Abstract
Purpose:
Effect of an erosive challenge on the surface, optical, and mechanical properties of prostheses manufactured using different types of dental ceramics for computer-aided design/computer-aided manufacturing (CAD/CAM).
Materials and Methods:
Protocol followed PRISMA guidelines. A PICO question was formulated: “What is the effect of gastric juice on the surface, optical and mechanical properties of different types of dental ceramics made using the CAD/CAM system?.” PubMed/MEDLINE, EMBASE, Web of Science, Scopus, Cochrane Library, and ProQuest was search to July 2024. The quality of the full-text articles was evaluated for Joanna Briggs Institute critical. The meta-analysis was the inverse variance method (P < 0.05).
Results:
After applying the selection criteria, 15 in vitro studies published between 2014 and 2022, 777 specimens were included. Fourteen studies were included in meta-analysis, which no significant difference in the surface roughness after the erosive challenge was observed between the ceramic types (P = 0.59; MD: 0.14; 95% confidence interval [CI]: −0.36–0.64; I2 = 86%, P < 0.01), significantly less color change was observed without the erosive challenge (P < 0.05; MD: 1.82; 95% CI: 0.86–2.79; I2 = 81%, P < 0.01), and significantly lower microhardness was observed for the groups with the erosive challenge (P = 0.03; MD: −0.95; 95% CI: −1.82–−0.08; I2 = 88%, P < 0.01).
Conclusions:
The ceramics showed changes in roughness, color stability, microhardness and flexural strength, depending on the type of ceramic.
Keywords: Computer-aided design-computer-aided manufacturing, ceramics, color, erosion, mechanical tests
INTRODUCTION
Dental ceramics are used as one of the main treatment options in oral rehabilitation owing to their excellent properties contributing to a resemblance to tooth structure and superior chemical, optical, and mechanical stability as compared with that of other restorative materials.[1,2,3] The computer-aided design/computer-aided manufacturing (CAD/CAM) in dentistry facilitated the manufacture of ceramic restorations in a single appointment, with excellent accuracy and lower cost.[4,5] The different types of ceramics manufactured by CAD/CAM are classified according to their composition: vitreous (feldspathic, leucite, lithium disilicate, and fluorapatite), polycrystalline (alumina and zirconia), and hybrid (nanoceramics, polymer-infiltrated, and zirconia-infiltrated resins).[1,4,5,6,7]
Resin-ceramics were developed to reverse limitations of vitreous and polycrystalline ceramics. Resin-ceramics are composed of a resinous matrix (polymer) with refractory inorganic compounds (ceramic particles) and have superior esthetic and resistance properties to vitreous and polycrystalline.[4,9] The properties of ceramics tend to change due to intraoral factors, such as saliva, masticatory forces, temperature, tensions, and saliva pH.[8,9,10] Normal pH of saliva (6.8–7.2) and is modified by extrinsic factors, such as excessive ingestion of acidic foods and drinks and use of drugs and pharmaceuticals, and intrinsic factors, such as gastric acid regurgitation, which can lower salivary pH.[11,12]
Patients with gastroesophageal reflux disease or disorders, such bulimia nervosa and/or anorexia, has been increasing, and the exposure of restorative materials to acidic pH has become a frequent scenario, making it a topic of paramount importance in dentistry.[13] Gastroesophageal reflux is characterized by the routine regurgitation of gastric acid from the stomach into the esophagus or oral cavity.[14,15] Gastric acid has an extremely low pH (<2.0) and is mainly composed of hydrochloric acid (HCl), making it erosive. Its potential for damage is significantly greater than that of other dietary acids.[14,16] The exposure time and pH of HCl are associated with weakening of the chemical durability and other properties of dental ceramics.[14,16,17]
Erosive wear causes surface degradation of dental ceramics through the selective leaching of alkaline ions, ultimately leading to mechanical, biological, and esthetic failures.[18] Exposure to HCl can change the surface topography of the ceramic and increase surface roughness, encouraging plaque accumulation and wear of antagonist teeth[14,19] in addition to affecting light reflection and thereby altering color perception.[6,14,20] Ceramics exposed to an acidic environment may also have decreased flexural strength, which causes stress concentration and cracks and alters fracture resistance. These alterations compromise durability and long-term restorative clinical success.[21,22,23,24]
From a clinical perspective, it is essential to be aware regarding the effects of HCl exposure on CAD/CAM ceramic restorations properties. Thus, this systematic review and meta-analysis was performed to evaluate the effect of an erosive challenge on the surface, optical, and mechanical properties of prostheses manufactured using different types of dental ceramics for CAD/CAM. The null hypothesis was that there are no statistically significant differences in the surface, optical, and mechanical properties of different CAD/CAM ceramic materials after the erosive challenge.
MATERIALS AND METHODS
Registration
This search following according to PRISMA 2020,[25] consistent with previous studies.[26,27] Registered on website Open Science Framework (https://osf.io/e5uxd/).
