Evaluating the fracture toughness and flexural strength of pressable dental ceramics: an in vitro study.

The study was undertaken to evaluate the biaxial flexural strength, biaxial flexural strength after etching with 9 % HF acid and fracture toughness of three commonly used pressable all ceramic core materials. Ninety glass ceramic specimens were fabricated from three commercially available leucite based core ceramic material (1) Esthetic Empress, (2) Cergo, and (3) Performance Plus. Thirty discs of each material were divided into three groups of 10 discs each. Biaxial flexural strength (30 discs,) Biaxial flexural strength for samples treated with 9 % HF acid (30 discs) and fracture toughness (30 discs) were evaluated. Core material Performance Plus had the lowest biaxial strength of 124.89 MPa, Cergo had strength of 152.22 MPa and the highest value of 163.95 was reported for Esthetic Empress. For samples treated 9 % HF, Performance Plus had the lowest biaxial strength of 98.37 MPa, Cergo had strength of 117.42 MPa and the highest value of 143.74 was reported for Esthetic Empress. Core material Performance Plus had the lowest fracture toughness of 1.063 MPa, Cergo had strength of 1.112 MPa and the highest value of 1.225 was reported for Esthetic Empress. The results shows that Esthetic Empress had better mechanical properties compared to Cergo had Performance Plus in relation to the parameters tested.

Infra-red spectroscopic analyses of banana waste degraded by oyster mushroom.

Carbon, hydrogen and nitrogen analyses of banana leaf and pseudostem biomass revealed their potentiality as substrates for microorganisms. Infra-red (IR) spectra of both biomass show presence of cellulose, xylan and lignin. IR spectra of leaf and pseudostem biomass degraded in solid state fermentation (SSF) by two Pleurotus species (P. sajor-caju and P. ostreatus) for 40 days showed the utilization of cellulose, xylan and lignin by these microbes. Dynamics of various lignocellulolytic enzymes of Pleurotus species and analyses of carbon, hydrogen and nitrogen contents of degraded biomass supported the same. Both the Pleurotus species exhibited lignin consumption ability on both the substrates.

Large complex odontoma of mandible in a young boy: a rare and unusual case report.

Odontomas are the most common odontogenic tumors. They are broadly classified in to Compound Odontoma and Complex Odontoma. Among them complex odontoma is a rare tumor. Occasionally this tumor becomes large, causing expansion of bone followed by facial asymmetry. Otherwise these tumors are asymptomatic and are generally diagnosed on radiographic examination. We report a rare case of complex odontoma of mandible in a young boy. The tumor was treated by surgical excision under general anesthesia.

Fabrication of a hollow bulb prosthesis for the rehabilitation of an acquired total maxillectomy defect.

The prosthodontic rehabilitation of maxillary defects is a challenging and demanding task which requires careful pre-surgical and post-surgical planning. Maxillary defects can be congenital or acquired. Acquired defects include those following trauma or surgical treatment of benign or malignant neoplasms. A prosthodontist encounters problems such as absence of support, poor retention, and lack of prosthesis stability in treating these patients. The present case report describes a procedure to fabricate a definitive hollow bulb obturator prosthesis for the rehabilitation of a total maxillectomy defect.

Nonsyndromic bilateral multiple impacted supernumerary mandibular third molars: a rare and unusual case report.

A supernumerary tooth is that which is present additionally to the normal series and can be found in any region of the dental arch. An impacted tooth is defined as the one which is embedded in the alveolus, so that its eruption is prevented, or the tooth is locked in position by bone or the adjacent teeth. The occurrence of multiple supernumerary teeth in only one patient in the absence of an associated systemic condition or syndrome is considered as a rare phenomenon. The occurrence of supernumerary teeth in the lower molar region is rare. A prevalence of less than 2% of cases occurring in this region has been estimated. Their occurrence presents a clinical problem for orthodontists and oral surgeons. The cause, frequency, complications, and surgical operation of impacted teeth are always interesting subjects for study and research. An impacted tooth can result in caries, pulp disease, periapical and periodontal disease, temporomandibular joint disorder, infection of the fascial space, root resorption of the adjacent tooth, and even oral and maxillofacial tumours. The management of impacted wisdom teeth has changed over the past 20 years from removal of nonsymptomatic third molars to simple observation. The aim of this paper is to present a rare case of bilateral multiple impacted supernumerary mandibular third molars.

