Journal of International Oral Health

ORIGINAL RESEARCH
Year
: 2022  |  Volume : 14  |  Issue : 2  |  Page : 118--127

Clinical evaluation of Carbomer compared with high viscosity glass ionomer in restoration of root caries in geriatric patients: A randomized controlled trial


Reham N Mahmoud, Amir H Ibrahim, Amira F ElZoghby, Omar O Shaalan 
 Faculty of Dentistry, Conservative Dentistry Department, Cairo University, Cairo, Egypt

Correspondence Address:
Dr. Reham N Mahmoud
119D 1st Gate Hadayek Al-Ahram, Giza
Egypt

Abstract

Aim: To evaluate the clinical performance of nano-hydroxyapatite reinforced glass ionomer (Carbomer) vs. conventional high viscosity glass-ionomer cement (Fuji IX) in root caries of geriatric patients. Materials and Methods: The current trial is a randomized controlled trial, with two parallel groups and a 1:1 allocation ratio. A total of 22 participants were recruited using convenience sampling and received 44 restorations randomly using either Carbomer or Fuji IX. After cavity preparation, restorative materials were applied according to manufacturers’ instructions. Restorations were evaluated using modified United States Public Health Service criteria by two blinded assessors after 1, 3, 6, and 9 months and 1 year. The χ2 test was used to associate between the type of restorative material, either Carbomer or Fuji IX, and clinical performance. A P-value ≤ 0.05 was considered statistically significant. Results: After 1 year, no statistically significant difference was found between both materials for marginal staining, surface texture, marginal adaptation, secondary caries, post-operative sensitivity, color match, and retention (P = 0.4885, P = 0.1320, P = 0.3483, P = 0.9170, P = 0.7518, P = 0.1043, and P = 0.2998, respectively), whereas there was statistically significant difference between both materials for anatomical contour after 12 months (P = 0.0477). Conclusion: Both Carbomer™ and Fuji IX showed similar and successful clinical performance in the purpose of restoring root surface of permanent teeth in geriatric patients.



How to cite this article:
Mahmoud RN, Ibrahim AH, ElZoghby AF, Shaalan OO. Clinical evaluation of Carbomer compared with high viscosity glass ionomer in restoration of root caries in geriatric patients: A randomized controlled trial.J Int Oral Health 2022;14:118-127


How to cite this URL:
Mahmoud RN, Ibrahim AH, ElZoghby AF, Shaalan OO. Clinical evaluation of Carbomer compared with high viscosity glass ionomer in restoration of root caries in geriatric patients: A randomized controlled trial. J Int Oral Health [serial online] 2022 [cited 2022 May 21 ];14:118-127
Available from: https://www.jioh.org/text.asp?2022/15/2/118/344066


Full Text

 Introduction



The world’s population is aging rapidly, with associated reduction in levels of edentulism in developed countries. Accordingly, it is expected that there will be a rise in the incidence of root caries due to the increased number of exposed root surfaces.[1] Root caries is a multifactorial, advanced lesion that shows softened, irregular tissue with less resistance to acid violence.[2] Root caries arises on the radicular surface and encompasses cementum, dentin, or enamel in the vicinity of the cemento-enamel junction with an initial presence on the root surface.[3]

Root lesions are often very difficult to restore due to their location, problems with moisture control, and proximity to the pulp and are prone to high rates of recurrent caries; its management considerations vary depending on the extent and location of the lesion, as well as the type of materials being used.[4] Failure rates were high regardless of any restorative materials used for this indication, and at present, there is no “gold-standard” material.[1]

Traditional glass-ionomer cements (GICs) have the desirable properties of biocompatibility and chemical bonding to enamel and dentin. Moreover, GICs have anticariogenic properties which can affect the natural demineralization/remineralization procedure of teeth by the development of fluorapatite (Fap) instead of hydroxyapatite (Hap).[5],[6] However, these materials have the disadvantages of poor esthetics and mechanical properties through time.[7]