Focused question
The PICO question was formulated: “What is the effect of gastric juice on the surface, optical and mechanical properties of different types of dental ceramics made using the CAD/CAM system?.” Population: specimens of dental ceramics made by the CAD/CAM system. Intervention: immersion in acid simulating gastric juice. Comparison: without immersion. Outcome: surface, optical, and mechanical properties.
Eligibility
Included studies: in vitro, analyzing the properties of ceramic specimens manufactured by the CAD/CAM method after immersion in acid. Exclusion: ceramics not using the CAD/CAM method and articles without a control group.
Search strategy
PubMed/MEDLINE, EMBASE, Web of Science, Scopus, Cochrane Library, and ProQuest was search to July 2024, without restrictions. Terms are presented in Supplementary Table 1 (available online).
Supplementary Table 1.
Set of terms used in databases
| Database | Lines | Terms |
|---|---|---|
| PubMed/MEDLINE | #1 | ((((((((((“dental ceramics”) OR (“ceramic restorations”)) OR (“CAD/CAM dental ceramic”)) OR (“CAD/CAM restorative materials”)) OR (“CAD-CAM monolithic materials”)) OR (“CAD/CAM ceramic blocks”)) OR (“lithium disilicate”)) OR (“feldspathic”)) OR (“leucite”)) OR (“zirconia”)) OR (“hybrid ceramics”)) OR (“polymer infiltrated ceramic”) |
| #2 | ((((“gastric juice”) OR (“gastric acid”)) OR (“hydrochloric acid”) | |
| #3 | (((((((((((((“physical properties”) OR (“physicochemical properties”)) OR (“roughness”)) OR (“surface roughness”)) OR (“optical properties”)) OR (“optical phenomena”)) OR (“color stainability”)) OR (“color stability”)) OR (“mechanical properties”)) OR (“mechanical stress”)) OR (“flexural strength”)) OR (“fracture toughness”)) OR (“hardness”)) OR (“microhardness”) | |
| #4 | #1 AND #2 AND #3 | |
| EMBASE | #1 | ((((((((((((“dental ceramics”)) OR (“ceramic restorations”)) OR (“CAD/CAM dental ceramic”)) OR (“CAD/CAM restorative materials”)) OR (“CAD-CAM monolithic materials”)) OR (“CAD/CAM ceramic blocks”)) OR (“lithium disilicate”)) OR (“feldspathic”)) OR (“leucite”)) OR (“zirconia”)) OR (“hybrid ceramics”)) OR (“polymer infiltrated ceramic”) |
| #2 | ((((“gastric juice”) OR (“gastric acid”)) OR (“hydrochloric acid”) | |
| #3 | ((((((((((((“Computer-Aided Design”)) OR (“Digital Technology”)) OR (“Digital Technologies”)) OR (“CAD-CAM”)) OR (“Computer-Assisted Design”)) OR (“Computer-Aided Manufacturing”)) OR (“Computer Aided Manufacturing”)) OR (“Computer-Assisted Manufacturing”)) OR (“Computer Assisted Manufacturing”)) OR (“Computer-Aided Manufacture”)) OR (“CAD CAM”)) OR (“Milled Denture”) | |
| #4 | #1 AND #2 AND #3 | |
| Web of Science | #1 | (((((((((((ALL=(“dental ceramics”)) OR ALL=(“ceramic restorations”)) OR ALL=(“CAD/CAM dental ceramic”)) OR ALL=(“CAD/CAM restorative materials”)) OR ALL=(“CAD-CAM monolithic materials”)) OR ALL=(“CAD/CAM ceramic blocks”)) OR ALL=(“lithium disilicate”)) OR ALL=(“feldspathic”)) OR ALL=(“leucite”)) OR ALL=(“zirconia”)) OR ALL=(“hybrid ceramics”)) OR ALL=(“polymer infiltrated ceramic”) |
| #2 | (((ALL=(“gastric juice”) OR ALL=(“gastric acid”)) OR ALL=(“hydrochloric acid”) | |
| #3 | (((((((((((ALL=(“Computer-Aided Design”)) OR ALL=(“Digital Technology”)) OR ALL=(“Digital Technologies”)) OR ALL=(“CAD-CAM”)) OR ALL=(“Computer-Assisted Design”)) OR ALL=(“Computer-Aided Manufacturing”)) OR ALL=(“Computer Aided Manufacturing”)) OR ALL=(“Computer-Assisted Manufacturing”)) OR ALL=(“Computer Assisted Manufacturing”)) OR ALL=(“Computer-Aided Manufacture”)) OR ALL=(“CAD CAM”)) OR ALL=(“Milled Denture”) | |
| #4 | #1 AND #2 AND #3 | |
| Scopus | #1 | TITLE-ABS-KEY (“dental ceramics”) OR TITLE-ABS-KEY (“ceramic restorations”) OR TITLE-ABS-KEY (“CAD/CAM dental ceramic”) OR TITLE-ABS-KEY (“CAD/CAM restorative materials”) OR TITLE-ABS-KEY (“CAD-CAM monolithic materials”) OR TITLE-ABS-KEY (“CAD/CAM ceramic blocks”) OR TITLE-ABS-KEY (“lithium disilicate”) OR TITLE-ABS-KEY (“feldspathic”) OR TITLE-ABS-KEY (“leucite”) OR TITLE-ABS-KEY (“zirconia”) OR TITLE-ABS-KEY (“hybrid ceramics”) OR TITLE-ABS-KEY (“polymer infiltrated ceramic”) |
