Fracture resistance of pressable glass-ceramic fixed partial dentures

The aim of the present study was to evaluate the mechanical strength of the Empress2 system, which is based on the use of a high-strength glass--ceramic core of lithium disilicate, and the fracture resistance of fixed partial dentures fabricated with this material. To evaluate mechanical strength, four types of ceramic materials were tested for four-point flexural strength and diametral tensile strength: Empress2 core material, Empress2 layering porcelain, conventional Empress material and Dicor. Then, using Empress2, conventional Empress and Dicor, actual clinical type anterior fixed partial dentures were fabricated for fracture testing. The results showed that the Empress2 core material, at 329 MPa, has more than twice the flexural strength of conventional materials and at 271 MPa, more than four times the diametral tensile strength of conventional materials. Furthermore, fixed partial dentures fabricated with Empress2 had a fracture resistance of 1424 N. That is, they were more than twice as fracture resistant as fixed partial dentures made with conventional materials.     

Fluoride intake in Japanese children aged 3-5 years by the duplicate-diet technique

This study was conducted to determine the fluoride intakes in 94 preschool children aged 3, 4 and 5 (n = 30, 30, 34, respectively) residing in Yokkaichi, Mie Prefecture (< 0.16 ppm F water supply). The parents duplicated all the diets that their children ingested on 3 separate days during a 1-year period. The acid-diffusible fluoride in the diet was isolated by the acid-diffusion technique and measured with a fluoride electrode. The mean daily fluoride intakes from diet alone by children aged 3, 4 and 5 were 0.30 mg (n = 29, SD 0.19), 0.28 mg (n = 30, SD 0.19) and 0.30 mg (n = 34, SD 0.19), respectively. The total estimated mean values from diet and dentifrice were 0.35 mg (n = 29, SD 0.22, range 0.13-1.00), 0.33 mg (n = 30, SD 0.19, range 0.13-0.86) and 0.39 mg (n = 34, SD 0.18, range 0.18-1.01), respectively. It was concluded that the mean (+/-SD) total fluoride from diet and dentifrice in 3- to 5-year-old Japanese children was 0.35 +/- 0.19 mg/day (0.021 +/- 0.012 mg/kg body weight).     

Safety and efficacy of levobupivacaine for postoperative pain relief after the surgical removal of impacted third molars: a comparison with lignocaine and adrenaline

In a randomised, double-blind placebo-controlled single-centre study we compared the efficacy and safety of 0.75% levobupivacaine (without vasoconstrictor) with 2% lignocaine (with adrenaline 1:80,000) and with placebo for postoperative pain relief in 93 patients having day surgery under general anaesthesia for the removal of impacted mandibular third molars. Premedication and preoperative analgesics were not prescribed, although a short-acting opioid analgesic agent was allowed if required during the anaesthetic procedure. Patients were asked to keep a diary card for 2 days after discharge from hospital. The primary endpoint was the number of patients who requested analgesia within 2 h of completion of the operation. In total, 16 (53%) of patients given levobupivacaine requested analgesia compared with 22 (71%) given lignocaine and 23 (72%) given placebo. Patients given levobupivacaine had lower maximum visual analogue pain scores (VAS) and took longer to request rescue medication (P=0.045 compared with lignocaine). Fewer patients after levobupivacaine n=20 (7%) than after lignocaine n=7 (23%) or placebo n=5 (16%) experienced adverse events. Levobupivacaine seems to be a suitable alternative local anaesthetic to lignocaine with adrenaline for pain control after oral operations.     

