Dental photography today. Part 1: basic concepts.

This paper is the first article in a new series on digital dental photography. Part 1 defines the aims and objectives of dental photography for examination, diagnosis and treatment planning, legal and forensic documentation, publishing, education, marketing and communication with patients, dental team members, colleagues and dental laboratory.

Traditional elastic ligatures versus slide ligation system. A morphological evaluation.

OBJECTIVE: Elastomeric materials play an important role in the orthodontic practice, including the retraction force to move teeth into extraction sites, closing diastemas, selective shifting of the midline and generalized space closure. Frictional resistance and ligating strength of archwire-bracket-ligature complex occurs during utilization of elastomeric and metallic ligatures when orthodontic forces are applicated. The aim of this study was to analyze elastic deformation of three types of elastomeric ligatures, after clinical use. MATERIAL AND METHODS: ELASTOMERIC LIGATURES: ring-shape, transparent, latex ligatures (Leone® S.p.A.), ring-shape, grey, polyurethane ligatures (Micerium® S.p.A.) and grey, polyurethane, Slide low-friction ligatures (Leone® S.p.A.). A total of 9 orthodontic patients undergoing fixed orthodontic therapy were selected. Three specimens were applied, one for each types of ligature, inside the oral cavity of each subject. Samples were kept in the oral cavity for 28 days, ligating 0.16 X 0.22 inches stainless steel archwires to stainless steel premolars brackets (Leone® S.p.A., Sesto Fiorentino, FI, Italy) for Bidimensional technique. After the pre-established time, the systems of ligature were removed and washed. Control group consisted of 9 unused specimens of each ligation type. Each elastomeric ligature was observed under the scanning electron microscope (SEM) to determine variations in size. The archwire-bracket-ligature complex was also analyzed. RESULTS: Transparent O-ring ligatures showed significant volumetric and structural changes. The external rounded shape was rather maintained, while the internal shape tended to appear square. Both external and internal diameter significantly increased (p<0.005 and p<0.0001 respectively) while the thickness decreased ( p<0,005) when analyzed with t-test. Polyurethane ring-shape ligatures retained the initial ring design. Both external and internal diameter increased (p<0.0001), while the thickness remained almost unchanged. The internal border was more squared, and showed jagged edges with continuous and irregular extroversions. Grey, polyurethane Slide low-friction ligatures showed a reduced dimensional change. There was a slight increase in two dimensions, length and width, (14-16%) (p<0.05 and p<0.001) while there was a not significant decrease in thickness (10%). CONCLUSION: From SEM analysis of ligature morphology it emerges that latex and polyurethane O-ring ligatures endure significant volumetric and structural changes, after clinical use, index of a greater degree of friction and early loss in functionality. Grey, polyurethane Slide low-friction ligatures presented limited variation in size after clinical use.

Plaque retention on elastomeric ligatures. An in vivo study.

UNLABELLED: Fixed orthodontic appliances make it difficult to maintain the oral hygiene, resulting in plaque accumulation. Retention of bacterial plaque, represents a risk for white spot lesions and development of periodontal disease. AIM: Purpose of this study was to determine in vivo the retention of plaque on three different elastic ligatures, in comparison with stainless steel ligature, to determine a possible association between type of ligatures and accumulation of microorganisms. MATERIAL AND METHODS: THREE ELASTIC LIGATION SYSTEMS WERE ANALYZED FOR PLAQUE RETENTION: ring-shape, clear, latex ligatures (Leone® Spa), ring-shape, grey, polyurethane ligatures (Micerium® Spa) and grey, polyurethane, Slide low-friction ligatures (Leone® Spa), compared with stainless steel ligatures (Leone® Spa) used as control. Forthy orthodontic patients undergoing fixed orthodontic therapy were selected. A sample for each type of ligature were applied inside the oral cavity of each subject. Samples were kept in the oral cavity for 28 days, ligating 0.16 X 0.22 stainless steel archwire to stainless steel orthodontic premolars brackets. The presence of bacterical slime was quantified by spectrophotometric method (crystal violet-Bouin's fixative) and morphological observations was evaluated by Scanning Electron Microscopy (SEM). RESULTS: From analysis of bacterical slime emerges that all the elastics showed a low plaque retention, especially if compared to the group of steinless steel ligatures, that presented a greater plaque adhesion, statistically significant compared to the Slide group (r<0.0002) and the two elastic groups (r<0.0001). This study reported no significant difference between the Slide ligatures and the traditional elastic ligatures as regards the retention of plaque. SEM images showed presence of cocci, rods and few filamentous organisms and an interbacterial matrix in all observed samples. CONCLUSION: Elastomeric ligatures showed a significant lower susceptibility to plaque adhesion, in comparison to the stainless steel of the metallic ligatures. No statistically significant difference was observed among the elastic devices.

Morphological observations and Fractological considerations on orthodontics miniscrews.

AIM: The purpose of this study was to evaluate morphological and biomechanical characteristics of a commercial mini-implant. METHODS: Orthodontic low head mini implants, in the two available sizes of 1.5 and 2 mm, have been used. The electronic scanning microscope evaluation has been tested on 3 groups each one composed of 4 samples, observed in numerous enlargements and in the three dimensions of the space. The groups were composed of new mini implants, undamaged mini implants observed after their clinical use and mini-implants broken at the moment of their insertion or removal after their therapeutical use. RESULTS: The microscope analysis of unused mini implants has shown how the diameter reduction of the neck represents the area of greater weakness; such parameter is very important in determining screw resistance to fracture. In fact the fracture observed in vivo always happened to this degree. Some micro carvings and cracks were shown on the surface, these irregularities could facilitate or promote the enlargement of the cracking itself. CONCLUSION: From the results obtained it is clear that the steel is adequate for permanence in the oral cavity, and moreover the material itself is adapted to bear the pressure put on it during therapy. However, it remains advisable to make certain changes to better the surface and geometry of the miniscrews.

SEM analysis of zirconium brackets using MIM technology.

AIM: The need to be able to use a material with esthetic characteristics of ceramic and mechanical properties of the metallic brackets has led clinical and industrial research towards the realization of zirconium brackets. These brackets seem to respond to both the requirements of new esthetic concepts and of interesting biomechanical qualities: hardness, resistance to abrasion, resistance to compression, reduced coefficient of friction during mechanical sliding, stability in a humid temperature and to the aggression of oral fluids. METHODS: Twenty samples of zirconium brackets have been observed at SEM realized using the metal injection molding (MIM) technology: 10 new ones used as base samples and 10 used samples with the purpose of assessing the morphologic aspect and the structural variations after clinical use. RESULTS: The comparison the samples showed some structural changes regarding the surface of the body of the brackets, while slot and wings maintain an interesting stability of construction, a moderate degree of abrasion even after the application of considerable clinical strength. CONCLUSIONS: The conclusion is drawn that the positive clinical response in the use of these brackets and the limited scientific literature on the use of zirconium in orthodontics is worthy of further research.