| #2 | TITLE-ABS-KEY (“gastric juice”) OR TITLE-ABS-KEY (“gastric acid”) OR TITLE-ABS-KEY (“hydrochloric acid”) | |
| #3 | TITLE-ABS-KEY (“physical properties”) OR TITLE-ABS-KEY (“physicochemical properties”) OR TITLE-ABS-KEY (“roughness”) OR TITLE-ABS-KEY (“surface roughness”) OR TITLE-ABS-KEY (“optical properties”) OR TITLE-ABS-KEY (“optical phenomena”) OR TITLE-ABS-KEY (“color stainability”) OR TITLE-ABS-KEY (“color stability”) OR TITLE-ABS-KEY (“mechanical properties”) OR TITLE-ABS-KEY (“mechanical stress”) OR TITLE-ABS-KEY (“flexural strength”) OR TITLE-ABS-KEY (“fracture toughness”) OR TITLE-ABS-KEY (“hardness”) OR TITLE-ABS-KEY (“microhardness”) | |
| #4 | #1 AND #2 AND #3 | |
| Crocrhane Library | #1 | ((((((((((“dental ceramics”) OR (“ceramic restorations”)) OR (“CAD/CAM dental ceramic”)) OR (“CAD/CAM restorative materials”)) OR (“CAD-CAM monolithic materials”)) OR (“CAD/CAM ceramic blocks”)) OR (“lithium disilicate”)) OR (“feldspathic”)) OR (“leucite”)) OR (“zirconia”)) OR (“hybrid ceramics”)) OR (“polymer infiltrated ceramic”) |
| #2 | ((((“gastric juice”) OR (“gastric acid”)) OR (“hydrochloric acid”) | |
| #3 | (((((((((((((“physical properties”) OR (“physicochemical properties”)) OR (“roughness”)) OR (“surface roughness”)) OR (“optical properties”)) OR (“optical phenomena”)) OR (“color stainability”)) OR (“color stability”)) OR (“mechanical properties”)) OR (“mechanical stress”)) OR (“flexural strength”)) OR (“fracture toughness”)) OR (“hardness”)) OR (“microhardness”) | |
| #4 | #1 AND #2 AND #3 | |
| ProQuest | #1 | (((((((((noft= (“dental ceramics”) OR noft= (“ceramic restorations”)) OR noft= (“CAD/CAM dental ceramic”)) OR noft= (“CAD/CAM restorative materials”)) OR noft= (“CAD-CAM monolithic materials”)) OR noft= (“CAD/CAM ceramic blocks”)) OR noft= (“lithium disilicate”)) OR noft= (“feldspathic”)) OR noft= (“leucite”)) OR noft= (“zirconia”)) OR noft= (“hybrid ceramics”)) OR noft= (“polymer infiltrated ceramic”) |
| #2 | (((noft= (“gastric juice”) OR noft= (“gastric acid”)) OR noft= (“hydrochloric acid”) | |
| #3 | ((((((((((((noft= (“physical properties”) OR noft= (“physicochemical properties”)) OR noft= (“roughness”)) OR noft= (“surface roughness”)) OR noft= (“optical properties”)) OR noft= (“optical phenomena”)) OR noft= (“color stainability”)) OR noft= (“color stability”)) OR noft= (“mechanical properties”)) OR noft= (“mechanical stress”)) OR noft= (“flexural strength”)) OR noft= (“fracture toughness”)) OR noft= (“hardness”)) OR noft= (“microhardness”) | |
| #4 | #1 AND #2 AND #3 |
Extracting data
Full text was evaluated for extracting data. The information was classified according to the author, years of studies, number of specimens, types of ceramics, acid immersion method, method evaluated, results, conclusion, and effect of the intervention (acid immersion) (positive/negative/none).
Bibliometric analysis
The quality of the full-text articles was evaluated for Joanna Briggs Institute critical for nonrandomized experimental studies.[28] The following 9 items to be considered.
Meta-analysis
The meta-analysis was the inverse variance method (P < 0.05). The program was used Reviewer Manager 5.4; Cochrane Group.
RESULTS
Search strategy
Through a database search, 264 studies selected: 66 on PubMed/MEDLINE, 53 on EMBASE, 75 on Web of Science, 50 on Scopus, 1 from Cochrane Library, and 19 from ProQuest. Duplicate records being removed; thus 179 articles were selected for the evaluation of titles and abstracts. Seventeen articles were selected for application eligibility. Finally, four articles[29,30,31,32] were excluded [Supplementary Table 2]. The search strategy is shown in Figure 1.
