Comparison of four methods of assessing root surface debridement

BACKGROUND: While there is great interest in measuring the efficacy of root surface debridement, there is little consensus on how this might be best achieved. The aim of this study was therefore to compare four different methods of assessing root surface debridement in their ability to discriminate between ultrasonically instrumented root surfaces and non-instrumented control surfaces. METHODS: Single-session subgingival root debridement was performed by an experienced operator on 30 teeth prior to their extraction. Following extraction, efficacy of root surface debridement was measured by percentage of remaining calculus, instrument efficiency, modified instrument efficiency, and percentage apical plaque border. In addition, the effect of probing depth landmark (apical plaque border versus connective tissue attachment) on outcomes was assessed. RESULTS: The results indicated that percentage apical plaque border demonstrated highly statistically significant differences between instrumented and control surfaces (P= 0.02). No other assessment method was able to discriminate between instrumented and non-instrumented surfaces, and this may be a function of the low amount of root surface calculus in the experimental sample. In addition, choice of probing depth landmark had a notable effect on the outcomes for instrument efficiency and modified instrument efficiency. Ninety-five percent limits of agreement of interexaminer reproducibility were found to be much higher than intra-examiner measurement for all four methods of assessment. CONCLUSIONS: Percentage apical plaque border appeared to be potentially more useful than other methods for assessing the efficacy of debridement of periodontally involved root surfaces, particularly for measuring instrument penetrability.     

Cloning, characterization and immunolocalization of human ameloblastin

Amelogenesis imperfecta is a broad classification of hereditary enamel defects, exhibiting both genetic and clinical diversity. Most amelogenesis imperfecta cases are autosomal dominant disorders, yet only the local hypoplastic form has been mapped to human chromosome 4q between D4S242 1 and the albumin gene. An enamel protein cDNA, termed ameloblastin (also known as amelin and sheathlin), has been isolated from rat, mouse and pig. Its human homolog has been mapped to chromosome 4q21 between markers D4S409 and D4S400, flanking the local hypoplastic amelogenesis imperfecta critical region. Therefore, ameloblastin is a strong candidate gene for this form of amelogenesis imperfecta. To facilitate genetic studies related to this dental disease, we isolated and characterized a human ameloblastin cDNA. A human third molar cDNA library was screened and two ameloblastin clones identified. Nucleotide sequencing of these cDNAs indicated alternative splicing of the putative open reading frame, use of different polyadenylation signals, and a high degree of similarity to reported rat, mouse and porcine cDNAs. Immunohistochemistry studies on embryonic human teeth using an antibody to recombinant ameloblastin indicated ameloblastin expression by ameloblasts with localization in the enamel matrix associated with the sheath structures.     

Differential diagnosis of calcium pyrophosphate dihydrate deposition of the temporomandibular joint

Calcium pyrophosphate dihydrate (CPPD) deposition disease (pseudogout) of the temporomandibular joint (TMJ) is rare. It is characterized by the presence of crystal deposits that are birefringent under polarized light. Although these crystals are characteristically weakly birefringent, some other crystals such as those of calcium oxalate, synthetic steroids, and ethylenediaminetetraacetic acid are also birefringent. The differential diagnosis should therefore be based on a quantitative analysis of crystals or observation of the crystal structure in calcified sections. We present a case of CPPD deposition disease of the TMJ and report on the value of such an analysis to substantiate the diagnosis.     

