Evidence based recommendations to improve the children oral health in Saudi Arabia.

Aim: Identify the existing evidence base with regards to interventions that address high levels of dental caries. A discussion of the applicability of the evidence to possible replication in Saudi Arabia is presented, alongside recommendations to help reduce dental caries rates in children in Saudi Arabia. Methods: A comprehensive systematic review following PRISMA methods was conducted using three databases: MEDLINE via OVID; EMBASE via OVID and Cochrane Library. Studies were included according to inclusion criteria. AMSTAR2 was used to assess the quality of the included studies, while GRADE was used to assess the quality of evidence. Results: Ten studies were included in this review. The quality of these were 'high' (in two review), moderate (in two studies), low (in one study) and to 'critically low' (5 reviews). The quality of the evidence presented by the reviews ranged from 'moderate' to 'very low'. The interventions methods included MI, one-to-one nutrition advice, educational interventions and dental screening. The applicability of the findings in relation to dental care in Saudi Arabia is discussed and summarized in a narrative. Conclusion: No strong evidence that supported interventions to improve the child oral health in Saudi Arabia was found. None of the included reviews included studies conducted in Saudi Arabia or evaluated interventions among the local community. As for different culture values, norms, beliefs and attitude to those demographics explored in the reviews, it is unclear if interventions with improve oral health among Saudi children. Further research is needed to explore the efficacy of these interventions in a Saudi context.

Influence of surface and heat treatments on the flexural strength of a glass-infiltrated alumina/zirconia-reinforced dental ceramic.

OBJECTIVES: The purpose of this study was to investigate the influence of sandblasting, grinding, grinding orientation and polishing before and after heat treatment, on the flexural strength of a glass-infiltrated alumina/zirconia-reinforced dental ceramic (In-Ceram Zirconia). METHODS: The uniaxial flexural strength was calculated on 160 bar-shaped specimens (20 x 4 x 1.2mm) divided equally into eight groups as follows: sandblasted; sandblasted heated; polished; polished heated; ground parallel to the tensile axis; ground parallel heated; ground perpendicular; and ground perpendicular heated. Data were analyzed with multiple regression analysis, one-way ANOVA and Tukey's pairwise multiple comparisons and Weibull analysis. The treated and fractured surfaces were observed with SEM. The relative content of the monoclinic phase was quantified with an X-ray diffraction analysis. RESULTS: A thin layer of glass was present on the surface of the specimens after heat treatment and contributed to an improvement of the flexural strength. Surface treatment (not followed by heat treatment) generated phase transformation which, however, was not sufficient to avoid strength degradation caused by the flaws introduced with the surface treatments. Sandblasting caused the most marked strength degradation. Polishing alone increased the reliability, but did not improve the strength. The orientation of grinding in respect of the direction of the tensile stresses did not influence the ultimate tensile strength. SIGNIFICANCE: The present study suggests that any surface treatment performed on In-Ceram Zirconia should always be followed by heat treatment to avoid strength degradation.

Influence of surface and heat treatments on the flexural strength of Y-TZP dental ceramic.

OBJECTIVE: The aim of the investigation was to assess the influence of sandblasting, grinding, grinding orientation, polishing and heat treatment on the flexural strength of a yittria stabilized tetragonal zirconia polycrystals ceramic (Y-TPZ). METHODS: The specimens (160 beams) were equally divided into four groups according to the surface treatment (sandblasted, polished, ground parallel to the tensile axis, ground perpendicular). Twenty specimens from each group underwent heat treatment under the firing conditions used to fire a layer of porcelain and glaze. After treatment, the three-point flexure test was used to calculate the flexural strength and X-ray diffraction analysis was used to estimate the relative amount of monoclinic phase. The reliability of strength was assessed through the Weibull distribution. Statistical analysis was conducted with multiple regression analysis, one-way ANOVA and Tukey's pairwise multiple comparisons. Treated and fractured surfaces were observed with SEM. RESULTS: The following values of strength and relative content of monoclinic phase of zirconia were measured for each group: sandblasted (1540MPa; 9.5%); ground parallel (1330MPa; 8.3%); ground perpendicular (1525MPa; 8.3%); ground parallel and heated (1225MPa; monoclinic content not detectable); ground perpendicular and heated (1185MPa; monoclinic content not detectable); polished and heated (1165MPa; monoclinic content not detectable); polished (1095MPa; 0.8%); sandblasted and heated (955MPa; 0.3%). CONCLUSIONS: The present study suggests that sandblasting and grinding may be recommended to increase the strength of dental Y-TZP, provided they are not followed by heat treatment. Fine polishing may remove the layer of compressive stresses and therefore, lower the mean flexural strength.