Supplementary Table 2.
Article excluded and reasons for exclusion
| Article excluded | Reasons for exclusion |
|---|---|
| Turp et al.[29] | 1.0 mm thick feldspathic ceramic was applied to the surface of each sample |
| Radwan et al.[30] | Systematic review |
| Reidelbach et al.[32] | 0.113 wt% HCl in deionized water |
| Egilmez et al.[33] | Erosion and abrasion associated with external factors such as a brushing apparatus and a solution of 0.5 vol% citric acid |
Figure 1.
Flowchart detailing the search strategy
Articles characteristics
Fifteen in vitro studies,[2,15,16,17,19,20,21,22,23,33,34,35,36,37] between 2014 and 2022, 777 specimens. were included. Twelve studies[2,15,16,17,19,20,21,33,34,36,37] analyzed roughness, six[2,19,22,33,35] focused on color stability, four[2,16,23,34] on microhardness, and two[19,31] on mechanical resistance. The characteristics of the articles are shown in Table 1.
Table 1.
Characteristics of the included studies
| Author | Number of specimens | Ceramics | Outline | Erosive challenge | Valuation of properties | Results |
Conclusion | Effect | |
|---|---|---|---|---|---|---|---|---|---|
| No acid, mean±SD | With acid, mean±SD | ||||||||
| Harryparsad et al., 2014[15] | 18 | (1) LD (2) LEU (3) Feldspathic |
Erosive and types ceramic | HCl (pH 2) (I) 7.5 h (II) 45 h (III) 91 h in incubator at 37°C |
Roughness Surface | (1) 42.375±9.967 (2) 391.667±86.204 (3) 342.333±136.457 |
(1) I: 94.708±57.938 II: 52.308±37.319 III: 25.133±7.656 (2) I: 268.500±103.119 II: 437.167±194.623 III: 239.750±124.166 (3) I: 488.333±184.096 II: 320.917±76.405 III: 369.817±126.236 |
The erosive test increased the roughness of all ceramics. However, it decreased in 91 h in LD and LEU | Negative |
| Sulaiman et al., 2015[21] | 30 | (1) LD (2) Zirconia |
Erosive and types ceramic | HCl (pH 1.2) 96 h in incubator at 37°C |
Roughness Surface | (1) 0.011±0.002 (2) 0.013±0.002 |
(1) 0.014±0.001 (2) 0.008±0.001 |
The roughness of FSZ and ZEN significantly decreased while lithium disilicate increased after immersion in acid | Positive/negative |
| Backer et al., 2017[16] | 28 | Nanoceramic | Effect of erosive challenge with different pH | HCl (pH 1.2) (1) 6 h (2) 24 h in incubator at 37°C |
(I) Hardness (II) Roughness |
(I) 109.2±5.1 (II) 0.45±0.13 |
(1. I) 110.5±2.8 (1. II) 0.40±0.09 (2. I) 106.3±2.7 (2. II) 0.54±0.14 |
After 6 h showed lower roughness and hardness, but after 24 h decreased | Negative |
| Fathy and Swain, 2018[20] | 25 | Zirconia-reinforced lithium silicate glass ceramic | Effect of erosive challenge at different pH | HCl (1) pH 3 (2) pH 1.2 for (I) 24 h, (II) 168 h |
Roughness surface | 0.357±0.054 | (1. I) 0.375±0.124 (1. II) 0.618±0.117 (2. I) 0.365±0.002 (2. II) 0.474±0.141 |
7 days gave the highest statistically significant results | Negative |
| Egilmez et al., 2018[33] | 144 | Hybrid ceramics (1) Nanoceramic resin (Cerasmart) (2) Nanoceramic resin (Lava Ultimate) (3) Polymer- infiltrated ceramic network (Vita Enamic) |
Effect of erosive in different hybrid ceramics | (HCl pH 1.2) 24 h at 37°C |
I) Flexural strength II) Roughness |
(1. I) 146±15 (2. I) 149±20 (3. I) 124±18 (1. II) 53.18±11.06 (2. II) 74.17±15.44 (3. II) 195.16±63.58 |
(1. I) 147±26 (2. I) 162±25 (3. I) 128±9 (1. II) 44.23±16.19 (2. II) 67.95±12.47 (3. II) 173.20±35.53 |
Exposure to HCl did not change the flexural strength of the materials | Positive/negative |
| Alnasser et al., 2019[14] | 80 | (1) LEU (2) Zirconia (3) LD (4) Feldspathic |
Effect of erosive and different types of ceramics | (HCl 5% pH 2) (I) 45 and (II) 91 h at 37°C |
Roughness surface | (1) 1.23±0.66 (2) 0.54±0.23 (3) 0.13±0.14 (4) 0.61±0.60 |
(1. I) 1.65±0.60 (2. I) 0.51±0.20 (3. I) 0.16±0.20 (4. I) 1.08±0.89 (1. II) 1.95±0.64 (2. II) 0.52±0.19 (3. II) 0.13±0.15 (4. II) 1.15±0.86 |
