Comparison of in vivo and in vitro shear bond strength
Stephen D. Murray and Ross S. Hobson
When you read an article reporting the shear bond strength of a new bracket adhesive, do you wonder about the clinical applicablity of the results when the test was made in the controlled conditions of a laboratory? How would the results stand up if the same adhesive were tested in the mouth on brackets subjected to saliva, chemical and physical degradation, and erosion by food and bacterial activity? If you prefer life in the real world, you will be interested in this study. The authors compared 2 popular adhesives by bonding brackets to enamel slabs and placing the specimens (in a special appliance) in the mouths of 20 volunteers for up to 12 weeks. Bond strengths were compared with control specimens stored in sterile water over the same time periods. If you guess that the results were different, you are right. Mean bond strengths were significantly lower for the specimens placed in the mouths of volunteers than those stored in the laboratory. This study shows that we need more in vivo studies.
In vivo inhibition of demineralization around orthodontic brackets
Jasmine Gorton and John D. B. Featherstone
With promotion of the benefits of fluoride-releasing glass ionomer cements, do you ever wonder how effective they are when used on real patients—those who aren't perfect in their brushing habits? The authors of this study at UCSF found out by bonding brackets in 21 patients. Brackets were bonded to first premolars with a fluoride-releasing glass ionomer in 11 randomly assigned patients, and a composite resin (no fluoride) was used in the other 10. Four weeks later, the teeth were extracted (according to the treatment plan) and examined. The results of this in vivo study indicate that significantly more decalcification occurred around the brackets in the control patients. In those who had glass ionomer with fluoride, the cariostatic effect was localized near the brackets. When measuring whole-mouth salivary fluoride levels, no overall difference between the 2 groups was found.
Arch width after extraction and nonextraction treatment
Anthony A. Gianelly
“Patients who are treated nonextraction tend to have broader smiles” is often heard on the lecture circuit; I might even have said it myself. But does this logical-sounding utterance hold up to scientific scrutiny? Fortunately, we have a few independent thinkers around who believe the scientific method can aid our search for the truth. In a straightforward attempt at answering this question, Tony Gianelly measured anterior and posterior arch widths of 25 patients who had 4 first premolars extracted and 25 patients treated without extractions to determine which dental arches were narrower. After treatment, arch widths in both groups were statistically similar, with 1 exception: the average mandibular intercanine dimension was 0.94 mm larger in the extraction sample than in the nonextraction subjects. Notes Gianelly, “In a more global sense, the contention that extraction treatment results in less esthetic smiles because of narrowing of the dental arches is, to an extent, similar to a once-presumed damaging effect of extraction therapy on the temporomandibular joint. The available data indicate that narrow dental arches are not the expected consequence of extraction treatment.”
Orthodontic treatment considerations in patients with diabetes mellitus
Luc Bensch, Marc Braem, Kristien Van Acker, and Guy Willems
By 2010, 221 million people worldwide are expected to have diabetes mellitus (DM). When treating these patients, the practitioner must understand its consequences in relation to orthodontic care. Well-controlled DM is not a contraindication for dental treatment, but special attention is needed for periodontal problems. If signs of deterioration of the glycemic control are noticed, the orthodontist should advise the patient to consult his or her physician. This review article is well written and worth reading.
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