Endoscopic periradicular surgery: a prospective clinical study

We did apicectomies of 30 teeth with periradicular lesions in 23 patients, using a 3 mm endoscope. Two patients failed to attend for postoperative assessment and of the remaining 21 patients who had 28 teeth treated the operation was judged after 1 year to be a success in 26 (93%).     

Isolated osteochondroma near the mandibular angle

A benign tumour of osseous and cartilaginous origins, osteochondroma generally develops in osseous tissue and is frequently found near the end of long bones. It is relatively rare in the oral and maxillofacial region but is common in the mandibular condyle and coronoid process in the pediculate form. This is a report on a rare case of osteochondroma in soft tissue near the mandibular angle without pedicle to the bone.     

Genome-wide association scan for childhood caries implicates novel genes

Dental caries is the most common chronic disease in children and a major public health concern due to its increasing incidence, serious health and social co-morbidities, and socio-demographic disparities in disease burden. We performed the first genome-wide association scan for dental caries to identify associated genetic loci and nominate candidate genes affecting tooth decay in 1305 US children ages 3-12 yrs. Affection status was defined as 1 or more primary teeth with evidence of decay based on intra-oral examination. No associations met strict criteria for genome-wide significance (p < 10E-7); however, several loci (ACTN2, MTR, and EDARADD, MPPED2, and LPO) with plausible biological roles in dental caries exhibited suggestive evidence for association. Analyses stratified by home fluoride level yielded additional suggestive loci, including TFIP11 in the low-fluoride group, and EPHA7 and ZMPSTE24 in the sufficient-fluoride group. Suggestive loci were tested but not significantly replicated in an independent sample (N = 1695, ages 2-7 yrs) after adjustment for multiple comparisons. This study reinforces the complexity of dental caries, suggesting that numerous loci, mostly having small effects, are involved in cariogenesis. Verification/replication of suggestive loci may highlight biological mechanisms and/or pathways leading to a fuller understanding of the genetic risks for dental caries.     

Expression and possible immune-regulatory function of ghrelin in oral epithelium

Originally found in stomach mucosa, ghrelin is a peptide appetite hormone that has been implicated as an immuno-modulatory factor. Ghrelin has also been found in salivary glands and saliva; however, its expression patterns and biological properties in the oral cavity remain unclear. Therefore, we investigated the expression patterns of ghrelin in saliva, gingival crevicular fluid (GCF), and gingival tissue, as well as its in vitro effects on IL-8 production by TNF-α or LPS-stimulated oral epithelial cells. In the clinical samples obtained from 12 healthy volunteers, the concentration of ghrelin in GCF remarkably exceeded that detected in saliva. The expression of ghrelin mRNAs and growth hormone secretagogue (GHS) receptors could be detected in human oral epithelial cells. Immunohistochemical analysis revealed the expression of ghrelin in gingival epithelium, as well as in fibroblasts in the lamina propria. Ghrelin increased intracellular calcium mobilization and cAMP levels in oral epithelial cells, suggesting that ghrelin acts on epithelial cells to induce cell signaling. Furthermore, synthetic ghrelin inhibited the production of IL-8 from TNF-α or LPS-stimulated oral epithelial cells. These results indicate that ghrelin produced in the oral cavity appears to play a regulatory role in innate immune responses to inflammatory infection.     

Physical and mechanical characterization and the influence of cyclic loading on the behaviour of nickel-titanium wires employed in the manufacture of rotary endodontic instruments

AIM: To analyse the influence of cyclic loading on the mechanical behaviour of nickel-titanium (NiTi) wires employed in the manufacture of ProFile rotary endodontic instruments. METHODOLOGY: Nickel-titanium wires, 1.2 mm in diameter, taken from the production line of ProFile rotary endodontic instruments before the final machining step, were tensile-tested to rupture in the as-received condition and after 100 load-unload cycles in the superelastic plateau (4% elongation). The wires were characterized by X-ray energy-dispersive spectroscopy, X-ray diffraction and by differential scanning calorimetry and compared with new size 30, .06 taper ProFile instruments. The fracture surfaces of the wires were observed by scanning electron microscopy. RESULTS: The mechanical properties of the as-received wires, their chemical composition, the phases present and their transformation temperatures were consistent with their final application. Only small changes, which decreased after the first few cycles, took place in the mechanical properties of the cycled wires. The stress at maximum load and the plastic strain at breakage remained the same, while the critical stress for inducing the superelastic behaviour, which is related to the restoring force of the endodontic instruments, decreased by approximately 27%. CONCLUSIONS: The mechanical behaviour of the NiTi wires was modified slightly by cyclic tensile loading in the superelastic plateau. As the changes tended towards stabilization, the clinical use of rotary NiTi ProFile instruments does not compromise their superelastic properties until they fracture by fatigue or torsional overload, or are otherwise discarded.     