LEU and feldspathic showed significant static increases in roughness, while LD and zirconia did not show statistically significant differences | Positive/negative |
| Kulkarni et al., 2020[19] | 120 | (1) Feldspathic (2) LD (3) Zirconia |
Erosive n and types ceramic | HCl (pH 2) in 108 h | (I) Color (II) Roughness (III) Mechanical resistance |
(1. I) 58.13±3.04 (2. I) 56.82±1.43 (3. I) 72.21±1.85 (1. II) 0.47±0.25; (2. II) 0.36±0.08; (3. II) 0.19±0.16 (1. III) 120.93±56.93 (2. III) 297.16±51.81 (3. III) 1093.35±139.91 |
(1. I) 58.79±0.97 (2. I) 57.76±1.08 (3. I) 73.40±0.70 (1. II) 1.66±0.83; (2. II) 0.43±0.17; (3. II) 0.39±0.13 (1. III) 125.10±32.55 (2. III) 342.75±64.36 (3. III) 1057.57±165.52 |
The erosive challenge affected the roughness of the three ceramics | Positive/negative |
| Willers et al., 2020[17] | 10 | (1) Zirconia (2) LD |
Effect of erosive and different types of ceramics | (HCl pH 1.2) 30 h at 37°C | Surface roughness | (1) 0.52±0.14 (2) 0.46±0.07 |
(1) 0.60±0.06 (2) 0.44±0.06 |
Monolithic zirconia showed higher roughness values | Negative |
| Cruz et al., 2020[2] | 128 | (1) Nanoceramic resin (2) Polymer-infiltrated ceramic network (3) LD (4) Zirconia reinforced lithium silicate ceramic |
Effect of erosive and different types of ceramics | (HCl pH 1.2) 18 h | (I) roughness (II) hardness (III) Color |
(1. I) 0.74±0.11 (2. I) 0.94±0.08 (3. I) 0.58±0.09 (4. I) 0.59±0.12 (1. II) 100.6±3.6 (2. II) 229.4±37.3 (3. II) 514.5±10.4 (4. II) 580.4±14.0 |
(1. I) 0.49±0.08 (2. I) 0.70±0.11 (3. I) 0.22±0.02 (4. I) 0.23±0.08 (1. II) 99.4±3.6 (2. II) 209.0±9.1 (3. II) 514.3±5.8 (4. II) 572.8±9.8 (1. III) 0.63±0.24 (2. III) 0.57±0.33 (3. III) 0.33±0.19 (4. III) 0.28±0.15 |
Exposure to acid significantly decreases the roughness of ceramics | Negative |
| Farhadi et al., 2021[34] | 16 | (1) Feldspathic (2) LD |
Effect of erosive and different types of ceramics | (HCl pH 2.45) 168 h at 37°C | Surface roughness | (1) 0.03±0.17 (2) 0.13±0.20 |
(1) 0.07±0.22 (2) 0.09±0.18 |
There was no statistically significant difference | Positive |
| Pîrvulescu et al., 2021[35] | 40 | (1) Feldspathic (2) Nanoceramic (3) Polymer-infiltrated ceramic network (4) Leucite-reinforced glass ceramic |
Effect of erosive and different types of ceramics | (HCl pH 1.2) 18 h at 37°C | (I) Surface roughness (II) Translucency parameters |
(1. I) 0.81±0.15 (2. I) 0.89±0.06 (3. I) 0.92±0.07 (4. I) 0.63±0.07 (1. II) 19.51±2.19 (2. II) 24.03±0.98 (3. II) 21.26±3.06 (4. II) 19.56±3.87 |
(1. I) 1.3±0.08 (2. I) 0.92±0.06 (3. I) 0.98±0.08 (4. I) 0.72±0.06 (1. II) 18.43±2.11 (2. II) 24.36±1.25 (3. II) 21.76±2.72 (4. II) 20.74±3.42 |
The difference in feldspathic was statistically significant with higher surface roughness | Negative |
| Raneem et al., 2021[36] | 33 | (1) Monochromatic zirconia (2) Colored-zirconia |
Effect of erosive and different types of ceramics | (HCl pH 1.2) for 2 min, rinsed with water and stored in distilled water for 30 min between acid exposures, repeated 208 times | (I) Color (II) Surface gloss (III) Hardness |
(1. I) 0.12±0.04 (2. I) 0.12±0.06 (1. II) 175.83±7.32 (2. II) 178.39±5.93 (1. III) 1544±3.19 (2. III) 1543.86±2.25 |
(1. I) 2.91±1.72 (2. I) 2.72±1.09 (1. II) 185.21±11.26 (2. II) 183.49±5.2 (1. III) 1474.21±1.53 (2. III) 1473.58±1.62 |
Significant color changes were found in both materials. Surface hardness had a statistically significant reduction | Negative |
| Theocharidou et al., 2022[22] | 20 | (1) Zirconia (2) LD |
Effect of erosive and different types of ceramics | (HCl pH 1.2) 16 h at 37°C | (I) Translucency parameter (II) Color |
(1. I) 3.38±0.74 (2. I) 10.79±1.78 (1.II) 0.96±0.01 (2.II) 0.86±0.02 |
(1. I) 2.56±1.36 (2. I) 4.28±0.92 (1. II) 0.98±0.01 (2. II) 0.94±0.01 |
