A study of the time necessary for calcium hydroxide to eliminate microorganisms in infected canals

The objective of this study was to analyze the time necessary for calcium hydroxide to eliminate microorganisms in infected canals. A total of 168 human anterior teeth were prepared and sterilized. One hundred sixty two teeth were inoculated with suspensions of S. aureus, E. faecalis, P. aeruginosa, B. subtilis, C. albicans. Three teeth were used as negative control and three as positive control. Root canals were irrigated with saline and filled with calcium hydroxide paste (CHP). At intervals of 1 minute, and at 7, 15, 21, 27, 30, 45, 60, and 90 days, CHP was removed, samples were collected and immersed in Letheen Broth (LB). Microbial growth was analyzed by two methods, turbidity of the culture medium and subculture on a Brain heart Infusion. After looking for medium change, an inoculum of 0.1 mL obtained from LB was transferred to 7 mL of Brain Heart Infusion (BHI), and subsequently incubated at 37°C for 48 hours. Microbial growth was checked by turbidity of the culture medium and in some cases by Gram stain. All assays were carried out in triplicate under aseptic technique. The results indicated that the antimicrobial effect on the cultures of S. aureus, E. faecalis, P. aeruginosa, B. subtilis, C. albicans and one mixed culture in infected canals by CHP occurred in 60 days.     

In-vitro assessment of a registration protocol for image guided implant dentistry

In this study a computer aided navigation technique for accurate positioning of oral implants was assessed. An optical tracking system with specially designed tools for monitoring the position of surgical instruments relative to the patient was used to register 5 partially or completely edentulous jaw models. Besides the accuracy of the tracking system, the precision of localizing a specific position on 3-dimensional preoperative imagery is governed by the registration algorithm which conveys the coordinate system of the preoperative computed tomography (CT) scan to the actual patient position. Two different point-to-point registration algorithms were compared for their suitability for this application. The accuracy was determined separately for the localization error of the position measurement hardware (fiducial localization error-FLE) and the error as reported by the registration algorithm (fiducial registration error-FRE). The overall error of the navigation procedure was determined as the localization error of additional landmarks (steel spheres, 0.5 mm diameter) after registration (target registration error-TRE). Images of the jaw models were obtained using a high resolution CT scan (1.5 mm slice thickness, 1 mm table feed, incremental scanning, 120 kV, 150 mAs, 512 x 512 matrix, FOV 120 mm). The accuracy of the position measurement probes was 0.69 +/- 0.15 mm (FLE). Using 3 implanted fiducial markers, FRE was 0.71 +/- 0.12 mm on average and 1.00 +/- 0.13 mm maximum. TRE was found to be 1.23 +/- 0.28 mm average and 1.87 +/- 0.47 mm maximum. Increasing the number of fiducial markers to a total of 5 did not significantly improve precision. Furthermore it was found that a registration algorithm based on solving an eigenvalue problem is the superior approach for point-to-point matching in terms of mathematical stability. The experimental results indicate that positioning accuracy of oral implants may benefit from computer aided intraoperative navigation. The accuracy achieved compares well to the resolution of the CT scan used. Further development of point-to-point/point-to-surface registration methods and tracking hardware has the potential to improve the precision of the method even further. Our system has potential to reduce the intraoperative risk of causing damage to critical anatomic structures, to minimize the efforts in prosthetic modelling, and to simplify the task of transferring preoperative planning data precisely to the operating room in general.     