GICs have gone through numerous modifications to make it more suitable for clinical application with advanced physical and mechanical characteristics. Highly viscous GICs with higher powder-to-liquid ratio received a lot of attention, which could be packed and expose improved flexural strength characteristics.[8] Fuji IX was released in the mid-90s as a packable or highly viscous GIC. Highly viscous GIC has higher strength, superior wear resistance, and flexural strength than conventional one. In addition, they are less susceptible to moisture and leach more fluorides.[9]

Nanotechnology had significant improvements in the dental field which had been used to upgrade glass-ionomer filling material to a one called glass Carbomer (GC), which has been presented aiming to enhance the physical characteristics of GICs.[10],[11]

GCs are GICs, which have added nanosized Fap and Hap to their composition. They are commercialized as GCP Glass Fill, with very specific advise to be thermo-cured in order to improve the mechanical properties.[5]

There is a lack of data regarding the performance of different restorative materials for the restoration of root carious lesions (RCLs).[1] Therefore, it was found beneficial to evaluate the clinical performance of nano-Hap reinforced glass ionomer (Carbomer) vs. conventional high viscosity GIC (Fuji IX) in root caries of geriatric patients. The null hypothesis tested was that GC would have similar clinical performance to conventional high viscosity glass ionomer in restoring root caries in geriatric patients.

 Materials and Methods



Study settings

The protocol of the current study was registered in www.clinicaltrials.gov (NCT04701320). All procedures held in this study were in accordance with Declaration of Helsinki and the ethical criteria of Research Ethics Committee of Faculty of Dentistry, Cairo University (CREC) (Ref. 19/3/7) at 26th of March 2019.

This is a randomized controlled clinical trial, with two parallel groups (1:1 allocation ratio). Patients were enrolled from outpatient clinic of Conservative Dentistry Department at Faculty of Dentistry, Cairo University, Cairo, Egypt. The selection criteria for the recruitment of participants were patients with age range ≥ 50 years, understand the procedures and able to give own consent, gingival recession and at least one tooth with root caries and no signs or symptoms of irreversible pulpitis, mobility grade ≤ 1, and plaque index ≤ 2. However, patients younger than 50 years old, uncooperative with disabilities, systemic diseases, severe bruxism, clenching or temporomandibular joint problems, teeth with signs of pulpal or periodontal pathology, and possible prosthodontic restoration within 1 year were excluded.

Sample size calculation

According to the results of Nassar et al. in 2014[12] in which the probability of A for conventional nano-glass ionomer (comparator) was (0.769), probability of score B was (0.231) with effect size w = 0.538 (n = 28). If the estimated probability of nano-Hap GC for marginal discoloration was (0.9) for score A, the probability was (0.1) for score B with effect size w = 0.8 (n = 13). By adopting an alpha (α) level of 0.05 (5%), power=80%. The predicted sample size (n) was 41. Sample size was increased by 5% to account for possible dropouts during follow-up intervals to be a total of 44 cases, i.e., 22 for each group. G*Power 3.1.9.2 was used to perform sample size calculation.

Sequence generation, allocation concealment, and blinding

A total of 22 participants were enrolled in the current study which involves restoring 44 lesions. Simple randomization was done by creating numbers from 1:22 via random sequence generator (Randomness and Integrity Services Ltd). The participants and assessors were blinded to the material assignment, whereas the operator was not due to the difference in restorative material presentation and its application protocol.

Restorative procedures

Conservative root cavity was prepared with high-speed handpiece, air and water coolant, and round diamond burs of different diameters. Sharp excavators were used to remove the soft carious lesions. The prepared cavity was cleaned and dried gently with blown air or blotted with cotton pellets. Moisture control is achieved by cotton roll, retraction cord, and saliva ejector. The cavity was cleaned, water-rinsed, and all materials were applied according to manufacturer’s instructions [Table 1].{Table 1}

Assessment of restorations

Modified United States Public Health Service (USPHS) criteria for dental restorations were used to evaluate the restorations by two blinded assessors at baseline, 1, 3, 6, and 12 months [Table 2].{Table 2}

Statistical analysis

Statistical analysis was performed with MedCalc software (MedCalc Software Bvba) version 19 for Windows. Data were represented as frequency and percentage. The χ2 test was used to associate between the type of restorative material, either Carbomer and Fuji IX, and clinical performance followed by multiple regression analysis. Clinical significance was assessed using relative risk. A P-value ≤ 0.05 was considered statistically significant.