Bacteriologic features and antimicrobial susceptibility in isolates from orofacial odontogenic infections

OBJECTIVE: The aim of this study was to obtain information for an effective antimicrobial therapy against orofacial odontogenic infections; such information was obtained from recent bacteriologic features and antimicrobial susceptibility data. STUDY DESIGN: The bacteriology and antimicrobial susceptibility of major pathogens in 163 patients with orofacial odontogenic infections to 7 antibiotics was examined. RESULTS: Mixed infection of strict anaerobes with facultative anaerobes (especially viridans streptococci) was observed most often in dentoalveolar infections, periodontitis, and pericoronitis. Penicillin (penicillin G) was effective against almost all pathogens, although it did not work well against beta-lactamase-positive Prevotella. Cefmetazole was effective against all test pathogens. Erythromycin was ineffective against viridans streptococci and most Fusobacterium. Clindamycin exerted a strong antimicrobial activity on anaerobes. Minocycline was effective against almost all the test pathogens. The antimicrobial activity of levofloxacin against viridans streptococci was not strong. CONCLUSIONS: An antibiotic that carries out antimicrobial activity against both viridans streptococci and oral anaerobes should be suitable for treatment of dentoalveolar infection, periodontitis, and pericoronitis. Penicillin remains effective as an antimicrobial against most major pathogens in orofacial odontogenic infections. Cefmetazole, clindamycin, and minocycline may be effective against most pathogens, including penicillin-unsusceptible bacteria.     

Odontogenic ghost cell carcinoma: a case report with reference to the relation between apoptosis and ghost cells

The neoplastic variant of calcifying odontogenic cyst has various designations, and its malignant counterpart has been reported as aggressive epithelial odontogenic ghost cell tumor or odontogenic ghost cell carcinoma. We present a case of odontogenic ghost cell carcinoma with reference to the relation between the ghost cells and apoptosis. A 33-year-old man complained of a mandibular mass. The mass occupied the entire right side of the mandible with destruction of both buccal and lingual bone. The mass also infiltrated into submandibular and sublingual spaces. Histologically, the mass was composed of a solid proliferation of hyperchromatic and pleomorphic epithelial cells with abnormal mitoses. Islands of ghost cells were frequently admixed with nucleated cells, and there were foci of ameloblastic differentiation. Immunohistochemical stains for cytokeratins, involucrin, and apoptosis-related proteins such as Bcl-2, Bcl-X(L), and Bax were done. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) assay was also performed. The nucleated cells adjacent to the ghost cells expressed cytokeratins and involucrin, but the ghost cells had no reaction. Bcl-2 was negative. Both Bcl-X(L) and Bax were demonstrated in the nucleated cells adjacent to the ghost cells. The ghost cells exhibited Bax protein. Some nucleated cells adjacent to the ghost cells were positive with TUNEL assay. The above results indicate that ghost cells undergo abnormal terminal differentiation as an apoptotic process.     

Cytological and cytogenetic effects of the fluoroquinolone ofloxacin on human periodontal ligament fibroblasts

The fluoroquinolone ofloxacin (OFLX) is one of the candidates of antibacterial agents to be topically used against periodontitis. To estimate the maximum concentration of OFLX which exerts little or no adverse effect on the periodontal ligament, cytological and cytogenetic effects of OFLX on human periodontal ligament fibroblasts (Pel cells) were examined. Treatment of Pel cells with < or =0.3 mM OFLX for 24 or 48 h had little inhibitory effect on cellular growth and survival. DNA, RNA and protein syntheses in Pel cells did not decrease in response to treatment with < or =0.3 mM OFLX. The constitutive level of alkaline phosphatase mRNA was retained in cells treated with < or = 0.03 mM OFLX for 24 or 48 h. The level of type I procollagen mRNA was not affected by treatment with < or = 0.003 mM OFLX for 24 or 48 h. Cytogenetic effects of OFLX were evaluated by the ability of OFLX to induce chromosome aberrations in Pel cells. Treatment with OFLX at 0.3-3.0 mM for 6, 24, or 48 h failed to induce chromosome aberrations in Pel cells. The failure of OFLX to induce chromosome aberrations was seen even in the presence of exogenous metabolic activation using a 5% rat liver post-mitochondrial supernatant mixture. These results indicate that treatment of Pel cells with < or =0.003 mM OFLX has few or no adverse effects on the cytological and cytogenetic endpoints examined, suggesting that there would be little adverse effect on growth and differentiation of the periodontal ligament, as well as little cytogenetic activity, if OFLX were to be topically administered to the gingival crevice at the minimal inhibitory concentration (MIC90) against periodontopathic bacteria (< or = 0.0027 mM). It is important to note, however, that extrapolation of these findings to in vivo conditions has yet to be undertaken.     