Fabrication of customized sectional impression trays in management of patients with limited mouth opening: a simple and unique approach.

Impression making is not only important but is also the most significant step in the fabrication of any fixed or removable prosthesis. Proper impression making may be hindered by certain pathologic conditions. Reduced mouth opening is one of the common mechanical obstructions for proper orientation of the impression tray in the patient's mouth. In patients with trismus induced by submucous fibrosis, the procedure may be even more difficult to carry out because of reduced tissue resiliency and obliteration of vestibular spaces. Use of sectional trays offers one of the alternatives to overcome the problem of restricted mouth opening. Fabrication of customized impression trays according to the patient dentition improves the accuracy of impression making. The present case reports describe the fabrication of sectional custom trays designed for dentulous patients with chronic tobacco-induced submucous fibrosis.

Laser gingival retraction: a quantitative assessment.

BACKGROUND: Proper gingival retraction improves the prognosis of crowns and bridges with sub gingival finishlines.Use of lasers assists the operator to achieve proper retraction with good clinical results. AIMS: The present study was intended to assess the amount of lateral gingival retraction achieved quantitatively by using diode lasers. SETTINGS AND DESIGN: Study was carried on 20 patients attended to a dental institution that underwent root canal treatment and indicated for fabrication of crowns. MATERIAL AND METHODS: Gingival retraction was carried out on 20 teeth and elastomeric impressions were obtained. Models retrieved from the impressions were sectioned and the lateral distance between finish line and the marginal gingival was measured using tool makers microscope. Retraction was measured in mid buccal, mesio buccal and disto buccal regions. STATISTICAL ANALYSIS: The values obtained were used to calculate the mean lateral retraction in microns. RESULTS: Mean retraction values of 399.5 µm, 445.5 µm and 422.5µm were obtained in mid buccal, mesio buccal and disto buccal regions respectively. CONCLUSIONS: Gingival Retraction achieved was closer to the thickness of sulcular epithelium and greater than the minimum required retraction of 200um.

Surgical Management of Aggressive Central Giant Cell Granuloma of Maxilla through Le Fort I Access Osteotomy.

Giant cell granuloma (GCG) is an uncommon bony lesion in the head and neck region, most commonly affecting the maxilla and mandible and has a female predilection. The clinical behavior of central GCG ranges from a slowly growing asymptomatic swelling to an aggressive lesion. The clinical, radiological, histological features and management of an aggressive GCG of maxilla in an 18-year-old female patient are described and discussed. It is emphasized that surgery is the traditional and still the most accepted treatment for GCG. Le Fort I osteotomy has been advocated as one of the access osteotomy for the surgical management of aggressive and extensive GCG involving the maxilla. The postoperative morbidity and recurrence have been discussed.

A two-component tetrachlorohydroquinone reductive dehalogenase system from the lignin-degrading basidiomycete Phanerochaete chrysosporium.

Tetrachloro-1,4-hydroquinone (TClHQ) is an intermediate in the degradation of pentachlorophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium. Two enzymes required for the reductive dehalogenation of TClHQ to trichlorohydroquinone (TrClHQ) were identified in cell-free extracts of P. chrysosporium. In the presence of GSH, a membrane-bound enzyme converted TClHQ to the glutathionyl conjugate of TrClHQ (GS-TrClHQ). This membrane-bound glutathione transferase was specific for GSH as a cosubstrate. In the second step of the reductive dehalogenation reaction, a soluble enzyme fraction converted GS-TrClHQ to TrClHQ in the presence of GSH, cysteine, or dithiothreitol. Thus, this second enzyme appears to be a GS-conjugate reductase. These two enzyme fractions, working in tandem, also reductively dehalogenated TrClHQ and 2,6-dichlorohydroquinone, which are intermediates in the degradation of chlorophenols by this organism.