A decrease in the translucency parameter for LD. Zirconia had a significantly higher contrast | Negative |
| da Cruz et al., 2022[37] | 75 | (1) Nanoceramic resin (2) Polymer-infiltrated ceramic network (3) LEU-reinforced feldspathic porcelain (4) LD (5) Zirconia reinforced lithium silicate ceramic |
Effect of erosive, different types of ceramics, immersed in (a) deionized water, (b) coffee, or (c) cola, and Time in baseline (T0), first (T1), third (T3) and fifth (T5) simulated year of clinical function | HCl pH 1.2 storage in for 3 h immersion | I) Surface roughness II) Color |
(1. I. T0) 0.29±0.07 (2. I. T0) 0.37±0.09 (3. I. T0) 0.18±0.05 (4. I. T0) 0.19±0.03 (5. I. T0) 0.24±0.07 |
(1. I. T1) 0.82±0.18 (2. I. T1) 0.89±0.11 (3. I. T1) 0.19±0.02 (4. I. T1) 0.15±0.02 (5. I. T1) 0.16±0.03 (1. I. T3) 0.90±0.04 (2. I. T3) 1.10±0.10 (3. I. T3) 0.21±0.02 (4. I. T3) 0.14±0.01 (5. I. T3) 0.13±0.01 (1. I. T5) 0.89±0.04 (2. I. T5) 0.19±0.12 (3. I. T5) 0.23±0.02 (4. I. T5) 0.13±0.01 (5. I. ) 0.12±0.01 (1. II. a) 0.26±0.12 (2. II. a) 0.38±0.11 (3. II. a) 0.18±0.08 (4. II. a) 0.42±0.13 (5. II. a) 0.63±0.16 (1. II. b) 1.34±0.14 (2. II. b) 0.56±0.13 (3. II. b) 0.54±0.31 (4. II. b) 0.37±0.09 (5. II. b) 1.81±0.32 (1. II. c) 0.17±0.09 (2. II. c) 0.92±0.25 (3. II. c) 0.84±0.32 (4. II. c) 0.27±0.13 (5. II. c) 0.73±0.10 |
In the 1st year of clinical function (T1), resin nanoceramic and the polymer-infiltrated ceramic network showed an increase in roughness | Positive/negative |
| Kermanshah et al., 2022[23] | 40 | (1) Feldspathic (2) LD |
Effect of erosive immersed in different solutions: (a) saliva (control), (b) acid gastric, (c) sodium fluoride (pH 5.9 for 69 h) + gastric acid and different types of ceramics |
(HCl pH 1.4) 168 h at 37°C | Surface micro-hardness | (1. a) 747.59±20.37 (2. a) 733.78±15.75 (1. b) 689.79±44.48 (2. b) 718.41±34.19 (1. c) 740.30±30.63 (2. c) 744.23.78±18.94 |
(1. b) 606.58±106.09 (2. b) 670.23±24.6 (1. c) 316.00±130.55 (2. c) 598.46±39.57 |
There was a statistically significant decrease in hardness after immersion in (c) sodium fluoride + acetic acid, in both ceramics | Negative |
BRX: Bruxzir Zircoa, KAT: Katana high translucent, FSZ: Fully stabilized zirconia, LEU: Leucita, LD: Dissilicato de lítio, PRT: Prettau zirconia, PSZ: Partially stabilized zirconia, ZEN: Wieland Zenostar translucent, SD: Standard deviation
Types of ceramic
Different types of ceramic blocks for CAD/CAM were used to prepare the specimens: lithium disilicate ceramic was used in nine studies[2,15,14,17,19,22,23,32,35] feldspathic ceramic in seven,[15,14,19,21,23,32,33] leucite in three,[15,33,37] zirconia in three,[14,17,19] partially stabilized zirconia in three,[21,22,36] fully stabilized zirconia in one,[21] zirconium dioxide-reinforced lithium silicate in three,[2,20,37] nanoceramic resin in five,[2,16,33,35,37] and polymer-infiltrated ceramics in four studies.[2,33,35,37]
Erosive challenge
For the erosive challenge, different concentrations and exposure times were used. In 10 studies,[2,16,17,20,21,22,33,35,36,37] HCl of pH 1.2 was used for immersion. In three studies,[15,14,19] pH of 2.0 was used. Kermanshah et al.[23] used a pH of 1.4, Farhadi et al.[34] used a pH of 2.45, and Fathy et al.[20] used a pH of 3.0. The immersion periods were as follows: 3 h,[37] 6 h,[16] 6.93 h,[36] 7.5 h,[15] 16 h,[22] 18 h in 2 articles,[2,35] 24 h in three studies,[16,20,33] 30 h,[17] 45 h in 2 articles,[14,15] 91 h in 2 articles,[14,15] 96 h,[21] 108 h,[19] and 168 h in 2 articles.[23,34]
Risk of bias
Joanna Briggs Institute critical for nonrandomized experimental studies indicated a low risk of bias because all studies met more than 60% of the criteria, which indicates high quality [Table 2].
