Materials: We used 5 alginates (Alginplus Tropical “A”, Alginmax “B”, Alginmajor “C”, Alginkid Orthodontic “D”, Alginplus Fast “E”, Major Dental, Moncalieri-To, Italy, www.majordental.com) for impressions to develop models for orthodontic studies.
Methods: Fifty patients “special-needs kids-down syndrome” took part in our group; there were two operators: one orthodontist was assigned to mixing and the second one was assigned to setting. Each patient had two impressions, for a total of 100 impressions (20 impressions for each alginate). The producer's instruction was to develop impressions at 23°C of atmosphere and defined quantities, which we respected. We decided to use the same temperature for water,4°C.
For each alginate we developed a quality evaluation defined by five features: mixing, water absorption,consistency, processing time, curing time,and a total final evaluation.
For each feature we considered two degrees of quality:POSITIVE, favourable for working time; NEGATIVE, not favourable for working time.
In our clinical practice with special-needs kids we need very short working time.
Results: The comparison shows no significant clinical differences among our alginates.
• Mixing: positive
• Water absorption: positive
• Consistency: positive
• Processing time: positive
• Curing time: positive, the best for alginate “D” (1'50'')
Total final evaluation: positive
Conclusion: The differences are not significant to guide us in a specific choice of one of these alginates. The only one important feature is curing time because of kind of our patients: “special-needs kids”, who have a poor and very short in time collaboration for invasive dental procedures in comparison with normal people.