Instrument handle size and weight affects arm muscles

Dental hygienists rank first among all occupations in the U.S. for suffering from carpal tunnel syndrome (CTS), according to the U.S. Bureau of Labor and Statistics. CTS is a debilitating condition, often leading to a reduced workload or forced retirement from clinical practice.

Researchers at University of California-San Francisco evaluated the effects of instrument handle size and weight on muscle contractions and pinch force of the thumb. Ten instruments of varying handle sizes and weights were tested, each with a Hu-Friedy Gracey 11 curette tip. Twenty-four dentists and hygienists tested the instruments in a lab setting on a typodont. The group was evenly divided between men and women and all were right-handed.

Each clinician participated in a three-hour data collection period, testing all ten instruments on the mesial of the mandibular second premolar. A new plastic tooth painted on the mesial with nail polish was used for each instrument. Electrodes were attached to four muscles of the right forearm and a small pressure pad was attached to the instrument handle, just under the thumb. Subjects were given time to practice with the instruments and were then asked to remove the nail polish with the same force as they would use to remove calculus on a real patient, without damaging the tooth surface. They were allowed two minutes for each instrument, with a five-minute rest between instruments.

The 10 mm diameter handle required less muscle load and pinch force, compared to handles both larger and smaller. The clinicians preferred the lighter-weight 10 mm diameter handles. No differences were observed between instruments for removal of the nail polish. Clinical research is needed to confirm these findings.

Clinical Implications: Instrument handles that are 10 mm in diameter and weigh no more than 15 grams seem to be choice for reducing muscle contraction and thumb pinch force.

Dong, H., Barr, A., Loomer, P., LaRoche, C., Young, E., Rempel, D.: The Effects of Periodontal Instrument Handle Design on Hand Muscle Load and Pinch Force. JADA 137: 1123-1130, 2006. n

Are dental restorations a risk for attachment loss?

Restorations are risk factors for new carious lesions and enhance plaque accumulation due to margin placement, surface integrity and material used. Only a few research studies have evaluated the risk of carious lesions and/or restorations for periodontal attachment loss. These studies present conflicting results.

Researchers at the University of Otago in Dunedin, New Zealand, evaluated participants in a long-term health and development study to determine the influence of carious lesions and restorations on periodontal attachment loss. Study participants were all born at the Queen Mary Hospital in Dunedin between April 1972 and March 1973. This ongoing study has evaluated participants at many points: three, seven, nine, 11, 13, 15, 18, 21, 26 and 26 years of age. The dental researchers entered when the subjects were 32 years old, so dental and periodontal data from age 26 and age 32 were used. The goal was to determine if a restoration on a mesial or distal surface led to more attachment loss than sound interproximal surfaces. Other risk factors were also considered: smoking, poor oral hygiene and general demographics.

Nearly 1,000 subjects participated and more than 40,000 proximal surfaces were evaluated. No difference was observed in the influence of carious lesions versus restored surfaced on attachment loss. Poor oral hygiene and smoking were consistently associated with attachment loss. Daily flossing had a positive influence on attachment loss. The authors conclude that interproximal caries and restorations are a risk factor for periodontal attachment loss, thus emphasizing the value of prevention and monitoring.

Clinical Implications: Here’s another reason to prevent dental caries. The untreated lesions as well as restorations contribute to periodontal disease progression as measured by attachment loss.

Broadbent, J., Williams, K., Thomson, W., Williams, S.: Dental Restorations: A Risk Factor for Periodontal Attachment Loss? J Clin Perio 33: 803-810, 2006.

Is full-mouth disinfection the treatment of choice?

In Perio Reports Vol. 18, #10, a summary of full-mouth disinfection (FMD) was presented. Two months following publication of that article in the Journal of Clinical Periodontology, a letter to the editor was published challenging conclusions drawn by those authors. The letter’s author is one of several researchers to publish conflicting research findings on FMD.

Several important points were presented concerning the presence of subgingival pathogenic bacteria, the value of short-term antibody increases, and the lack of contribution made by chlorhexidine (CHX).

The presence of pathogenic bacteria in subgingival areas of healthy sites does not in and of itself signify disease initiation or progression. A specific species may be present, but not be pathogenic to the host; the individual may be resistant to particular species; and/or the local conditions may not favor pathogen replication and initiation of disease.

Completing FMD in one day seems to have a stronger short-term influence on antibody levels than the traditional quadrant approach with visits one to two weeks apart. However, this short-term shift may have no clinical significance. Changes occur only during active therapy and vary considerably between patients, making them difficult to interpret.

In the 2006 study, the authors claimed superiority of FMD with extensive use of CHX over all treatment done without CHX. This is in direct contrast to the same group’s study in 2000 that questioned the role of CHX, finding comparable healing for FMD treatment with or without CHX. Clinical data in the 2006 study actually showed greater healing in the FMD group without CHX compared to the quadrant group without CHX, however these differences failed to reach statistical significance at eight months.

Similar plaque levels were reported for both groups in the 2006 study in contrast to other studies that showed treatment in a single day resulted in higher plaque levels several months later. It must be pointed out that the 2006 FMD group was seen as many times as the quadrant group to reinforce oral hygiene. This cannot be compared to a true single visit approach.

Clinical Implications: Evidence is lacking to conclude that FMD is now the treatment of choice. Patients and clinicians together should select the treatment approach that best fits their needs and wants.

Apatzidou, D.: One Stage Full-Mouth Disinfection – Treatment of Choice? J Clin Perio 33: 942-943, 2006.