Table 2.
Critical evaluation results for quasi-experimental studies (nonrandomized experimental studies)
| Estudo | q1 | q2 | q3 | q4 | q5 | q6 | q7 | q8 | q9 | Percentage total |
|---|---|---|---|---|---|---|---|---|---|---|
| Harryparsad et al., 2014 | Y | Y | Y | Y | Y | N/A | Y | U | U | 75 |
| Sulaiman et al., 2015 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Backer et al., 2015 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Kulkarni et al., 2016 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Fathy et al., 2018 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Egilmez et al., 2018 | Y | Y | Y | Y | Y | N/A | Y | U | N | 87.5 |
| Alnasser et al., 2019 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Willers et al., 2020 | Y | Y | Y | Y | U | N/A | Y | Y | Y | 87.5 |
| Cruz et al., 2020 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Farhadi et al., 2021 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Pîrvulescu et al., 2021 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Raneem et al., 2021 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Theocharidu et al., 2022 | Y | Y | Y | Y | Y | N/A | Y | U | Y | 87.5 |
| Da cruz et al., 2022 | Y | Y | Y | Y | Y | N/A | Y | U | Y | 87.5 |
| Kermanshah et al., 2022 | Y | Y | Y | Y | Y | N/A | Y | Y | Y | 100 |
| Percentage total | 100 | 100 | 100 | 100 | 93.33 | 00 | 100 | 73.33 |
N/A: Not available, Y: Yes, U: Unclear
Meta-analysis
Da Cruz et al.[37] was the only one not included in the meta-analysis as it presented a great methodological difference in relation to the other studies, making a comparison impracticable. Therefore, 14 studies were included in the meta-analysis. The surface roughness, color stability, and microhardness tests were considered for the meta-analysis based on the number of studies and possible comparison data, and subgroups were created based on the ceramic type for individual analysis. The diamonds in the meta-analysis forest plot shifted to the lowest values.
In the meta-analysis of surface roughness, feldspathic ceramics, lithium disilicate, leucite, monolithic zirconia, zirconia infiltrated with lithium, nanoceramics, and ceramics infiltrated with polymers were analyzed. No significant difference in the surface roughness after the erosive challenge was observed between the ceramic types (P = 0.59; MD: 0.14; 95% confidence interval [CI]: −0.36–0.64; I2 = 86%, P < 0.01). However, when analyzing the subgroups, feldspathic and leucite ceramics presented significantly lower roughness without the erosive challenge ([P = 0.01; MD: 1.03; 95% CI: 0.21–1.85; I2 = 66%, P < 0.01] and [P = 0.02; MD: 0.73; 95% CI: 0.12–1.35; I2 = 0%, P = 0.83], respectively). This result of the meta-analysis presents reliability, as the studies with both ceramics the value of I2 (heterogeneity) presented low values, presenting 0% in studies with leucite ceramics [Figure 2].
Figure 2.
Florest plot. Result: Surface roughness (with erosive challenge vs without erosive challenge). IV: inverse variance; RE: random effects
During meta-analysis of color stability, feldspathic, lithium disilicate, and monolithic zirconia ceramics were analyzed. Significantly less color change was observed without the erosive challenge (P < 0.05; MD: 1.82; 95% CI: 0.86–2.79; I2 = 81%, P < 0.01), although feldspar and leucite ceramics did not show significant differences ([P = 0.53; MD: 0.28; 95% CI: −0.60–1.16] and [P = 0.19; MD: 2.69; 95% CI: −1.36–6.74; I2 = 93%, P < 0.01], respectively) [Figure 3].
Figure 3.
Florest plot. Result: Color stability (with erosive challenge vs without erosive challenge). IV: inverse variance; RE: random effects
In the meta-analysis of surface microhardness, feldspathic, lithium disilicate, monolithic zirconia, lithium-infiltrated zirconia, nanoceramics, and polymer-infiltrated ceramics were analyzed. Significantly lower microhardness was observed for the groups with the erosive challenge (P = 0.03; MD: −0.95; 95% CI: −1.82–−0.08; I2 = 88%, P < 0.01). Despite this, lithium disilicate ceramics, lithium-reinforced zirconia, and nanoceramics showed no significant decrease ([P = 0.33; MD: −0.74; 95% CI: −2.23–0.76; I2 = 83%, P < 0.01], [P = 0.09; MD: −0.61; 95% CI: −1.32, 0.10], and [P = 0.41; MD: −0.23; 95% CI: −0.79–0.32; I2 = 42%, P = 0.18], respectively) [Figure 4].
