establishing, not only esthetics, but also function. An incompetent lip seal and tension of the mentalis muscle in swallowing can be important symptoms. Genioplasty is one of the options for addressing the chin deformity and dysfunction caused by morphologic dcficiencies. 1 Postoperative complications can include resorption of grafted bone and a deep labiomental fold. Lateral wings of the genial segment are apt to be resorbed, occasionally leading to the so-called witchs chin appearance, 2 if combined with a deep labiomental fold. To overcome this problem, various strategies have been reported. 3 We describe a novel method to augment the chin structure with a desirable labiomental fold using thin cortical bone alone. Surgeons generally depend on radiography or computed tomography to evaluate genioplasty. However, we had the opportunity to see firsthand the actual state of bony union in these cases when subsequent anterior subapical alveolar osteotomy was performed several months later. We report 2 cases in which substantial bone augmentation was achieved.

Easily manoeuvrable osteotome for pterygomaxillary disjunction

Fig. 1. Swan’s neck osteotome. The curved handle accommodates the cheek. This unique and chunky shape is sometimes difficult to handle. n Le Fort I osteotomy, secure disjunction of the pterygomaxllary suture is essential to mobilise the maxilla and avoid omplications. For desirable disjunction, the vector of force hould be transmitted from a posterolateral to an anteromeial direction, but this is often difficult even with a curved steotome, because the oral commissure is blocked. Reckess attempts to split the suture under difficult circumstances an produce undesirable fractures of the palatal bone, the axillary tuberosity, and the pterygoid plate, occasionally ccompanied by severe haemorrhage.1 To overcome these problems, a specially-designed swan’s eck osteotome is commercially available (Fig. 1).2 This has unique loop that resembles a swan’s neck to accommoate the cheek. Under clinical conditions, however, this is not lways easy to handle because the range of possible angular djustments is narrow (particularly in cases of deep pteryomaxillary sutures) and the force transmitted to the cutting dge will decrease at the loop, which acts as a buffer. The ncision into the mucous membrane also has to be continued ore distally and the periosteum raised widely to insert this hunky instrument, or the periosteum will be torn and the uccal fat-pad will be exposed. We have developed a simle osteotome to enable easy access to the pterygomaxillary uture and allow direct transmission of the force without any eduction (Figs. 2 and 3). The top blade is parallel to the grip to transmit the force in he same direction, with a slight curve to the cutting edge to

Evaluation of a three-stage method for improving mandibular retrognathia with labially inclined incisors using genioplasty, segmental osteotomy, and two-jaw surgery.

We have sometimes encountered difficulty in improving labially inclined teeth, particularly in patients with mandibular retrognathia, because the symphysis menti is often thin and insufficient space is available to permit sagittal rotation of the teeth without root exposure from the alveolar bone. We have previously described a three-stage method to overcome this problem, involving genioplasty for improving the retruded chin, and to construct the infrastructure for subsequent subapical segmental alveolar osteotomy, subapical segmental alveolar osteotomy itself, and, finally, two-jaw surgery. Bone augmentation with thin cortical bone at the gap created on the upper surface of the advanced genial segment was also addressed in the previous report. In the present study, to confirm the benefits of the three-stage method using objective data, cephalometric evaluation was performed in each step. In all cases, pogonion (Pog) was moved forward substantially. Net linear forward movement of Pog and net changes in SN-Pog were from 12 mm to 20 mm and from 4.8° to 7.0°, respectively. Angle of mandibular incisors and interincisal angle also improved to desirable levels. Although this method requires three separate surgeries, the approach safely improves the clinical situation and accentuates treatment efficacy.

Postoperative management of arthroplasty by using unique splints in almost edentulous patient.

