煅石膏、骨形成蛋白及羟基磷灰石三元复合人工骨修复骨缺损的实验研究

以煅石膏(PLP）作为颗粒型羟基磷灰石(HA)人工骨粘接成形剂和骨形成蛋白(BMP)的载体，制成三元复合人工骨．分别用HA—bBMP、HA—PLP和单纯HA植入狗下颌骨实验性骨缺损中，采用组织学、定量组织学、免疫组织化学、X线摄片和扫描电镜观察的方法评价该复合人工骨的生物学性能。术后1，2，4，8和16周观察发现，HA—bBMP—PLP复合人工骨具有明显的骨诱导活性．PLP可充当BMP缓慢释放系统载体．增强BMP骨诱导活性，和作为颗粒型HA的粘接成形剂．使复合人工骨具有一定的可塑性和成形性，可达到准确的植入，植入后早期可有效防止HA颗粒移动。本研究证实．HA—bBMP—PLP三元复合人工骨不但可限制植入后HA颗粒的早期移动，更重要的是可以迅速增加新骨形成量．从形态和功能上大大提高了复合人工骨修复骨缺损的质量。     

Progressive dysphagia in an elderly male

Dysphagia can result from a variety of causes, including central nervous and peripheral nervous system, myogenic, and structural disorders. A 76-year-old man underwent anterior cervical disketomy and fusion 10 years ago, with progressive dysphagia noted 2 years ago. Endoscopy showed an oropharyngeal tumor, and lateral plain film evaluation of the neck revealed a cervical plate extrusion. Removal of the instrumentation and tumor with primary closure of the pharyngeal perforation was performed, and dysphagia was resolved postoperatively. We report the case of an unusual presentation in the pharynx. We should not neglect this rare diagnosis, because it can progress to a life-threatening outcome.     

Measuring the residual stress in dental composites using a ring slitting method.

OBJECTIVES: The objective of this experiment was to employ the ring slitting method for the measurement of the residual stress (RS) produced in dental composite materials after polymerization. This study was designed to determine the effect of slitting and measuring time on the residual stress. METHODS: Rings were made in a split brass mold from three composites (Z100/3MESPE; Herculite/Kerr; Heliomolar/Ivoclar) and cured in a Triad II (Dentsply). Two points were scribed, and the rings were slit at either 1 h (Early-group) or 24 h (Delayed-group) after curing the composite. The change in the distance between the scribed points was measured using an image analyzer system at both 1 and 24 h after slitting. From the measured change, circumferential RS was calculated and statistically analyzed with ANOVA/Tukey's (P<0.05). The degree of conversion of each composite at 1 and 24 h was measured with FTIR and analyzed using Student's t-test (P<0.05). RESULTS: In general, the residual stress (range=0.42-2.84 MPa) was highest for Z100 and lowest for Heliomolar, but this depended upon the test conditions. The early cut (1 h slitting), 24 h measurement groups showed the highest residual stress values. SIGNIFICANCE: This study, describes a ring slitting method to measure residual stress generated in dental composites during and after curing. The stress of composite can be affected by the cutting and measurement time.     

Group distal movement of teeth using microscrew implant anchorage

The purpose of this study was to quantify the treatment effects of distalization of the maxillary and mandibular molars using microscrew implants. The success rate and clinical considerations in the use of the microscrew implants were also evaluated. Thirteen patients who had undergone distalization of the posterior teeth using forces applied against microscrew implants were selected. Among them, 11 patients had mandibular microscrew implants and four patients had maxillary implants, including two patients who had both maxillary and mandibular ones at the same time. The maxillary first premolar and first molars showed significant distal movement, with no significant distal movement of the anterior teeth. The mandibular first premolar and first and second molars showed significant distal movement, but no significant movement of the mandibular incisor was observed. The microscrew implant success rate was 90% over a mean application period of 12.3 +/- 5.7 months. The results might support the use of the microscrew implants as an anchorage for group distal movement of the teeth.     

The role of hospital-based dentistry in providing treatment for persons with developmental delay

Hospital dentistry is important to the delivery of oral health care to persons with disabilities. Recent cuts in funding for hospital dentistry in Ontario have placed a great strain on the health care system"s ability to meet the demand for such care. General anesthesia is an accepted treatment option for patients who are uncooperative, but involves inherent risks. In this paper, we present the case of a person with developmental delay who received dental treatment under general anesthesia and subsequently developed complications to support the position that a dental program for persons with special needs should be provided in a hospital setting to minimize their risk of suffering serious complications and to ensure their safety.     