Chlorhexidine controls subgingival bacterial levels

Scaling and root planing (SRP) is the most common periodontal treatment used today. Many studies show the effectiveness of SRP, both with and without the use of adjunctive antimicrobials. Chlorhexidine (CHX) is the most common mouth rinse used in conjunction with SRP for controlling bacterial levels.

Researchers at Guarulhos University in Brazil compared SRP with and without the use of CHX mouth rinse. Statistical calculations determined that 14 subjects would be needed in each treatment group to detect a true change of 1 mm between groups. The university pharmacy provided both the 0.12% CHX rinse and the placebo rinse.

Baseline clinical and microbiological data were collected, oral hygiene instructions given and all subjects received Colgate Total toothpaste for use during the study. Instrumentation was carried out in a maximum of six one-hour visits, using local anesthesia. Test and control patients were instructed to use their assigned rinses twice daily for one minute. Subjects returned weekly to check rinsing and oral hygiene compliance. Clinical and microbiological data were collected at 42 days and 63 days post treatment.

Both test and control groups showed improved periodontal health following treatment. The CHX group showed lower plaque and bleeding upon probing scores compared to the placebo group. Microbial testing confirmed a greater reduction in subgingival bacteria in the CHX group than in the placebo group. These results are similar to studies that provided weekly supragingival polishing for three months after SRP treatment.

Clinical Implications: These findings suggest that rinsing with CHX may provide a benefit similar to weekly supragingival polishings following treatment.

Faveri, M., Gursky, L., Feres, M., Shibli, J., Salvador, S., de Figueiredo, L.: Scaling and Root Planing and Chlorhexidine Mouthrinses in the Treatment of Chronic Periodontitis: A Ramdomized, Placebo-Controlled Clinical Trial. J Clin Perio 33: 819-828, 2006.

Why does calculus form on the lingual of the lower anteriors?

Plaque biofilm mineralizes to form supragingival calculus, forming most often on the lingual of the mandibular anterior teeth, and to a lesser extent, the facial of the maxillary posteriors teeth.

There is a critical pH level between five and six where plaque and saliva are saturated with calcium phosphates, in particular hydroxyapatite. Above this critical pH, calculus forms. Below this pH, acid levels lead to caries.

Exposure to fermentable carbohydrates will lower the pH, due to acid production. The higher the concentration of carbohydrate in the saliva over the plaque, the more will diffuse into the plaque and lead to greater acid formation. Research has shown that carbohydrate concentrations vary throughout the mouth when eating or drinking sugar containing substances. Measuring salivary sucrose levels following a one minute rinse with 10% sucrose, eating a donut, sucking on a candy mint, chewing a sucrose containing gum, or drinking orange juice showed lower sucrose concentrations on the lingual of the mandibular anteriors and the facial of the maxillary posterior molars.

The velocity of saliva over the plaque and plaque thickness determines the rate of acid release from plaque. Plaque is often thin in the lower anterior region, thus giving up acids quickly. When eating sugars, the salivary flow increases, particularly on the lingual of the mandibular anterior teeth and the facial of the maxillary posterior teeth. As the salivary flow increases and takes away the acid, there is an increase in pH, resulting in the formation of supragingival calculus.

Clinical Implications: Understanding the pH changes related to acid release patterns of plaque will help you understand the tendency for more calculus to form on the lingual of lower anterior teeth.

Dawes, C.: Why Does Supragingival Calculus From Preferentially on the Lingual Surface of the 6 Lower Anterior Teeth? J Canadian Dent Assoc 72: 923-926, 2006.

Periodontal care prior to referral

It is reported that 33% of the general population has periodontal disease, with figures vary from 28% to 63%, and 8% to 18% showing signs of advanced disease. A review of 200 studies concluded that mild to moderate periodontitis can be successfully treated with non-surgical therapy.

A study published in 2003 reported more severe disease and more missing teeth in patients referred to a periodontist in 2000 than in 1980, suggesting that general dentists were not providing adequate care. Based on that finding, this study was undertaken to evaluate periodontal care prior to referral.

One hundred patients referred to three periodontal offices in the Kansas City area were included. Conclusions were drawn using the periodontists’ examination data and written questionnaires from the patients. No attempt was made to gather accurate data on previous treatment or attempts at referral by the general dentists. Most patients made their appointment with the periodontist within one year of referral.

The patients were classified as having moderate periodontitits (26%) or severe periodontitis (74%). When asked who performed their “cleanings” it was the dentists for 42% in the moderate group and 28% in the severe group, and the hygienist for 27% of the moderate group and 46% of the severe group. It was the assistant for 13% of the moderate group and 9% of the severe group. Thirteen percent in each group didn’t know. “Deep Cleanings” with anesthesia were reported by 46% of the moderate group and 62% of the severe group.

Based on memory, 78% of the patients reported fewer than four “cleanings” in the past two years. The study authors found fault with the general dentists for not providing at least two “cleanings” per year for these patients with periodontal disease. This is strange considering the preponderance of research demonstrating that a “cleaning” will not treat periodontal disease. Research these authors quoted was for the importance of maintenance after periodontal treatment, not prior to treatment.

Clinical Implications: What would your patients report about the care provided in your practice? It’s not always what happened, what you told them or what you assumed they understood. When referring a patient to a periodontist, be sure to send a report covering pre-referral periodontal treatment you provided and the reason for referral.

Dockter, K., Williams, K., Bray, K., Cobb, C.: Relationship Between Prereferral Periodontal Care and Periodontal Status at Time of Referral. J Perio 77: 1708-1716, 2006.