 Results



A total of 44 restorations were placed in the current clinical trial of 22 patients with mean age of 55 ± 5 years. After 6 months, there were four restoration losses: one in the Carbomer group and three in Fuji IX group. At the end of 12 months of follow-up, 40 restorations were evaluated with 91% overall retention rate. After 12 months, there was no statistically significant difference between both materials for marginal staining, surface texture, marginal adaptation, secondary caries, post-operative sensitivity, color match, and retention (P = 0.4885, P = 0.1320, P = 0.3483, P = 0.9170, P = 0.7518, P = 0.1043, and P = 0.2998, respectively), whereas there was statistically significant difference between both materials for anatomical contour after 12 months (P = 0.0477).

For marginal staining, intergroup comparison between both materials has shown no statistically significant difference in different follow-up periods: baseline, 1, 3, 6, and 12 months, respectively (P = 1.0000, P = 1.0000, P = 1.0000, P = 0.3300, and P = 0.4885). Intragroup comparison within Carbomer has shown statistically significant difference between different follow-up periods (P < 0.0001), and intragroup comparison within Fuji IX has shown statistically significant difference between different follow-up periods (P < 0.0001).

Regarding surface texture, intergroup comparison between both materials has shown no statistically significant difference within different follow up periods: baseline, 1, 3, 6, and 12 months, respectively (P = 1.0000, P = 1.0000, P = 1.0000, P = 0.2931, and P = 0.1320). Intragroup comparison within Carbomer has shown no statistically significant difference between different follow-up periods (P = 0.9996), and intragroup comparison within Fuji IX has shown no statistically significant difference between different follow-up periods (P = 0.1775).

Concerning anatomical contour, intergroup comparison between both materials has shown no statistically significant difference within different follow-up periods: baseline, 1, 3, and 6 months, respectively (P = 1.0000, P = 1.0000, P = 1.0000, and P = 0.0908), whereas there was a statistically significant difference at 12 months of follow-up (P = 0.0477). Intragroup comparison within Carbomer has shown statistically significant difference between different follow-up periods (P = 0.0162), and intragroup comparison within Fuji IX has shown no statistically significant difference between different follow-up periods (P = 0.9716).

For marginal adaptation, intergroup comparison between both materials has shown no statistically significant difference within different follow-up periods: baseline, 1, 3, 6, and 12 months, respectively (P = 1.0000, P = 1.0000, P = 1.0000, P = 0.7230, and P = 0.3483). Intragroup comparison within Carbomer has shown statistically significant difference between different follow-up periods (P = 0.0407), and intragroup comparison within Fuji IX has shown statistically significant difference between different follow-up periods (P = 0.0021).

For secondary caries, intergroup comparison between both materials has shown no statistically significant difference within different follow-up periods: baseline, 1, 3, 6, and 12 months, respectively (P = 1.0000, P = 1.0000, P = 1.0000, P = 0.7518, and P = 0.9170). Intragroup comparison within Carbomer has shown no statistically significant difference between different follow-up periods (P = 0.0767), and intragroup comparison within Fuji IX has shown no statistically significant difference between different follow-up periods (P = 0.0581).

Concerning post-operative hypersensitivity, intergroup comparison between both materials has shown no statistically significant difference within different follow-up periods: baseline, 1, 3, 6, and 12 months, respectively (P = 1.0000, P = 1.0000, P = 1.0000, P = 0.7518, and P = 0.7518). Intragroup comparison within Carbomer has shown no statistically significant difference between different follow-up periods (P = 0.9996), and intragroup comparison within Fuji IX has shown no statistically significant difference between different follow-up periods (P = 0.9716).

For color match, intergroup comparison between both materials has shown statistically significant difference within different follow-up periods: baseline, 1 and 3 months, respectively (P = 0.0381, P = 0.0381, P = 0.0447), whereas there was no statistically significant difference at 6- and 12-month follow-up periods (P = 0.0520 and P = 0.1043, respectively). Intragroup comparison within Carbomer has shown no statistically significant difference between different follow-up periods (P = 0.1492), and intragroup comparison within Fuji IX has shown no statistically significant difference between different follow-up periods (P = 0.2138).