Influence of hot pressing on the microstructure and fracture toughness of two pressable dental glass-ceramics.

Empress 1 and Empress 2 are well-known pressable all-ceramic dental materials that have generated substantial interest for many clinicians and patients. These two materials are reputed to benefit from heat pressing during the laboratory fabrication procedures, leading to better crystal distribution within a glass matrix, and hence an improved strength. The present study aimed to evaluate the effect of heat pressing on fracture toughness, microstructural features, and porosity. Results showed that Empress 1 had similar fracture toughness values before the pressing procedure, after it, and after the repressing procedure. The microstructural features were also similar among these specimens, but a more uniform distribution of leucite crystals was observed following the pressing and repressing procedures. Empress 2 demonstrated two different fracture toughness values. This was associated with the alignment of lithium disilicate crystals that occurred after the pressing and repressing procedures, which led to different indentation induced crack lengths, depending upon whether cracks propagated parallel to or perpendicular to the aligned crystals, the former having lower toughness than those that propagated in the perpendicular direction. Porosity, in terms of both the size and number of pores, was found to decrease after the pressing and repressing procedures for both materials. Repressing resulted in significant growth of the lithium disilicate crystals in Empress 2, but there was no change for the leucite crystals in Empress 1. The change in the lithium disilicate crystals' size did not have a noticeable effect on the fracture toughness of Empress 2. It was concluded that heat pressing did not significantly affect the fracture toughness of Empress 1, but resulted in two different values for Empress 2. It also decreased the size and number of pores for both materials, which could contribute to the strength improvement found after heat pressing, which has been reported in previous studies.

Biaxial flexural strength and microstructure changes of two recycled pressable glass ceramics.

PURPOSE: This study evaluated the biaxial flexural strength and identified the crystalline phases and the microstructural features of pressed and repressed materials of the glass ceramics, Empress 1 and Empress 2. MATERIALS AND METHODS: Twenty pressed and 20 repressed disc specimens measuring 14 mm x 1 mm per material were prepared following the manufacturers' recommendations. Biaxial flexure (piston on 3-ball method) was used to assess strength. X-ray diffraction was performed to identify the crystalline phases, and a scanning electron microscope was used to disclose microstructural features. RESULTS: Biaxial flexural strength, for the pressed and repressed specimens, respectively, were E1 [148 (SD 18) and 149 (SD 35)] and E2 [340 (SD 40), 325 (SD 60)] MPa. There was no significant difference in strength between the pressed and the repressed groups of either material, Empress 1 and Empress 2 (p > 0.05). Weibull modulus values results were E1: (8, 4.7) and E2: (9, 5.8) for the same groups, respectively. X-ray diffraction revealed that leucite was the main crystalline phase for Empress 1 groups, and lithium disilicate for Empress 2 groups. No further peaks were observed in the X-ray diffraction patterns of either material after repressing. Dispersed leucite crystals and cracks within the leucite crystals and glass matrix were features observed in Empress 1 for pressed and repressed samples. Similar microstructure features--dense lithium disilicate crystals within a glass matrix--were observed in Empress 2 pressed and repressed materials. However, the repressed material showed larger lithium disilicate crystals than the singly pressed material. CONCLUSIONS: Second pressing had no significant effect on the biaxial flexural strength of Empress 1 or Empress 2; however, higher strength variations among the repressed samples of the materials may indicate less reliability of these materials after second pressing.

Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part I. Pressable and alumina glass-infiltrated ceramics.

OBJECTIVE: The present study, divided into two parts, aimed to compare the strength, fracture toughness and microstructure of a range of all-ceramic materials. In part I, three hot-pressed glass-ceramics (IPS-Empress, Empress 2 and a new experimental ceramic) and alumina glass-infiltrated ceramics (In-Ceram Alumina), processed by both slip casting and dry pressing, were compared. METHODS: Tensile strength was appraised on 10 bar-shaped specimens (20 x 4 x 1.2 mm3) for each material with the three-point bending method; the fracture toughness was measured from 20 specimens (20 x 4 x 2 mm3), by using the indentation strength technique. Data were compared with ANOVA and the Sheffé post hoc test (p = 0.05). The volume fraction of each phase, the dimensions and shapes of the grains, porosity and the crack patterns were investigated using SEM. RESULTS: The average and standard deviation in strength (MPa) and fracture toughness (MPa m(1/2)) were: IPS-Empress 106(17)1, 1.2(0.14)1; Empress 2 306(29)2, 2.9(0.51)2, new experimental ceramic 303(49)2, 3.0(0.65)2, In-Ceram Alumina dry-pressed 440(50)2, 3.6(0.26)2, In-Ceram Alumina slip 594(52)3, 4.4(0.48)3. Values with the same superscript number showed no significant statistical difference. Microscopy revealed the relationship between the glass matrix and the crystalline phase and the characteristics of the latter were correlated to the strengthening and toughening mechanisms of these glass-ceramics. SIGNIFICANCE: The mechanical properties and microstructure of core materials have been advocated as crucial to the clinical long-term performance of all-ceramic dental restorations. This investigation provides the clinician with data regarding strength, fracture toughness and microstructure of a broad range of current materials.

Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part II. Zirconia-based dental ceramics.

OBJECTIVE: The present study is the second part of an investigation of strength, fracture toughness and microstructure of nine all-ceramic materials. In the present study, DC Zirkon, an experimental yttria partially stabilized zirconia, In-Ceram Zirconia slip and In-Ceram Zirconia dry-pressed were compared. METHODS: Strength was appraised on ten bar-shaped specimens for each material (20 x 4 x 1.2 mm) with the three-point bending method. The fracture toughness (Indentation Strength) was measured on twenty specimens (20 x 4 x 2 mm) for each ceramic. The volume fraction of each phase, the dimensions and shapes of the grains and the crack pattern were investigated with SEM. Phase transformation was investigated with X-ray diffraction. Data were compared with an ANOVA and Sheffé post hoc test (p = 0.05). RESULTS: Means of strength (MPa) and fracture toughness (MPa m(1/2)) values and their standard deviation were: In-Ceram Zirconia dry-pressed 476 (50)1, 4.9 (0.36)1; In-Ceram Zirconia slip 630 (58)2, 4.8 (0.50)1; the experimental yttria partially stabilized zirconia 680 (130)2, 5.5 (0.34)2; DC-Zirkon 840 (140)3, 7.4 (0.62)3. Values with the same superscript number showed no significant statistical difference. Microscope investigation and X-ray diffraction revealed the important role played by the tetragonal to monoclinic phase transformation and by the relationship between the glassy matrix and the crystalline phase in the strengthening and toughening mechanisms of these ceramics. SIGNIFICANCE: the zirconia-based dental ceramics are stronger and tougher materials than the conventional glass-ceramics. Better properties can have positive influence on the clinical performance of all-ceramic restorations.

Effect of sandblasting, grinding, polishing and glazing on the flexural strength of two pressable all-ceramic dental materials.