The association of osteoprotegerin gene polymorphisms with periodontitis

Background:  It has been demonstrated that genetic variation accounts for approximately half of the variance in periodontitis. The reported association of polymorphisms in the osteoprotegerin (OPG) gene with osteoporosis suggests that the OPG gene may also influence the genetic risk for periodontitis.
Subjects and methods:  We investigated the distribution of OPG gene polymorphisms in 49 patients with aggressive ( n  =   14) or chronic ( n  =   35) periodontitis and 49 control subjects without periodontitis, using polymerase chain reaction (PCR)–restriction fragment length polymorphism and PCR–single strand conformation polymorphism followed by direct sequencing.
Results:  A total of seven known polymorphisms and one new mutation, G373A, were identified. The T950 and G1181 alleles were more common in patients with periodontitis ( P  =   0.028 and P  =   0.047, respectively) than in control subjects. Especially, G1181 allele was associated with patients with aggressive periodontitis.
Conclusion:  The TG haplotype of T950C and G1181C polymorphisms in the OPG gene may be useful genetic markers for the prediction of periodontitis. Further studies in a larger population are required to determine whether these alleles directly contribute to periodontitis susceptibility.     

Sudden change of a large congenital melanocytic nevus to neurocutaneous melanosis

Neurocutaneous melanosis (NCM) is a congenital phakomatosis in which large congenital melanocytic nevi are associated with a benign or malignant melanocytic tumor of the leptomeninges. Because the prognosis of patients with symptomatic NCM is poor, it is essential to monitor the large congenital melanocytic patient regularly for a neurological evaluation. However, it has not been reported how quickly the lesion could appear. We observed a case of NCM suddenly developing in a large congenital melanocytic nevi patient. With this case, the NCM had developed within six months and was aggravated during the subsequent six months.     

Concurrence of replicative senescence and elevated expression of p16(INK4A) with subculture-induced but not calcium-induced differentiation in normal human oral keratinocytes

Primary normal human oral keratinocytes (NHOKs) undergo differentiation in the presence of calcium concentrations higher than 0.15 mM in vitro, which is useful in investigating the mechanisms involved in the differentiation of epithelial cells. Serial subculture of NHOKs to the postmitotic stage also induces terminal differentiation. However, the detailed mechanisms of both differentiation processes remain substantially unknown. To investigate the molecular differences in these processes, NHOKs were induced to differentiate by exposure to 1.2 mM of calcium and by serial subculture to the postmitotic stage. To study whether the cells were induced to differentiate and to undergo replicative senescence, the amount of cellular involucrin and the expression of senescence-associated beta-galactosidase (SA-beta-gal) were measured respectively. The expression of replicative senescence-associated genes and the activity of telomerase from the differentiated cells were also determined. Both calcium treatment and serial subculture to the postmitotic stage notably elevated the cellular involucrin. The percentage of SA-beta-gal-positive cells was significantly elevated by the continued subculture, but such changes were not observed in keratinocytes exposed to calcium. The concentration of cellular p16(INK4A) protein was progressively increased by the continued subculture but was not changed by calcium treatment. On the other hand, the concentrations of cellular p53 were similar in both differentiation processes. However, telomerase activity was lost in NHOKs that had undergone differentiation by both calcium treatment and serial subculture. The results indicate that calcium-induced differentiation of NHOKs has similar characteristics to their serial subculture-induced differentiation, but that the differentiation processes are not identical, because calcium-induced differentiation does not concur with either replicative senescence or the gradually increased concentration of p16(INK4A).     

Eugenol inhibits K+ currents in trigeminal ganglion neurons

Eugenol, a natural capsaicin congener, is widely used in dentistry. Eugenol inhibits voltage-activated Na(+) and Ca(2+) channels in a transient receptor potential vanilloid 1 (TRPV1)-independent manner. We hypothesized that eugenol also inhibits voltage-gated K(+) currents, and investigated this in rat trigeminal ganglion neurons and in a heterologous system using whole-cell patch clamping. Eugenol inhibited voltage-gated K(+) currents, and the inhibitory effects of eugenol were observed in both capsaicin-sensitive and capsaicin-insensitive neurons. Pre-treatment with capsazepine, a well-known antagonist of TRPV1, failed to block the inhibitory effects of eugenol on K(+) currents, suggesting no involvement of TRPV1. Eugenol inhibited human Kv1.5 currents stably expressed in Ltk(-) cells, where TRPV1 is not endogenously expressed. We conclude that eugenol inhibits voltage-gated K(+) currents in a TRPV1-independent manner. The inhibition of voltage-gated K(+) currents is likely to contribute to the irritable action of eugenol. Abbreviations: human Kv1.5 channel, hKv1.5; transient receptor potential vanilloid 1, TRPV1.