Finally, for retention, intergroup comparison between both materials has shown no statistically significant difference within different follow-up periods: baseline, 1, 3, 6, and 12 months, respectively (P = 1.0000, P = 1.0000, P = 1.0000, P = 0. 2998, and P = 0. 2998). Intragroup comparison within Carbomer has shown no statistically significant difference between different follow-up periods (P = 0.5486), and intragroup comparison within Fuji IX has shown statistically significant difference between different follow-up periods (P = 0.0494). [Table 3] shows the frequency and percentage of outcomes evaluated using modified USPHS criteria at different follow-up periods between Carbomer and Fuji IX.{Table 3}

 Discussion



Clinical studies are the last and the most important way for evaluating new materials: the most evidenced method to ensure the efficiency of dental materials in clinical practice.[11],[13],[14] Randomized controlled trials (RCTs) are considered to be the decisive final level of evidence that could be applied to assess new materials and techniques and to implement evidence-based guidelines for different clinical situations.[8],[11]

This study represents one of the clinical studies that enrolled independently living older adults lacking a history of oral cancer and radiotherapy.

Root caries is not a “recent” disorder but has been increasing in occurrence due to people living longer and conserving their natural teeth into old age. The gingival recession is greatly involved in the occurrence of root surface caries. It may appear as white or discolored brown or black areas of irregular outline, with or without a cavity at an exposed root surface.[7] The prevalence of root caries in older adults is high; recent surveys have reported that around half of community-dwelling older adults had root caries’ experience.[15] There are three peaks of caries activity, which were identified at 6, 25, and 70 years of age. The peak at age 70 was related to the presence of root/cementum caries.[16]

Management of RCL with restorative materials can be time-consuming and intractable because of the associated problems, such as difficulty in moisture control, poor marginal adaptation, and proximity to the pulp, which can lead to leakage, new carious lesions at the restorative margins, and finally restoration replacement or tooth failure. Hence, there is an urgent need to advance restorative materials and procedures.[17] As coating root surfaces with adhesive materials has been regarded as a promising procedure to prevent demineralization, GIC seems particularly suitable for restoring RCL. The major advantage of GIC is its ability to chemically bond to tooth structure, acting as a F- reservoir in the oral cavity and providing acceptable aesthetic qualities and biocompatibility. It was shown to confer a preventive effect against cariogenic challenge by a mixed-species oral biofilm in an artificial mouth culture system.[17]

GC cement (GCP Dental, The Netherlands) is one of the materials that has been developed as a result of studies on the improvement of GICs. In the development of this material, it is aimed to create an enamel-like structure using nanoparticle technology as it was known that the addition of nano-Hap and nano-Fap could increase the mechanical properties of glass ionomers and their bond strength to dentin. Furthermore, a smooth and polished surface has been obtained as a result of the fine structure of the cement.[18]

GC is used together with an organic, biocompatible surface coating polish (GCP Gloss, GCP Dental) that is carbon-silicone-based, and it enhances restoration’s transparency. It also protects the restoration during the initial setting phase from moisture and salivary contamination and from dehydration afterwards. Furthermore, the monomer-free condition and the addition of nano-sized Hap and Fap particles in GC provide a more biocompatible material than resin-modified glass ionomer.[18],[19]

Manufacturers have recommended that the wear resistance and compressive strength of the material are increased through the use of a light device with a high light power during the hardening process of GC. There is a limited number of studies investigating its clinical performance and remineralizing properties.[18],[19] Moreover, the results of studies evaluating the clinical success of this material have not been clear when used as a permanent restorative material in adult individuals. So, it is seemed that the bioactive GCP Glass Fill might be an additive exciting reference material for further clinical bioactivity studies.[5]

Therefore, this randomized controlled clinical trial aimed to compare the clinical performance of GC with conventional GIC in geriatric patients as a permanent restorative material for RCLs. Fuji IX was chosen to be the reference material as it is found to be the most clinically tested material in both in-vivo and in-vitro studies.[9] Resin composite could not be used as a control in this study as many root caries lesions extend subgingivally, and isolation would not have been applicable to allow predictable dentine bonding. Also, it is previously shown that both of these materials have comparable survival rates in root caries lesions.[1],[20],[21]