Gingipains in the culture supernatant of Porphyromonas gingivalis cleave CD4 and CD8 on human T cells

Porphyromonas gingivalis has been shown to attack host defense systems through proteolytic cleavage of a wide variety of members of the systems. In this study, we examined the ability of P. gingivalis culture supernatant to alter the expression of human T cell surface proteins. As judged by flow cytometric analysis, detection of CD4 expression was completely eliminated by the supernatant, but CD8 was less sensitive. When the culture supernatant was added with reducing agents, proteolytic activity was enhanced, resulting in the cleavage of CD8. Mitogenic response of T cells to phytohemagglutinin or concanavalin A was decreased by the treatment of the cells with the culture supernatant of P. gingivalis. The three forms of gingipains (high molecular mass arginine-specific gingipain, arginine-specific gingipain 2 and lysine-specific gingipain) purified from the culture supernatant of P. gingivalis actively cleaved CD4 and CD8 on human T cells, indicating that proteolytic activity of the culture supernatant was due to gingipains. These results suggest that cysteine proteinases like gingipains released from P. gingivalis cleave T cell surface proteins and impede T cell function.     

Tongue brushing and mouth rinsing as basic treatment measures for halitosis

Tongue brushing and mouth rinsing are basic treatment measures for halitosis, and as such are categorised as treatment needs (TN)-1. Although TN-1 is used for treatment of physiologic halitosis treatment, pseudo-, extra oral pathologic or halitophobic patients must also be managed with TN-1 as well as other treatments. Since the origin of physiological halitosis is mainly the dorso-posterior region of the tongue, tongue cleaning is more effective than mouth rinsing. However, practitioners should always instruct their patients on how to brush their tongues to prevent harmful effects. Another approach using a chlorhexidine mouthwash is most effective in reducing oral malodour. However, chlorhexidine should not be used routinely; therefore, zinc-containing mouthwashes have been recommended for use. People can also use chewing gum to reduce oral malodour. Surprisingly, however, it has been noted that sugarless chewing gum increased methyl mercaptan, one of the principal components of oral malodour. Mint did not reduce the concentration of methyl mercaptan either, although these products are widely used for their ability to mask oral malodour. There is a need for the development of a novel food or chewing gum that could considerably reduce VSC levels in mouth air to complement TN-1.     

Risk factors of nerve injury during mandibular sagittal split osteotomy

There is little objective data about whether surgical technique or mandibular anatomy are a risk for inferior alveolar nerve (IAN) injury during bilateral sagittal split osteotomy (BSSO). Orthodromic sensory nerve action potentials (SNAPs) of the IAN were continuously recorded on both sides in 20 patients with mandibular retrognathia during BSSO operation. Changes in latency, amplitude, and sensory nerve conduction velocity (SNCV) at baseline and at different stages of the operation were analyzed. The SNAP latencies prolonged, the amplitudes diminished, and the SNCVs slowed down during BSSO (P = 0.0000 for all parameters). The most obvious changes occurred during surgical procedures on the medial side of the mandibular ramus. There was a clear tendency towards more disturbed IAN conduction with longer duration of these procedures (right side R = -0.529. P = 0.02; left side R = -0.605, P = 0.006). Exposure or manipulation of the IAN usually had no effect on nerve function, but the IAN conduction tended to be more disturbed in cases with nerve laceration. Low corpus height (R = 0.802, P = 0.001) and the location of the mandibular canal near the inferior border of the mandible (R = 0.52, P = 0.02) may increase the risk of IAN injury. There was no correlation between the age of the patients and the electrophysiological grade of nerve damage.     

Survey of congenital anomalies associated with cleft lip and/or palate in 701,181 Japanese people

There have been many reports on congenital anomalies associated with cleft lip and/or palate (CL/CLP) in Japan. However, these reports included data only on patients who came to hospitals; thus the real situation regarding these anomalies remains unclear. Therefore, we surveyed newborns at all delivery facilities in the central area of Japan for the presence of these anomalies, following their progress for 12 consecutive years; at the end of that time, questionnaires were collected and analyzed. In this article, we describe our results.     

A randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part IV: Comparisons of dietary intake

STATEMENT OF PROBLEM: It is unclear whether the replacement of conventional mandibular dentures with implant-supported overdentures alters the diet and thus improves the nutritional intake of edentulous persons. PURPOSE: The purpose of this study was to compare the pretreatment and posttreatment diets of edentulous diabetic patients who received new dentures with either a conventional complete mandibular denture (CD) or a mandibular implant-supported overdenture (IOD). MATERIAL AND METHODS: New dentures were made for 89 edentulous diabetic patients with acceptable metabolic control without insulin (NIT) or with insulin (IT). A randomized approach was used to assign 37 patients a mandibular CD and 52 patients a mandibular IOD supported by 2 cylindrical implants. Of the 89 patients, 58 submitted a dietary log for 7 consecutive days before treatment (PT) and 6 months after treatment completion (PTC). An average daily intake of 28 essential nutrients was determined for each patient at each time interval. Separate 2 x 2 x 2 repeated analysis of variance (ANOVA) tests were performed for each nutrient to compare the means of the 2 denture groups (CD and IOD), 2 diabetic groups (NIT and IT), and 2 time intervals (PT and PTC). The intakes were also compared with the recommended daily allowance (RDA). RESULTS: ANOVAs for all 28 nutritional variables showed no main effect for either denture type or diabetic treatment. Time effects were seen for magnesium, potassium, copper, and monounsaturated fats. The PTC mean intake of the total sample (N = 58) decreased for all 3 minerals and increased for monounsaturated fats with study dentures. Post hoc tests showed the differences between PT and PTC means to be statistically significant for only magnesium (P=.043) and potassium (P=.015). The percentage of patients with PT intake 25% or more below the RDA ranged from 33% to 85% in the CD group and from 24% to 100% in the IOD group for the same 11 nutrients. PTC fiber intake deficiency was noted in almost all participants. Carbohydrate consumption was markedly lower than that recommended by the American Diabetic Association. CONCLUSION: As is often the case with elderly groups, this group of edentulous diabetic patients showed highly comprised nutritional intakes of fiber, vitamins, and minerals. The replacement of old dentures with new dentures that included either a mandibular CD or IOD did not alter patient diets such that the patients improved their nutritional intakes of essential micronutrients and macronutrients.     

Development of a device for the delivery of agents to bone during distraction osteogenesis

Various agents have been theoretically and experimentally implicated as mediators of distraction osteogenesis (DO). The purpose of this study was to develop a vehicle for the potential delivery of these factors to the region of the distraction site in an attempt to manipulate this biologic process. Three adult mongrel dogs (12 months old) had oblique osteotomies performed bilaterally through the gonial regions. In group I, the external distracter was affixed to the right hemimandible of two dogs (n = 2 hemimandibles) with cannulated pins (external diameter = 1.5 mm; lumen diameter = 1.0 mm; length = 60 mm), whereas the distracter on the left was affixed with standard, noncannulated pins of the same dimensions. In group II, cannulated pins were used to affix the external distracter to both hemimandibles (n = 2 hemimandibles) of a dog. The devices were activated after a 5-day latency period and were lengthened at a rate of 1 mm/day for 20 days. During the distraction period, 0.1 ml/d of sterile india ink was injected into the cannulated pins, after which the sterile stylet was replaced. The activation protocol was followed by 28 days of fixation (consolidation period). The hemimandibles from group I underwent removal of soft tissues, acetone fixation, and gross examination/photography, whereas the hemimandibles from group II were prepared for histologic evaluation (whole mount, hematoxylin and eosin staining). All dogs survived to the end of the study and demonstrated successful DO without evidence of complications. Hemimandibles in group I displayed evidence of india ink on both the lingual and buccal cortex around the cannulated pin site, in the regenerate and on the neocortices of the distracted segment. Hemimandibles of group II showed histologic evidence of the india ink being deposited densely around the cannulated pin site and extending in a radial fashion around the pin site into the regenerate. This study demonstrates for the first time a vehicle device for the delivery of an inert dye to the regenerate site during distraction osteogenesis. This vehicle offers the potential of delivery of various factors implicated in distraction osteogenesis (i.e., mitogens) in an attempt to alter this process and also substances (i.e., chemotherapy, antibiotics, etc.) for use in the treatment of various osteopathies.