Orofacial pain emerging as a dental specialty

The emerging field of orofacial pain was considered by the American Dental Association for full status as a new dental specialty. While the recognition of orofacial pain as a specialty was denied, the American Academy of Orofacial Pain plans to continue its efforts. Many recent advances in the neuroscience of orofacial pain have led to treatments that provide significant relief for patients with chronic orofacial pain disorders. However, access to this care has been limited, leaving many patients to suffer. Dentists are generally supportive of the efforts to develop oral pain treatment into a specialty because the field will provide benefits for both dentists and their patients. A recent survey of 805 individuals who reported having a persistent pain disorder revealed that more than four out of 10 people have yet to find adequate relief, saying their pain is out of control--despite having the pain for more than five years and switching doctors at least once. "This survey suggests that there are millions of people living with severe uncontrolled pain," says Russell Portenoy, MD, president of the American Pain Society. "This is a great tragedy. Although not everyone can be helped, it is likely that most of these patients could benefit if provided with state-of-the-art therapies and improved access to pain specialists when needed." Development of the field of orofacial pain into a dental specialty has been moved primarily by the fact that historically, patients with complex chronic orofacial pain disorders have not been treated well by any discipline of healthcare. Recent studies of chronic orofacial pain patients have found that these patients have a higher number of previous clinicians and have endured many years with pain prior to seeing an orofacial pain dentist (see Figure 1). Complex pain patients and the clinicians who see them are often confused about who they should consult for relief of the pain. Treatment for those patients within the existing structure of dental or medical specialties has been inadequate, with millions of patients left suffering. Insurers are also confused with regard to reimbursement and may make decisions to exclude treatment for orofacial pain disorders under both dental and medical policies. However, dentistry has taken a leading role in healthcare to address the national problem of developing the field of orofacial pain into a dental specialty. A study of dentists and dental specialists has shown that there is a recognized need and broad support for developing this field into a specialty.     

Genetic variation in the recognition of Porphyromonas gingivalis antigens in mice

T-cell cytokine profiles, anti-Porphyromonas gingivalis antibodies and Western blot analysis of antibody responses were examined in BALB/c, CBA/CaH, C57BL6 and DBA/2J mice immunized intraperitoneally with different doses of P. gingivalis outer membrane antigens. Splenic CD4 and CD8 cells were examined for intracytoplasmic interleukin (IL)-4, interferon (IFN)-gamma and IL-10 by FACS analysis and levels of anti-P. gingivalis antibodies in the serum samples determined by enzyme-linked immunosorbent assay. Western blot analysis was performed on the sera from mice immunized with 100 microg of P. gingivalis antigens. The four strains of mice demonstrated varying degrees of T-cell immunity, although the T-cell cytokine profiles exhibited by each strain were not affected by different immunizing doses. While BALB/c and DBA/2J mice exhibited responses that peaked at immunizing doses of 100-200 microg of P. gingivalis antigens, CBA/CaH and C57BL6 demonstrated weak T-cell responsiveness compared with control mice. Like the T-cell responses, serum antibody levels were not dose dependent. DBA/2J exhibited the lowest levels of anti-P. gingivalis antibodies followed by BALB/c with CBA/CaH and C57BL6 mice demonstrating the highest levels. Western blot analysis showed that there were differences in reactivity between the strains to a group of 13 antigens ranging in molecular weight from 15 to 43 kDa. Antibody responses to a number of these bands in BALB/c mice were of low density, whereas CBA/CaH and C57BL6 mice demonstrated high-density bands and DBA/2J mice showed medium to high responses. In conclusion, different immunizing doses of P. gingivalis outer membrane antigens had little effect on the T-cell cytokine responses and serum anti-P. gingivalis antibody levels. Western blot analysis, however, indicated that the four strains of mice exhibited different reactivity to some lower-molecular-weight antigens. Future studies are required to determine the significance of these differences, which may affect the outcome of P. gingivalis infection.     