OBJECTIVES: During laboratory fabrication procedures and/or clinical adjustments, pressable materials: IPS Empress and Empress 2, may be ground, polished or sandblasted. These treatments may affect their strength by introducing microscopic flaws and defects. This study investigates the effect of these procedures on the mean flexural strength of these materials. METHODS: One hundred and forty disc specimens (14mmx1 mm) of IPS Empress and Empress 2 were prepared, and divided into seven groups of 20 specimens for each material. Groups were untreated, polished, polished and glazed, ground, ground and glazed, sandblasted, sandblasted and glazed. Surface roughness, mean biaxial flexural strength and Weibull modulus were appraised, and a scanning electron microscope was used to describe surface features. Statistical significance among groups of population was analysed using one-way Anova and Tukey's multiple comparison tests. RESULTS: Untreated and sandblasted groups showed significantly the highest roughness values, and polished the lowest for each material (p<0.05). Ground groups showed significantly lower roughness values than the sandblasted groups, and significantly higher roughness than the polished groups for each material (p<0.05). Polished groups for each material demonstrated significantly the highest mean flexural strength values (p<0.05). No significant difference in the mean strength values was found between untreated, sandblasted and ground groups for each material (p>0.05). Heat treatment had no effect on roughness or strength values of all treated groups of both materials. The Weibull modulus values for both materials varied with different treatments. They showed higher values for polished and untreated groups, and lower values for ground and sandblasted groups. CONCLUSIONS: Surface roughness may not be the only feature that determines strength. Other issues such as porosity, microstructural residual stresses, surface and bulk defects may also be pertinent.

Influence of grinding, sandblasting, polishing and heat treatment on the flexural strength of a glass-infiltrated alumina-reinforced dental ceramic.

The influence of processing-introduced flaws and heat treatment on the strength degradation of the dental core material has recently been observed. However, there are insufficient studies which investigate the role of grinding, grinding orientation, sandblasting, polishing and heat treatment on the strength of In-Ceram Alumina (IA), one of the most used glass-infiltrated alumina-reinforced dental core ceramics. To address these issues, the uniaxial flexural strength and reliability of eight groups of specimens (sandblasted, ground parallel to the tensile axis, ground perpendicular, and polished with and without heat treatment) were assessed. Statistical analyses indicate that heat treatment significantly improved the flexural strength of the material regardless of the surface treatment. Conversely, any surface treatment caused strength degradation, if it was not followed by heat treatment. Sandblasting caused the most marked strength degradation. Polishing alone (without heat treatment) did not strengthen the ceramic. The orientation of grinding in respect of the direction of the tensile stresses did not influence the ultimate tensile strength. The present study suggests that, in the case of IA, sandblasting, grinding and polishing should always be followed by heat treatment in order to avoid strength degradation of the material.

Fracture toughness and hardness evaluation of three pressable all-ceramic dental materials.

OBJECTIVES: This study evaluates the fracture toughness and hardness of three pressable all-ceramic materials: IPS-Empress, Empress 2 and an experimental ceramic material. METHODS: Fifteen discs and 15 bars per material were prepared. Fracture toughness was measured with two different techniques: indentation fracture and indentation strength. During the indentation fracture tests the hardness of each material was also measured. Statistical significance among groups of population was studied using one-way Anova and Tukey's multiple comparison tests. RESULTS: Fracture toughness results using the indentation strength technique (with three-point bending and biaxial flexure tests) were: IPS-Empress (1.39 (SD 0.3) and 1.32 (SD 0.3)); Empress 2 (3.14 (SD 0.5) and 2.50 (SD 0.3)) MPa x m(1/2); and the experimental ceramic (3.32 (SD 0.6) and 2.43 (SD 0.3)) MPa x m(1/2). The indentation fracture technique generated orthogonal cracks of different lengths for Empress 2 and the experimental ceramic, whether perpendicular or parallel to the lithium disilicate elongated crystals. Thus, two values were reported: Empress 2 (1.5 (SD 0.2) and 1.16 (SD 0.2)) MPa x am(1/2) and the experimental ceramic (1.67 (SD 0.3) and 1.15 (SD 0.15)) MPa x m(1/2). The IPS-Empress indentation fracture result was 1.26 (SD 0.1). The hardness results were: 6.6, 5.3 and 5.5 GPa for IPS-Empress, Empress 2 and the experimental ceramic, respectively. CONCLUSIONS: No significant differences in fracture toughness and hardness results were found between Empress 2 and the experimental ceramic (P>0.05 ANOVA). Both materials exhibited fracture toughness anisotropy following pressing. They demonstrated improved fracture toughness and reduced hardness compared with IPS-Empress P<0.05(ANOVA), which should be beneficial for clinical applications.