Antibacterial activity of two adhesive systems using various microbiological methods

PURPOSE: To compare the antibacterial activities of two dentin bonding systems (DBS), Clearfil Protect Bond and Xeno III, by agar well, paper and dentin disks, and a cavity tooth model. MATERIALS AND METHODS: For the well technique, the test materials were filled in the agar wells inoculated with Streptococcus mutans (ATCC 25175). The paper disks were embedded in adhesives and placed on the seeded agar plates for the second technique. The adhesives were applied on the dentin disks and placed in holes in the plates for the third technique. After 48 h, the zones of inhibition were measured. In the cavity tooth model test, 3 cavities were prepared in the flat occlusal dentin of extracted human molars. The teeth were left in S. mutans for 72 h to allow bacterial invasion. The DBS were applied in the same manner as in clinical application on each of the two infected cavities and the third was left unapplied for control. The teeth were kept in saline for 72 h. Standard amounts of dentin chips were obtained from the cavity walls and the number of bacteria recovered was counted. RESULTS: The results were analyzed by factorial ANOVA and Dunnett C test. Clearfil Protect Bond primer exhibited the greatest inhibition zones followed by Consepsis and unpolymerized Xeno III in all the techniques tested (p < or = 0.05). Clearfil Protect Bond resulted in significantly less bacterial recovery than Xeno III by the tooth cavity method (p < or = 0.05). CONCLUSION: Clearfil Protect Bond was found to be the most antibacterial material with all the techniques used. Furthermore, Clearfil Protect Bond was able to inactivate the bacteria in the cavity more effectively than Xeno III.     

Abrasion of human enamel and dentine caused by toothpastes of differing abrasivity determined using an in situ wear model

Objectives : To determine the rates of enamel and dentine wear in situ during tooth brushing with a range of five toothpastes of differing RDA and REA values. Methods : Enamel/dentine inserts were placed in the buccal aspects of full upper dentures of human volunteers. Enamel wear was determined by change in Knoop indent length and dentine wear was determined from the enamel‐dentine step height, measured using optical profilometry. Results : Significant differences between the test products were found for both enamel and dentine (p < 0.05). However for the conventional toothpastes the rate of wear was similar and differences between the products were not generally statistically significant for either enamel or dentine, despite the fact that their RDA values differed by more than a factor of two. The rate of wear was found to decrease throughout the duration of the study. Conclusions : The study demonstrated that the methodology used is capable of assessing enamel and dentine wear in situ within a relatively short period of time. The data suggest that whilst in vitro tests have value in understanding differences in abrasivity between products, they cannot be used to predict in vivo effects.     

The effect of sectioning the trigeminal sensory root on the periodontally-induced jaw-opening reflex

The experiment was designed to determine the pathway taken to the brain stem by periodontal afferents responsible for the digastric jaw-opening reflex induced by tooth-tapping. Cutting the trigeminal sensory roots of anesthetized decerebrate cats eliminated the ipsilateral periodontally-induced reflex, although the stretch reflexes of the jaw-closing muscles were undiminished. These results suggest that periodontal afferents causing the jaw-opening reflex reach the brainstem through the Vth sensory root, and confirm that muscle spindle afferents travel through the Vth motor root.     

The use of infrared thermography in the evaluation of oral lesions

This study was conducted to quantitate the degree of inflammation associated with oral lesions by using infrared thermography. It was reasoned that the increased vascularity associated with inflamed tissue may result in measurable increases in surface temperature. One subject with normal oral mucosa and three subjects with oral lesions of varying causes were studied with a thermal video system, using an infrared imager and microprocessor. A clinical photograph of each subject was obtained. Multiple thermograms were made in a temperature range of 30.0 C to 34.2 C at a sensitivity of 0.2 C. Photographs were taken on different occasions to determine whether the temperature readings could be duplicated and to test the accuracy of each reading. The normal surface temperature of the control subject's mucosa was significantly cooler than were the temperatures of the inflamed areas in the subjects with lesions induced by chemotherapy. The temperature of the areas of stomatitis was consistent (subject 3, mean = 33.7 C; subject 4, mean = 33.9 C). The necrotic center of a traumatic ulcer inhibited measurement of an underlying inflamed base and, thus, was equivalent to the control in temperature (subject 1 (control), mean = 31.9 C; subject 2 (necrotic lesion), mean = 31.7 C). These results suggest that infrared thermography may provide a means to quantitatively assess the degree of mucosal inflammation.     

Radiographic detection of porosities in removable partial denture castings

The purpose of this study was to discern the existence of structural defects in removable partial denture frameworks by means of radiographs. A simple technique was described using a dental radiograph unit and routine periapical dental films. All components of removable partial denture castings were radiographed with different angulations. The visibility of defects was clear. Structural defects were located and classified in two brands of removable partial denture base metal alloys (Ticonium and Nobilium) commonly used in fabrication of removable partial denture castings. The technique described is simple, inexpensive, not time-consuming, and can be implemented with minimum instrumentation. Future studies with this radiographic method for investigation of internal defects in fixed prostheses or dental implants are recommended.