Periodontal infection and preterm birth: results of a prospective study

BACKGROUND: Previous studies have suggested that chronic periodontal infection may be associated with preterm births. The authors conducted a prospective study to test for this association. METHODS: A total of 1,313 pregnant women were recruited from the Perinatal Emphasis Research Center at the University of Alabama at Birmingham. Complete periodontal, medical and behavioral assessments were made between 21 and 24 weeks gestation. After delivery, medical records were consulted to determine each infant's gestational age at birth. From these data, the authors calculated relationships between periodontal disease and preterm birth, while adjusting for smoking, parity (the state or fact of having born offspring), race and maternal age. Results were expressed as odds ratios and 95 percent confidence intervals, or CIs. RESULTS: Patients with severe or generalized periodontal disease had adjusted odds ratios (95 percent CI) of 4.45 (2.16-9.18) for preterm delivery (that is, before 37 weeks gestational age). The adjusted odds ratio increased with increasing prematurity to 5.28 (2.05-13.60) before 35 weeks' gestational age and to 7.07 (1.70-27.4) before 32 weeks' gestational age. CONCLUSIONS: The authors' data show an association between the presence of periodontitis at 21 to 24 weeks' gestation and subsequent preterm birth. Further studies are needed to determine whether periodontitis is the cause. CLINICAL IMPLICATIONS: While this large prospective study has shown a significant association between preterm birth and periodontitis at 21 to 24 weeks' gestation, neither it nor other studies to date were designed to determine whether treatment of periodontitis will reduce the risk of preterm birth. Pending an answer to this important question, it remains appropriate to advise expectant mothers about the importance of good oral health.     

Predictable maxillary central incisor reconstruction: surgical and prosthetic case report

Replacing a maxillary incisor is a challenge from both a functional and esthetic standpoint. Techniques that strive to return the site to be reconstructed to its optimal state, thereby mimicking the natural dentition, must be employed. This case report serves to outline the steps necessary to reconstruct a commonly encountered maxillary prosthetic challenge. With a combination of surgical and prosthetic steps, an optimal prosthetic result can be achieved. This cooperation between general dentist, surgeon, and laboratory technician will serve to provide predictable and long-lasting return to a near-normal anatomic state, thereby offering our patients the highest level of care for prosthetic replacement.     

Total IgA and Porphyromonas gingivalis-reactive IgA in the saliva of patients with generalised early-onset periodontitis

Generalised early-onset periodontitis (GEOP) is characterized by acute inflammatory bursts, resulting in rapid destruction of the periodontal apparatus in young adults. An impaired host defense seems to play an important role as etiological factor of periodontitis, especially in the development of GEOP. As the gram-negative Porphyromonas gingivalis has been identified as one of the causative anaerobic bacteria, the humoral immune response to this micro-organism is of particular interest in patients with GEOP. To evaluate the local immune status, we measured total and P. gingivalis-reactive salivary IgA in GEOP patients and in age- and gender-matched periodontally normal controls. We found a significantly lower concentration and secretion rate of total salivary IgA in the GEOP group. Although no differences were detected in the concentration or secretion of P. gingivalis-reactive IgA between groups, the specific fraction of P. gingivalis-reactive IgA of the total IgA was significantly higher in the GEOP group. These findings indicate an inhibition of total secretory IgA in GEOP, while the P. gingivalis-reactive humoral immune system in saliva is, however, activated. P. gingivalis seems to selectively activate IgA lymphocyte clones and induces a switch in the fraction of specific IgA.     

The physiological effects of supplemental oxygen versus nitrous oxide/oxygen during conscious sedation of pediatric dental patients

PURPOSE: This study was performed to compare the effects of nitrous oxide/oxygen (N2O/O2) versus oxygen (O2) as adjuncts to an oral narcotic regimen for pediatric conscious sedation. METHODS: Using a randomized double-blind crossover design, 19 children (mean age 41 +/- 8.6 months) were sedated with chloral hydrate (50 mg/kg), meperidine (1.5 mg/kg) and hydroxyzine pamoate (25 mg) for two appointments. Patients were assigned randomly to receive 100% O2 at one visit and 50% N2O/O2 at the other. Physiologic parameters were measured in five-minute intervals, including respiratory rate, pulse rate (PR), oxyhemoglobin saturation (SpO2) and end-tidal carbon dioxide. Data analyses focused on true desaturations and apnea, level of sedation and sedation outcomes. RESULTS: There were no differences in PR, SpO2 and risk of desaturation between the inhalation agents. The level of sedation was deeper and the sedation outcomes were better in the N2O/O2 group. CONCLUSION: N2O/O2 deepened the sedation while improving its success with minimal alteration in physiologic parameters.