Influence of firing times and temperature on color stability of low-fusing porcelains for high-functional gold alloys

The purpose of this study was to investigate the effect of firing conditions on color stability. Three commercially available porcelains for high functional gold alloys, Carrara (CA), Deguceram Gold (DE) and Duceragold (DU) were used. In this study color stability was investigated under fire treatment of 1st, 3rd, 5th times and firing temperatures of 0, 20, and 40 degrees C higher than the manufactures standard temperature (CA: 845 degrees C, DE: 780 degrees C, DU: 780 degrees C). L* was degreased in CA 5 times, DE 3 times, DU by repeated firing. No difference was observed among L* of firing temperatures DE and DU, but L* was degreased in CA with firing temperatures of 40 degrees C higher. a* was degreased in CA, DU, DE with repeated firing, a* was degreased 5 times at firing temperatures of higher. b* was degreased in DU, but b* was increased in CA and DE with 5 firings. b* was increased with 5 findings at firing temperatures of 40 degrees C higher.     

Application of CT imaging for dental implant simulation

Accurate diagnosis and exact treatment planning are very important for successful implant treatment. Pretreatment examination and simulations using CT can be especially effective information sources, and diagnosis by CT imaging before treatment substantially enhances the security and safety of the treatment plan. New interactive CT software (SIM/Plant) which enables diagnosis of bone morphology and quality, and also implant simulation on a personal computer through multiplanar reformation of CT images, has been developed. Stereolithography models (SLMs) are reproduced anatomical morphological models of an individual patient's bone structure from the information obtained by the CT scan, and is fabricated out of light cure resin. In this article, SLMs and SIM/Plant for simulation of various examinations and diagnosis incorporating CT information are described, and their features are introduced.     

Changes in facial skin temperature associated with chewing efforts in man: a thermographic evaluation.

Eleven healthy male adults chewed hard and soft chewing-gums for 5 min. A thermographic record of the face on the chewing side was made at the beginning of, during and after the effort. Facial temperature distributions during open/close cyclic unloaded jaw movements were recorded at a later date. The dimensions of the zones whose temperatures were 1.4 degrees C or more higher than the central temperature during the experiment were determined. There was a linear increase in the dimensions of these zones after the chewing. In contrast, the cyclic jaw movements did not result in significant increases. Chewing the hard gum produced significantly higher temperature rises than did the soft in the masseter area. After the chewing effort, the temperature fell gradually, but did not return to the initial state even after 30 min. The overall decreasing pattern of the temperature distribution for chewing the soft gum was similar to that for the hard gum. The facial temperature associated with chewing efforts rose in accordance with the resistance offered by the chewing-gums.     

Histological study of therapy for infected nonvital permanent teeth with incompletely formed apices.

The histological response of periapical tissues to root canal fillings with calcium hydroxide (Ca(OH)2)-iodoform paste, Vitapex (Neo Dental Chemical Products Co., Ltd., Tokyo, Japan), and Ca(OH)2-camphorated paramonochlorophenol (CMCP) paste in nonvital permanent teeth with incompletely formed apices was investigated in 160 root canals from 90 dog premolar and incisor teeth. Periapical inflammatory lesions were initially induced in the experimental teeth. After debridement and cleaning, root canals were filled with one of the two materials. The animals were sacrificed after 30, 60, 120, or 180 days, and histological sections of each specimen were prepared with hematoxylin and eosin staining. Histological findings showed periapical repair and apical closure in both experimental groups. However, the differences in the level of inflammation, apical closure, and reparative process among the two groups were significant (p less than 0.05). It was concluded that the Ca(OH)2-iodoform paste, Vitapex, produced better results than Ca(OH)2-CMCP paste in treatment of infected nonvital permanent teeth with incompletely formed apices.