New insights from Raman MicroSpectroscopy and Scanning Electron Microscopy on the microstructure and chemical composition of vestibular and lingual surfaces in permanent and deciduous human teeth.

Teeth are characterized by a specific chemical composition and microstructure, which are related to their nature, permanent and deciduous, and to the sides, lingual and vestibular. Deeper knowledge in this topic could be useful in clinical practice to develop new strategies in restorative dentistry and in the choice of materials with the best performances. In this study, Raman MicroSpectroscopy (RMS), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometry (EDS), and Vickers MicroHardness (VMH) were exploited to: (1) identify the microstructure and the chemical/elemental composition of permanent and deciduous human teeth, also characterizing their lingual and vestibular sides, and (2) validate a new multidisciplinary analytical approach, for obtaining multiple information on calcified tissues. All applied techniques evidenced differences between permanent and deciduous teeth both in the lingual and vestibular sides. In particular, scanning electron micrographs identified areas with an irregular appearance in the vestibular and lingual sides, which presented also different VMH values. Moreover, RMS and EDS displayed a different chemical/elemental composition in outer and inner enamel and dentin, in terms of Mineral/Matrix, Crystallinity, Carbonates/phosphates, and concentrations by weight (%) of calcium, phosphorous, carbon, magnesium, and sodium. A good linear correlation was found between RMS spectral profiles and EDS and VMH measurements, suggesting that RMS may be considered a useful and non-destructive diagnostic tool for obtaining multiple information on calcified tissues.

A 3-day randomized clinical trial to investigate the desensitizing properties of three dentifrices.

BACKGROUND: The aim of the present study is to evaluate the relative abilities of three desensitizing dentifrices to provide rapid relief of dentin hypersensitivity (DH). METHODS: Using a double-mask, randomized design, three dentifrices: 1) containing 8% arginine and 1,450 ppm sodium monofluorophosphate; 2) containing 8% strontium acetate and 1,040 ppm sodium fluoride; and 3) containing 30% microaggregation of zinc-carbonate hydroxyapatite nanocrystals were compared after 3-day treatment. Participant's DH was evaluated at baseline and after 3 days using air-blast, tactile, cold water, and subjective tests. RESULTS: The final sample consisted of 85 individuals: 29 received the arginine-based dentifrice (group 1), 27 the strontium acetate-based dentifrice (group 2), and 29 the dentifrice based on zinc-carbonate hydroxyapatite (group 3). All dentifrices were mostly effective to reduce DH: the percentage of score reduction from baseline to 3 days was >30% for all tests (except for subjective test of group 2). The comparison among the three dentifrices showed that, after 3 days, there was an improvement in air-blast (mean percentage of reduction, 39.2% in group 1, 42.0% in group 2, and 39.2% in group 3), cold water (41.5%, 51.8%, and 50%), tactile (50.3%, 40.1%, and 33.8%), and subjective (33.1%, 17.4%, and 31.4%) test scores, with differences being significant for cold water and subjective tests. For air-blast and tactile tests, there were no significant differences across groups at 3 days. Moreover, no significant differences at any test were observed in a subset of patients that were followed up to 8 weeks: all dentifrices were all highly efficacious. CONCLUSIONS: This study documents that the three tested dentifrices significantly reduced DH after 3-day treatment, supporting their use in clinical practice. To the best of the authors' knowledge, this is the first report documenting the rapid relief from DH of a zinc-carbonate hydroxyapatite dentifrice.

A double-blind randomized-controlled trial comparing the desensitizing efficacy of a new dentifrice containing carbonate/hydroxyapatite nanocrystals and a sodium fluoride/potassium nitrate dentifrice.

BACKGROUND AND AIM: Several dentifrices have shown to be effective in reducing dentine hypersensitivity (DH), but more effective products are needed. The aim of the study was to evaluate the desensitizing efficacy of a new dentifrice based on zinc-carbonate hydroxyapatite (CHA) nanocrystals. METHODS AND MATERIALS: Using a double-blind, randomized design, the new dentifrice was compared with potassium nitrate/fluoride dentifrice (active control). The participant's DH was evaluated at baseline and after 4 and 8 weeks using airblast (primary outcome), tactile, cold water and subjective tests (secondary outcomes). RESULTS: The final sample consisted of 70 subjects with baseline DH; 36 received the new dentifrice and 34 the control one. Both dentifrices were largely effective; the percentage of score reduction from baseline to 8 weeks was greater than 28% for all tests (and greater than 55% for the cold water test) in both groups. As compared with controls, experimental subjects had a significantly greater improvement in the airblast test score (mean percentage of reduction of 46.0%versus 29.4% in controls) and the subjective test score (47.5%versus 28.1%, respectively), with both differences already being significant after 4 weeks. In contrast, there was no significant difference between groups for either the tactile or cold water tests at any time point and with any outcome. CONCLUSIONS: This study documented that the new dentifrice containing zinc-CHA nanocrystals significantly reduced dentinal hypersensitivity after 4 and 8 weeks, supporting its utility in clinical practice.

Long-term clinical results on the use of bone-replacement grafts in the treatment of intrabony periodontal defects. Comparison of the use of autogenous bone graft plus calcium sulfate to autogenous bone graft covered with a bioabsorbable membrane.