e G t d d splint with male keys (Fig. 3) and a maxillary one with female keys that coupled to the male keys were made (Fig. 4) to establish and keep the ideal occlusion postoperatively. anagement of ankylosis of the temporomandibular joint TMJ) is difficult. Arthroplasty without interpositional grafts equires a gap of 10–20 mm to prevent reankylosis, and often esults in deviation of the mouth after shortening of the ramus nd contraction of postoperative scars. Various interposition rafts,1–3 reconstruction,1 and distraction osteogenesis4 have een used, but maintenance of space is the key to a successul arthroplasty. Interposition with a temporalis muscle flap2 nd a Matthews device arthroplasty (MDA)4 has given good esults. The flap prevents ankylosis but does not completely aintain a vertical gap. Though the Matthews device ensures he gap, it requires 2 operations. We think that treatment of nkylosis of the TMJ should ensure an ideal occlusion and equires sequential physiotherapy. Postoperatively it is particlarly important to restore mandibular function and prevent eankylosis. A 68-year-old Japanese man was referred with painless imited mouth opening, which had been getting worse for 2 ears. He had been diagnosed as having rheumatic arthritis on aematological examination, and because he had a buttonhole eformity of a phalanx of the hand. He was almost edentulous, nd preoperative maximum denture-interincisal opening was 2 mm. Computed tomography showed ankylosis between he condyle and glenoid fossa in both TMJ (Fig. 1).

Incidence of anterior disc displacement without reduction of the temporomandibular joint in patients with dentofacial deformity

The aim of this study was to investigate the incidence of anterior disc displacement without reduction (ADDwoR) of the temporomandibular joint (TMJ) in patients with dentofacial deformity. Eighty-eight female patients (176 joints) with skeletal class III malocclusion and 33 female patients (66 joints) with skeletal class II malocclusion, with or without anterior open bite and asymmetry, were evaluated. Magnetic resonance imaging (MRI) of the TMJ was used to diagnose ADDwoR. A statistical analysis was performed to examine the relationship between ADDwoR and skeletal structure. ADDwoR was present in 37 of the 66 joints (56.1%) in class II compared to 34 of the 176 joints (19.3%) in class III (P<0.05). In class III, ADDwoR was significantly more common in joints with mandibular asymmetry (24/74; 32.4%) than in joints with open bite (9/62; 14.5%) and joints with open bite and without mandibular asymmetry (1/38; 2.6%). In class II, ADDwoR was significantly less common in joints with mandibular asymmetry and without open bite (1/8; 12.5%). ADDwoR was only observed on the deviated side in both class III and class II with mandibular asymmetry. The prevalence of ADDwoR differed according to the dentofacial morphology.

Post-operative Stability After Bimaxillary Surgery in Patients with Facial Asymmetry: Comparison of Differences Among Different Original Skeletal Class Patterns.

AbstractPurpose When improving jaw deformity by two-jaw surgery, we are of the opinion from our clinical experience that a certain degree of undercorrection is occasionally beneficial from the perspective of stability. Functional deterioration is not always seen with undercorrection. We conducted this retrospective study to assess post-operative stability in patients with facial asymmetry, with the aim of both clarifying differences between the original three skeletal class patterns, and confirming the efficacy of surgery performed on the basis of our concept. Patients and MethodsAll patients received optimal orthognathic treatment before and after surgery. Surgery was performed by our concept that undercorrection is not always bad. Nineteen patients were enrolled, and separated into three skeletal classes according to the ANB angle, because of the difference of the treatment modalities between them. Evaluations were performed by cephalometric measurements taken at least two-year post-operatively. Transverse occlusal cant, chin deviation, point A, point B, overjet and overbite were assessed.ResultsIn all patients, transverse occlusal cant improved to <4°, which has been reported as the threshold for visual recognition of facial symmetry. Chin deviation was also improved to the degree at which soft tissue can sufficiently mask the asymmetry. The changes remained stable throughout follow-up and satisfaction was obtained from all patients.ConclusionsIrrespective of original skeletal class patterns, post-operative stability of patients with facial asymmetry was achieved. Undercorrection is thus by no means problematic from the clinical perspective of stability and our concept of approach appears valid.

Nodulous sarcoidosis in the cheek muscle : Report of a case

A 59-year-old woman with a subcutaneous nodule in the left cheek showed accumulation of 67Ga in the left cheek, bilateral pulmonary hilar lymph nodes and bilateral lower extremities. An operative specimen from the cheek nodule surrounded by cheek muscle showed non-caseating granuloma consistent with sarcoidosis. Although muscle involvement is quite common, nodulous sarcoidosis in the cheek muscle is rare.A 59-year-old woman with a subcutaneous nodule in the left cheek showed accumulation of 67Ga in the left cheek, bilateral pulmonary hilar lymph nodes and bilateral lower extremities. An operative specimen from the cheek nodule surrounded by cheek muscle showed non-caseating granuloma consistent with sarcoidosis. Although muscle involvement is quite common, nodulous sarcoidosis in the cheek muscle is rare.