According to the manufacturer, GC sets chemically and is optimized for heat curing. An advantage of GC is that it is moisture-tolerant especially in situations in which moisture control can be a challenge.[22] The isolation of the field and moisture control was achieved with the use of cotton rolls and saliva ejector.[1] Water is the third essential component of the GIC beside powder and acid, as a result GIC is sensitive to both moisture and dehydration. It was recommended to leave the cavity moist during the placement of GIC, as the restoration absorbs water during the setting reaction. In case of over dryness of the cavity, glass ionomer absorbs fluid from within the dentinal tubules resulting in post-operative hypersensitivity.[8]

Moreover, the use of cotton rolls/retraction cord was found to be as effective as rubber dam isolation to restore cervical lesions. In addition, patients’ preference, gingival damage, or chairside time was the same for both isolation procedures.[23],[24] These results were in contrary to studies of Bonsor and Pearson[25] who stated that the rubber dam is the most effective and predictable method of achieving moisture control and its use is strongly recommended. However, rubber dam placement might be annoying for geriatric patients and not preferred at all.[26]

All restorations were coated with a varnish (G-coat plus; GC Corporation) for Fuji IX[1],[9] and Carbomer gloss for Carbomer as manufacturer’s instructions.[18] Resin coating of the restorations improved the mechanical properties. It is believed that resin infiltration into the glass ionomer surface fills the surface’s cracks and porosities.[8]

Carbomer restorations were cured for 60 s using the high-energy lamp (thermo-cure). The beneficial effects of heat on glass ionomers have been documented in recent studies.[27],[28] Higher temperatures during setting have been found to shorten the setting and working times.[29]

In the current trial, after 1 year, all patients attended the follow-up with 100% retention rate; thus, the desired sample size was achieved. Previous studies have reported up to 48% drop-out rates after 1 year when treating senior adults.[21]

Twenty-two patients received 44 restorations with a mean age of 62.5 ± 12.5 years. After 6 months, there was a total of four restoration failures: one in the Carbomer group and three in the Fuji IX group; failure defined as restoration loss, restoration fracture with exposure of dentin base, secondary caries with restoration replacement, pain from the restoration, or tooth fracture. At the end of 12 months of follow-up, 40 restorations were evaluated with 91% overall success rate.

After 12 months regarding marginal staining, surface texture, marginal adaptation, secondary caries, post-operative sensitivity, color match, and retention, there was no statistically significant difference between both the materials (P = 0.4885, P = 0.1320, P = 0.3483, P = 0.9170, P = 0.7518, P = 0.1043, and P = 0.2998, respectively), whereas there was statistically significant difference between both materials for anatomical contour after 12 months (P = 0.0477).

For marginal staining, no statistically significant difference was found within different follow-up periods between both tested materials. There was statistically significant difference within the Carbomer group between different follow-up periods (P < 0.0001) and within the Fuji IX group between different follow-up periods (P < 0.0001).

Marginal staining was observed in a small number of cases through the 1-year period. This is may be perhaps due to the glass ionomers’ self-adhesion to tooth structures without the need of adhesive systems.[14]

Regarding surface texture, no statistically significant difference was found between both materials at different follow-up periods. The applied surface coatings have found to seal 35–40 µm of the restorations thickness, protected its margins, and produced a homogeneous and glossy surface. However, they wiped out almost in all cases at the 6-month follow-up, leaving to some extent rougher surface than the corresponding normal enamel. With time, these coatings were wiped out by oral mastication wear, but during this time, the cements are estimated to resist the variations in water balance more and fully mature with maximum mechanical strength that may explain sustained surface texture during the follow-up period (1 year).[14] Carbomer had less mean surface roughness in another study, and they attributed this to the particle size of the material, as it has nanoparticle glass enriched with fluor/Hap which enhances its surface texture.[30] Also it was found that GC cements had high microhardness which attain their surface texture with little changes within the follow-up period.[31]

Concerning anatomical contour, there was no statistically significant difference within different follow-up periods (baseline, 1, 3, 6 months) between both tested materials, whereas there was a statistically significant difference at 12-months follow-up (P = 0.0477). A statistically significant difference was found in the Carbomer group within different follow-up periods (P = 0.0162), whereas in the Fuji IX group there was no statistically significant difference within different follow-up periods (P = 0.9716). The anatomical form loss of the restorations is considered as an indication of oral wear feature and morphological changes.[14] The consistency of GIC is more liquid than the composite, making it difficult to give a natural anatomical form. However, no significant difference was observed in this study along the follow-up period except after 1 year.