BACKGROUND: Many clinical investigations have demonstrated the benefits of different regenerative approaches in the treatment of infrabony defects. The aim of this investigation was to evaluate the results obtained with the combination of autogenous bone grafting plus calcium sulfate and to compare this outcome with the results obtained using autogenous bone grafting with a bioabsorbable membrane. METHODS: Twelve subjects participated in this split-mouth trial. Twelve 2- or 3-wall periodontal defects were treated with a combination of autogenous bone grafting plus calcium sulfate (test) and were compared to 12 defects treated with autogenous bone grafting with a bioabsorbable membrane (control). Before surgery, subjects were instructed in oral hygiene techniques, and scaling and root planing were completed. Surgery was identical for both groups except for the regenerative material. After healing, subjects followed a periodontal maintenance program. Probing depth (PD), clinical attachment level, and bleeding on probing were recorded at baseline, 6 months, and 6 years. RESULTS: There were no statistical differences between test and control defects at baseline. At 6 months, there was a PD reduction of 4.3 +/- 1.0 mm in the control group and 4.4 +/- 1.1 mm in the test group. There was a clinical attachment gain of 3.5 +/- 1.1 mm in the control group and 3.6 +/- 1.0 mm in the test group. At 6 years, there was a PD reduction of 3.3 +/- 1.0 mm in the control group and 4.2 +/- 1.2 mm in the test group. There was a clinical attachment gain of 2.6 +/- 1.2 mm in the control group and 2.4 +/- 1.1 mm in the test group. Differences between treatment groups were not statistically significant at 6 months or 6 years. CONCLUSION: Both therapies led to significant short- and long-term improvements in the outcome variables assessed.

Effect of margin design on the fracture resistance of Procera all ceram cores: an in vitro study.

AIM: The aim of the present in vitro study is to compare the resistance to fracture under a cyclic load applied to chamfer-edged vs. shoulder-edged Procera All Ceram cores. MATERIALS AND METHODS: An extracted first maxillary premolar was prepared with a 50 degrees chamfer margin using conventional diamond burs, and an impression was taken using a polyvinylsiloxane. The impression was poured ten times using resin to fabricate dies. The same tooth was retrieved and the 50 degrees chamfer was converted into a 90 degrees shoulder by means of an appropriate diamond bur. An impression was taken and ten more resin dies were fabricated. The resin dies were cast using the lost wax technique in order to obtain brass copies. Impressions of each brass die were taken using a polyvinylsiloxane impression material and poured with die stone. The stone dies were sent to a dental laboratory where densely sintered alumina cores 0.4 mm thick were fabricated using a CAD/CAM process. The alumina cores were then cemented on the brass dies and underwent a fracture test with a cyclic load for 24 hours. Fragments were retrieved for fracture characterization using scanning electron microscopy (SEM). RESULTS: The mean values of fracture resistance for the chamfer samples were 406.10 +/- 67.271 N and 643.90 +/- 32.912 N for the shoulder samples. The Student's t-test revealed a statistically significant difference between groups. CONCLUSIONS: The results of this in vitro study indicate a relationship between the cervical thickness of the alumina cores and their fracture resistance. A shoulder margin could improve the biomechanical performance of posterior single crown alumina restorations.

Peri-implant bone regeneration with calcium sulfate: a light and transmission electron microscopy case report.

BACKGROUND: Calcium sulfate is a simple, biocompatible material with a very long, safe clinical history in several different fields of medicine. It is a rapidly resorbing material that leaves behind calcium phosphate lattice, which promotes bone regeneration. OBJECTIVE: The aim of this study was a histological and ultrastructural evaluation of the tissues in a peri-implant site regenerated with calcium sulfate. MATERIALS AND METHODS: The specimens were processed for observation under light and transmission electron microscopes. RESULTS: In light microscopy, trabecular bone was present. No remnants of calcium sulfate were present. Transmission electron microscopy showed, in the areas of the interface with the implant surface, features of mature bone with many osteocytes. An amorphous layer and/or osteoid seam separated this mature bone from the metal surface. CONCLUSION: The results confirm the high biocompatibility and rapid resorption of calcium sulfate.

Bone regeneration with calcium sulfate: evidence for increased angiogenesis in rabbits.

Autologous bone is the preferred bone graft material because it carries proteins as bone-enhancing substrates, minerals, and vital bone cells. Calcium sulfate (CS) is a well-tolerated, biodegradable, osteoconductive bone graft substitute and is a reasonable alternative to autogenous bone graft. Blood vessels are an important component of bone formation and maintenance. The process of vascular induction is called angiogenesis, and it plays a key role in all regenerative processes. Bone tissue differentiation is related to the local presence of blood vessels. One method to evaluate the presence of blood vessels in a tissue is to count the microvessels to evaluate microvessel density (MVD). The aim of the present study was to conduct a comparative evaluation of microvessel density in sites treated with CS and autologous bone in rabbits, with or without e-PTFE nonresorbable membranes (Gore-Tex, Flagstaff, Ariz). Nine New Zealand rabbits, each weighing about 2.5 kg, were used in this experiment. Three 6-mm wide defects were created in each tibial metaphysis. The defects were filled in a random way. The defects of group 1 (3 rabbits) were filled with CS granules (Surgiplaster, Classimplant, Rome, Italy) and covered with e-PTFE membranes. The defects in group 2 (3 rabbits) were filled with CS granules (Surgiplaster). The defects in group 3 (3 rabbits) were filled with autologous bone. A total of 54 defects were filled (18 with CS and e-PTFE membranes, 18 with CS alone, and 18 with autologous bone). No postoperative deaths or complications occurred. All nine animals were sacrificed at 4 weeks. MVD results were as follows: in the first group, 9.88 +/- 4.613; in the second group, 7.92 +/- 1.998; and in the third group, 5.56 +/- 1.895. P = .000 was highly significant. Statistically significant differences were found between groups 1 and 3, 1 and 2, and 2 and 3. The presence of more blood vessels in the sites treated with CS could help to explain the good results reported in the literature with the use of CS.