Wednesday, April 3, 2013
Researchers from Tufts University School of Dental Medicine have discovered a statistical association between the injection of local dental anesthesia given to children ages two to six and evidence of missing lower wisdom teeth. The results of this epidemiological study, published in the April issue of The Journal of the American Dental Association, suggest that injecting anesthesia into the gums of young children may interrupt the development of the lower wisdom tooth.
"It is intriguing to think that something as routine as local anesthesia could stop wisdom teeth from developing. This is the first study in humans showing an association between a routinely- administered, minimally-invasive clinical procedure and arrested third molar growth," said corresponding author, Anthony R. Silvestri, D.M.D., clinical professor in the department of prosthodontics and operative dentistry at Tufts University School of Dental Medicine.
Wisdom teeth are potentially vulnerable to injury because their development – unlike all other teeth – does not begin until well after birth. Between two and six years of age, wisdom tooth (third molar) buds begin to develop in the back four corners of the mouth, and typically emerge in the late teens or early adulthood. Not everyone develops wisdom teeth, but for those who do, the teeth often become impacted or problematic.
The American Association of Oral and Maxillofacial Surgeons reports that nine out of 10 people will have at least one impacted wisdom tooth, which can cause bad breath, pain, and/or infection. For this reason, many dentists recommend surgery to remove wisdom teeth to prevent disease or infection.
A developing wisdom tooth, called a bud, is vulnerable to injury for a relatively long time because it is tiny, not covered by bone, and only covered by a thin layer of soft tissue. When a tooth bud first forms, it is no bigger than the diameter of the dental needle itself. The soft tissue surrounding the budding tooth is close to where a needle penetrates when routine dental anesthesia is injected in the lower jaw, for example when treating cavities.
Using the Tufts digital dental record system, the researchers identified records of patients who had received treatment in the Tufts pediatric dental clinic between the ages of two and six and who also had a dental x-ray taken three or more years after initial treatment in the clinic. They eliminated records with confounding factors, such as delayed dental development, and analyzed a total of 439 sites where wisdom teeth could develop in the lower jaw, from 220 patient records.
Group one, the control group (376 sites), contained x-rays of patients who had not received anesthesia on the lower jaw where wisdom teeth could develop. Group two, the comparison group (63 sites), contained x-rays from patients who had received anesthesia.
In the control group, 1.9% of the sites did not have x-ray evidence of wisdom tooth buds. In contrast, 7.9% of the sites in the comparison group – those who had received anesthesia – did not have tooth buds. The comparison group was 4.35 times more likely to have missing wisdom tooth buds than the control group.
"The incidence of missing wisdom teeth was significantly higher in the group that had received dental anesthesia; statistical evidence suggests that this did not happen by chance alone. We hope our findings stimulate research using larger sample sizes and longer periods of observation to confirm our findings and help better understand how wisdom teeth can be stopped from developing," Silvestri continued. "Dentists have been giving local anesthesia to children for nearly 100 years and may have been preventing wisdom teeth from forming without even knowing it. Our findings give hope that a procedure preventing third molar growth can be developed."
Silvestri has previously published preliminary research on third molar tooth development, showing that third molars can be stopped from developing when non- or minimally-invasive techniques are applied to tooth buds.
Tuesday, April 2, 2013
40 percent of bib clips retained aerobic bacteria; 70 percent retained anaerobic bacteria post-disinfection
Researchers at Tufts University School of Dental Medicine and the Forsyth Institute published a study today, "Comprehensive Analysis of Aerobic and Anaerobic Bacteria Found on Dental Bib Clips at Hygiene Clinic", that found that a significant proportion of dental bib clips harbored bacteria from the patient, dental clinician and the environment even after the clips had undergone standard disinfection procedures in a hygiene clinic. Although the majority of the thousands of bacteria found on the bib clips immediately after treatment were adequately eliminated through the disinfection procedure, the researchers found that 40% of the bib clips tested post-disinfection retained one or more aerobic bacteria, which can survive and grow in oxygenated environments. They found that 70% of bib clips tested post-disinfection retained one or more anaerobic bacteria, which do not live or grow in the presence of oxygen.
"The study of bib clips from the hygiene clinic demonstrates that with the current disinfection protocol, specific aerobic and anaerobic bacteria can remain viable on the surfaces of bib clips immediately after disinfection," said Addy Alt-Holland, M.Sc., Ph.D., Assistant Professor at the Department of Endodontics at Tufts University School of Dental Medicine and the lead researcher on the study. "Although actual transmission to patients was not demonstrated, some of the ubiquitous bacteria found may potentially become opportunistic pathogens in appropriate physical conditions, such as in susceptible patients or clinicians."
The study analyzed the clips on 20 dental bib holders after they had been used on patients treated in a dental hygiene clinic. The bib clips were sampled for aerobic and anaerobic bacterial contaminants immediately after treatment (post-treatment clips) and again after the clips were cleaned using disinfecting, alcohol-containing wipes (post-disinfection clips) according to the manufacturer instructions and the clinic's disinfection protocol.
Led by Dr. Bruce Paster, Chair of the Department of Microbiology at the Forsyth Institute, microbiologists at the Forsyth Institute used standard molecular identification techniques and a proprietary, one-of-a-kind technology that can detect 300 of the most prevalent oral bacteria, to analyze the sampled bacteria from the bib clips. The analyses found:
Immediately after treatment and before the clips had been disinfected, oral bacteria often associated with chronic and refractory periodontitis were found on 65% of the clips.
After disinfection, three of the bib clips (15%) still had anaerobic Streptococcus bacteria from the oral cavity and upper respiratory tract. Five percent (5%) of the clips still harbored at least one bacteria from the Staphylococcus, Prevotella and Neisseria species.
Additionally, after disinfection, nine clips (45%) retained at least one anaerobic bacterial isolate from skin.
"The results of our analysis show that there is indeed a risk of cross-contamination from dental bib clips. The previous patient's oral bacteria could potentially still be on the clip and the new patient has a chance of being exposed to infection by using that same bib clip," said Dr. Paster. "It is important to the clinician and the patient that the dental environment be as sterile as possible; thus it's concerning that we found bacteria on the clips after disinfection. This situation can be avoided by thoroughly sterilizing the clips between each patient or by using disposable bib holders."
Researchers involved in the study hypothesized that bacteria found on bib clips after patient care could have been transferred from patients and clinicians to the clips in different ways:
Oral bacteria present in the patient's saliva and the spray or spatter produced during dental treatments may contribute to the presence of bacteria on the disinfected bib clips.
Bacteria can also be transferred from the gloved hands of dental practitioners to the clips prior to- or during the patient's treatment.
Bacteria can be transferred from the patient's hands to the clips if the patient touches the clip.
In a previous study published in August 2012 by researchers at Tufts University School of Dental Medicine and the Forsyth Institute it was found that 20% to 30% of dental bib clips still harbor aerobic bacterial contaminants even after proper disinfection procedures. Rubber-faced metal bib clips were found to retain more bacteria than bib clips made only of metal immediately after treatment and before disinfection. Four other research reports have found bacterial contamination on dental bib holders, including research conducted by U.S. infection control specialist Dr. John Molinari, the University of North Carolina at Chapel Hill's School of Dentistry Oral Microbiology lab and the University of Witten/Herdecke in Germany.