Primers and indirect bonding
Queiroz Tavares ML, Elias CN, Nojima LI. Effects of different primers on indirect orthodontic bonding: shear bond strength, color change, and enamel roughness. Korean J Orthod 2018;48:245-52
Bracket placement and removal are 2 of the most critical processes during orthodontic treatment, and indirect bonding is a clinical technique that has continued to rise in popularity as clinical efficiency has improved. Indirect bonding has advantages and disadvantages. The authors of this in-vitro study sought to compare shear bond strength, adhesive remnant index, and color change between self-etch and acid-etch primers, between direct and indirect bonding, and roughness of the enamel after debond between a 12-blade bur and an aluminum oxide polisher. Seventy bovine incisors were placed into 7 groups of 10: 1 control group (no bonding), 1 group with direct bonding, and 5 groups that were indirectly bonded with 5 primers (1 primer per group). All materials were bonded to the teeth according to the manufacturers’ recommendations and with Transbond XT as the adhesive. Color change was determined with a spectrophotometer after 72 hours of staining with coffee. Enamel roughness was evaluated using a rugosimeter based on the interferometry technique, which allows measurement of an infinite number of lines in a given surface area to look at surface morphology in 3 dimensions. This was the first study in orthodontics to use this technique. The results showed that Sondhi Rapid-Set and Transbond Plus self-etching primer had significantly lower shear bond strength ( P < 0.01), but may still have adequate strength in a clinical setting. Bond strength of indirect vs direct bonding was not statistically different. The results also showed that direct bonding (70% of teeth) left more enamel on the teeth than indirect bonding (0%-30% of teeth), although this was not statistically significant. The color change portion of this study yielded no differences in any bonding method or primer tested, showing that resin tags alone do not cause color changes in teeth. Enamel roughness was statistically and significantly increased in both the 12-blade bur and the aluminum oxide polisher groups from initial enamel roughness, but no statistically significant difference was found between the 2 adhesive removal methods, although the polisher had less rough enamel than the 12-blade group.
Reviewed by James Williams
Systemic medication and root resorption
Makrygiannakis MA, Kaklamanos EG, Athanasiou AE. Effects of systemic medication on root resorption with orthodontic tooth movement: a systematic review of animal studies. Eur J Orthod 2018 July 9 [Epub ahead of print]
Systemic medications may alter the body’s molecular pathways; subsequently, their use may play a role in orthodontic-related root resorption. A thorough investigation of available controlled animal studies was conducted to determine the effect of common systemic medications on orthodontic-related root resorption. A search was conducted in 8 databases, and 21 studies were selected. Root resorption was shown to occur at an increased rate in animals treated with vitamin C. Conversely, a decrease in the incidence of root resorption was seen in animals that were administered meloxicam, strontium ranelate, simvastatin, and lithium chloride. Furthermore, there was no difference in the rate of root resorption associated with acetaminophen, aspirin, atorvastatin, zoledronic acid, misoprostol, zinc, or fluoxetine. The risk of bias was unknown for 19 of the studies reviewed in the systematic review, and only 2 studies were shown to have low bias; this is a limitation when drawing conclusions. Additionally, due to the limited amount of information retrieved from the studies, analyses for “small-studies effects,” publication bias, and subgroup analysis were not possible. Thus, the available evidence was considered to be low at best. A final weakness of the studies was that root resorption is a 3-dimensional process, and most studies used 2-dimensional means to evaluate root resorption. The researchers noted that the overall quality of the evidence was low, but that it is important to be aware of the medications taken by a patient and their possible effects on orthodontic treatment.
Reviewed by Peter Pisano