Biaxial flexural strength, elastic moduli, and x-ray diffraction characterization of three pressable all-ceramic materials.

STATEMENT OF PROBLEM: Before the release of an advanced ceramic material, independent assessment of its strength, elastic modulus, and phase composition is necessary for comparison with peer materials. PURPOSE: This study compared the biaxial flexural strength, elastic moduli, and crystalline phases of IPS Empress and Empress 2 with a new experimental ceramic. MATERIAL AND METHODS: Twenty standardized disc specimens (14 x 1.1 mm) per material were used to measure the biaxial strength. With a universal testing machine, each specimen was supported on 3 balls and loaded with a piston at a crosshead speed of 0.5 mm/min until fracture. Three standardized bars (30 x 12.75 x 1.1 mm) for each material were prepared and excited with an impulse tool. The resonant frequencies (Hz) of the bars were used to calculate the elastic moduli with the equation suggested by the standard ASTM (C 1259-94). X-ray diffraction with Cu Kalpha at a diffraction angle from 20 to 40 degrees was used to identify the crystalline phases by means of a diffractometer attached to computer software. The data were analyzed with 1-way analysis of variance followed by pairwise t tests (P<.05). RESULTS: Mean biaxial strengths were 175 +/- 32, 407 +/- 45, and 440 +/- 55 MPa for IPS Empress, Empress 2, and the experimental ceramic, respectively. Elastic modulus results were 65, 103, and 91 GPa for the same materials, respectively. There was no significant difference in strength and elastic modulus between Empress 2 and the experimental ceramic. Both materials demonstrated a significantly higher elastic modulus and strength than IPS Empress. X-ray diffraction revealed leucite as the main crystalline phase for IPS Empress and lithium disilicate for both Empress 2 and the experimental ceramic. CONCLUSION: Within the limitations of this study, the improved mechanical properties of Empress 2 and experimental ceramic over those of IPS Empress were attributed to the nature and amount of their crystalline content lithium disilicate.

Mechanical properties of In-Ceram Alumina and In-Ceram Zirconia.

PURPOSE: This study compared the mechanical properties of In-Ceram Zirconia and In-Ceram Alumina. MATERIALS AND METHODS: Ninety-four disks and six bars were prepared with the slip-casting technique. The disks were used to assess biaxial flexural strength (piston on three ball), Weibull modulus, hardness, and fracture toughness with two methods: indentation fracture and indentation strength. The bars were used to measure elastic moduli (Young's modulus and Poisson's ratio). X-ray diffraction analysis of the specimens was carried out upon every step of the specimen preparation and of the fractured surfaces. RESULTS: Mean biaxial flexure strengths of In-Ceram Alumina and In-Ceram Zirconia were 600 MPa (SD 60) and 620 MPa (SD 61), respectively. Mean fracture toughness measured according to indentation strength was 3.2 MPa.m1/2 (SD 0.34) for in-Ceram Alumina and 4.0 MPa.m1/2 (SD 0.43) for In-Ceram Zirconia. Mean fracture toughnesses of In-Ceram Alumina and In-Ceram Zirconia measured according to indentation fracture were 2.7 MPa.m1/2 (SD 0.34) and 3.0 MPa.m1/2 (SD 0.48), respectively. X-ray diffraction analysis showed that little phase transformation from tetragonal to monoclinic occurred when the specimens were fractured, supporting the existence of a modest difference of fracture toughness between the two ceramics. CONCLUSION: No statistically significant difference was found in strength. In-Ceram Zirconia was tougher (P < .01) than In-Ceram Alumina when tested according to indentation strength. However, no significant difference was found in the fracture toughness when tested with the indentation fracture technique.