For marginal adaptation, there was no statistically significant difference within different follow-up periods between both the tested materials. A statistically significant difference in the Carbomer and Fuji IX groups was found within different follow-up periods (P = 0.0407 and P = 0.0021), respectively. There is a lower percentage of bravo score observed at 1-year follow-up (13% and 22% for Carbomer and Fuji IX, respectively) in terms of marginal adaptation, which is considered as successful restorations. This is probably due to the glass ionomer’s self-adhesion nature to tooth tissues with no need for an adhesive system.[14] Unlike the results of the current study, Carbomer showed lower values regarding its marginal adaptation when compared with composite restoration; this might be due to the fact that GC does not suffer from polymerization like that for the composite resins.[18]

Similar to the current trial, it was found that coated heat-cured GC exhibited lower values of microleakage in comparison to fast setting uncoated GIC and no statistically significant difference between it and the coated GIC.[32],[33]

For secondary caries, there was no statistically significant difference within different follow-up periods between both the tested materials. There was no statistically significant difference within the Carbomer group (P = 0.0767) and Fuji IX group (P = 0.0581). In this study, no significant difference was found between the restorative materials in terms of secondary caries formation. This may be due to the limited 12-months clinical follow-up period. Moreover, the presence of silicate and fluoride in the content of GC may be one of the factors preventing secondary caries formation.[18] The anti-cariogenic effect and fluoride release of the GICs may be a cause of caries inhibition in GICs up to 6 years of follow-up period.[14] Chen et al.[34] found that GCs had lower caries preventive effect in vivo than the high viscosity GICs.

Concerning post-operative hypersensitivity, there was no statistically significant difference within different follow-up periods between both the tested materials and within each tested group (P = 0.9996) for Carbomer and (P = 0.9716) for Fuji IX. During the application stages of GC and Fuji IX, no conditioning process and no additional bonding agent are required. These may be effective and have contributed to the prevention of sensitivity problems due to the biocompatibility of glass ionomer and its anti-cariogenic potential.[8],[18]

GC contains Fap, which has remineralizing action and protects the pulp from thermal damages. The heat application and temperature increasing are below the critical values and are harmless for the pulp.[29],[35] These results were not the same as for Botsali et al.,[36] who found that a pulpal damage may occur with a dentinal depth less than 1 mm.

For color match, there was a statistically significant difference between both materials at different follow-up periods at baseline and 1 and 3 months (P = 0.0381, P = 0.0381, P = 0.0447, respectively), whereas at 6 and 12 months follow-up periods, there was no statistically significant difference (P = 0.0520 and P = 0.1043, respectively). In clinical practice, some reinforced and recent GICs exhibited an enhanced color match with adjacent tooth structures, partially due to the small glass particle inclusions and filled resin-based coating materials.[14] In the current clinical study, it was observed that, alpha scores for color match for both materials increased after 3 months (13.6% for Carbomer and 40.9% for Fuji IX), this may be due to improvement in the translucency of GICs over time as the cements mature.[14] The current results were in agreement with those of Balkaya and Arslan.[37]

Regarding conventional glass ionomer, the current trial results found that no statistically significant difference existed between the baseline and 1 year. However, since the restorations were not in the aesthetic area, and the patients were not bothered by the restoration’s appearance, the restoration’s replacement was not considered to manage the color mismatch. In this study, Fuji IX color match was found to be three times better than that of Carbomer after 3 months, which is different from the findings of Kaynar and Dönme.[18] Concerning the nanohybrid materials, the color match was not ideal, which was not surprising due to the generally accepted suboptimal appearance characteristics and opacity of GICs.[38]

Finally, regarding the retention rate character, partial loss and total loss of the restorations were both measured as failure. There was no statistically significant difference between both the tested materials and within the Carbomer group at different follow-up periods, whereas for Fuji IX there was a statistically significant difference between different follow-up periods (P = 0.0494).