Figure 4.
Florest plot. Result: Microhardness (with erosive challenge vs without erosive challenge). IV: inverse variance; RE: random effects
DISCUSSION
This study was conducted to analyze the effect of an erosive challenge on the surface, optical, and mechanical properties of different types of ceramics fabricated using the CAD/CAM method. The results of the meta-analysis indicated that although there was no significant change in the surface roughness, there was a significant change in the color stability and microhardness. Thus, the null hypothesis of this study was partially accepted.
Roughness indicates the presence or absence of irregularities on the material surface and is relevant to the primary microbial adhesion on the ceramic surface. Thus, the higher the roughness value, the greater is the bacterial adhesion.[16] The meta-analysis demonstrated that ceramics generally tend to have lower roughness in the absence of an erosive challenge; however, no significant difference was observed. Despite this, leucite and feldspathic ceramics showed a significant increase in roughness following an erosive challenge. This may attributable to the glass particles present in the matrix, which degrade more rapidly than crystalline grains, resulting in a rougher surface.[21,38,39]
Change in the color of a ceramic prosthesis is considered treatment failure, especially when the esthetic region is involved.[19,36] Koroglu et al.[39] demonstrated that the threshold of chromatic difference for clinical perception is ΔE = 1.30 and for clinical acceptability is ΔE = 2.25. The meta-analysis indicated a significantly greater change in color with the erosive challenge; feldspathic and lithium disilicate ceramics did not show differences, while zirconia ceramic showed a significantly greater change indicative of clinical nonacceptability in the study by Raneem et al.[36] This can be explained by the fact that polycrystalline ceramics are less hydrophilic than glass ceramics and contain larger water molecules or pigments in the areas degraded by the acid, reflecting an irregular and diffuse light pattern.[40]
Microhardness is an important mechanical property of dental restorative materials, because defined as resistance to indentation and determines the wear resistance of the prosthesis.[36] The lower the microhardness, the greater the chances of damage due to mechanical brushing and erosive processes. This leads to increased retention of microorganisms and pigmentation, reducing the longevity of restorations.[36] The meta-analysis showed that exposure to HCl resulted in a significant decrease in the hardness of all ceramics. It is suggested that this decrease in microhardness after immersion in HCl is due to the dissolution of the vitreous matrix of the ceramic and elemental components, such as silica, potassium, and aluminum released by the glass phase.[36,41,42]
The high flexural strength of ceramics determines their ability to resist induced flexural forces, chiefly during mastication, which can cause fracture of the restoration.[19,43,44] Studies indicate that alterations caused by the erosive challenge do not negatively impact the resistance of ceramics,[19,33] suggesting that the deterioration is largely limited to the surface of the ceramic material and does not compromise its resistance.[21] However, only two groups of authors have evaluated the flexural resistance of CAD/CAM ceramics after immersion in HCl;[19,33] thus, further studies are needed to investigate the impact of the erosive challenge on the mechanical strength of these materials.
Different HCl concentrations and exposure times have been used in the studies. Backer et al.[16] simulated 2 and 8 years of exposure of CAD/CAM ceramics to vomit by immersion for 6 and 18 h, respectively. Sulaiman et al.[21] exposed monolithic zirconia to an acid solution for 96 h, simulating more than 10 years of exposure. The ISO 6872 standard, which is used to test the solubility of dental materials, indicates that to simulate 2 years of clinical use, exposure to 4% acetic acid at 80°C for 16 h should be performed.[45] The meta-analysis of these studies indicated that ceramics infiltrated by polymer and nanoceramic resin were immersed for a shorter time as compared to resin-ceramics, suggesting that this material could undergo greater degradation on prolonged immersed. In the studies by Harryparsad et al.[15] and Alnasser et al.,[14] feldspathic ceramics, leucite, and lithium disilicate were exposed to the same immersion protocol, with different roughness outcomes; the different exposure times and acid concentrations did not influence the degradation of ceramics, and the results were influenced by the composition of each material.
The main limitation of this study is that only in vitro studies were included. Although these studies simulated intraoral clinical conditions, the chemical and physical challenges presented by the oral environment are difficult to reproduce under experimental conditions. Although the specimens were stored in distilled water, they should have ideally been stored in saliva with the aim of buffering. The variations in immersion protocols, exposure times, and pH of HCl can cause conflict during interpretation and comparison of the study findings. Therefore, further studies with standardized protocols are necessary to confirm the present findings and to identify the most suitable material for patients with comorbidities that alter the pH of the oral cavity.
CONCLUSIONS
Based on the results of this systematic review of in vitro studies, the following conclusions may be drawn:
Among all ceramic types, feldspathic and leucite ceramics underwent the greatest increase in surface roughness after application of an erosive challenge
Zirconia ceramics showed the greatest change in color after an erosive challenge
Feldspathic, zirconia, and polymer-infiltrated ceramics underwent the greatest decrease in hardness after an erosive challenge
The flexural strength of ceramics was not affected by immersion in HCl.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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