There was an increase in the 12th month Charlie score (13.6% for Fuji IX group and 4.5% only for Carbomer group) compared with that of 1st month. These findings were not similar to the findings reported by Olegário et al.,[13] and this may be attributed to the difference in the population and methodology. They suggested that the decreased retention after 1 year was related to the chemical reaction of Hap during the solidification process.[39] HAp was partially consumed during this stage. Thus, they hypothesized that the consumed apatite in Carbomer could be associated with the carboxylic groups’ interactions, decreasing the available ions to bond with mineral content of teeth, lowering the bond strength. Another explanation is that internal cracks are created during the setting of the material,[33] and it is hypothesized that those cracks could be distributed leading to a low fracture resistance of the material, leading to the restoration breakdown. It was found that even after light curing the material for 60 s, Carbomer still shows a soft consistency. In fact, the same was observed in a laboratory study, in which not all Carbomer restorations were completely hardened, some not even after 40 h. According to the authors, this phenomenon could result in a greater risk of restoration failure.[13]

In contrast to the current trial results, it was found that Fuji IX GP had higher mean shear bond strength (SBS) to the dentinal tissue when compared with GC with statistical significance difference (P = 0.000).[9] They attributed such difference in SBS in the two groups to the dentin pre-conditioning step (not applied in the current trial), which was applied in Fuji IX GP and not in the Carbomer group, which may had affected their results.

At the end of the study, there were no differences between both materials in terms of marginal discoloration, marginal adaptation, surface texture, recurrent caries, post-operative sensitivity, and retention; therefore, the null hypothesis could not be rejected regarding these outcomes. Only differences were found in the anatomic form after 1 year and in the color match at baseline, 1 month, and 3 months. Therefore, the null hypothesis was rejected for these two outcomes.

GC is a newly introduced material which has not yet been approved for clinical use, and our clinical trial suggested its clinical usefulness in the dental field as an effective and successful restorative material. In contrast, it should be used as a permanent restoration under certain conditions and in a specific cavity design which limits its clinical usage. So, randomized clinical trials could be recommended for Carbomer with longer follow-up periods to confirm the current results and to monitor the clinical performance over a longer period of clinical service. Clinical trials’ testing performance of nano-hybrid glass ionomer in other clinical indications are encouraged, to recommend utilizing the new material in various clinical applications.

 Conclusions



Under the limitations of the current investigation, we can conclude the following.

Root caries in geriatric patients could be restored by either Carbomer or Fujiix with the same successful clinical performance.

The new Carbomer material could be beneficial as an effective permanent restorative material in specific cavity designs in geriatric patients.

Clinical recommendations

Randomized clinical trials evaluating Carbomer with longer follow-up periods are advised to confirm the current results and to monitor the clinical performance over a longer period of clinical service.

Clinical trials testing performance of nano-hybrid glass ionomer in other clinical indications is encouraged, to recommend utilizing the new material in various clinical applications.

Acknowledgements

Nil.

Financial support and sponsorship

This study was self-funded by the authors.

Conflicts of interest

The authors declare that there are no conflicts of interest.

Authors’ contribution

RNM: Concepts, design, definition of intellectual content, literature search, clinical studies, operator, data acquisition, and article preparation. AFE and AHI: Concepts, design, definition of intellectual content, auditing and article preparation, editing, and review. OOS: Concepts, design, definition of intellectual content, auditing, data acquisition, data analysis, sample size calculation, statistical analysis and article preparation, editing, and review. Finally, all authors had given approval for publication.

Ethical policy and Institutional Review Board statement

The protocol of this study was registered in www.clinicaltrials.gov/database, with unique identification number NCT04701320. All procedures were in accordance with the ethical standards of the Research Ethics Committee (CREC) of the Faculty of Dentistry, Cairo University with approval number (Ref. 19/3/7).

Patient declaration of consent

The authors had obtained all appropriate patient consent forms. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. This randomized controlled clinical study was held in the Faculty of Dentistry, Cairo University, Cairo, Egypt.

Data availability statement

Data are available on reasonable request.

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