Cement-retained implant restorations, while offering a viable treatment option for edentulous patients, present a significant challenge: the potential for biological complications due to excess cement. Remaining cement can irritate peri-implant tissues, facilitating bacterial adhesion and inflammation, major factors in peri-implant disease. Studies have shown a strong correlation between excess cement and peri-implant disease, with bone loss and other complications more frequent in cement-retained restorations compared to screw-retained ones. The difficulty in completely removing cement excess is exacerbated by factors such as finish line location below the mucosal margin, undercuts, low cement viscosity, and wider implant diameters. The type of cement used might significantly influence the ease of removal. Calcium aluminate glass ionomer cement (CAGIC) possesses a rubber-like consistency during setting, potentially enabling easier removal than traditional cements such as zinc phosphate (ZNPH). CAGIC offers desirable properties like a short setting time, good flowability resulting in a thin film thickness, reduced microleakage, and high compressive strength. This study aimed to compare the amount of remaining cement excess after using CAGIC and ZNPH cements, hypothesizing that CAGIC would result in less remaining excess due to its superior handling properties.

Several studies have highlighted the issues associated with cement excess in implant-supported restorations. Wilson et al. found excess cement in 81% of implants with peri-implant disease, with inflammation resolving after cement removal. Similar findings have been reported by other groups, emphasizing the detrimental effects of residual cement. Challenges in removing excess cement have been linked to various factors, including finish line location, undercuts, and cement viscosity. While previous research has explored these aspects, few studies have directly compared the efficacy of cement removal using different cement types. The properties of CAGIC, such as its rubber-like consistency, suggested a potential advantage over ZNPH in terms of easier removal and reduced residual cement.

Twenty-two identical zirconia crowns were fabricated and cemented onto dental implant abutments. Ten crowns were cemented with CAGIC and ten with ZNPH. A meticulous procedure was followed, including the use of Teflon tape and silicone to protect abutment screws, composite lids to prevent cement leakage, and a standardized cement application technique. A pilot trial determined the optimal cement gap (0.35 µm). After cementation, excess cement was removed using a stainless-steel probe and dental floss, mimicking clinical practice. The specimens were then fixed in six putty molds and photographed under a microscope. Remaining cement excess was quantified using two methods: pixel area calculation using image analysis software and weighing. Statistical analysis using an independent samples t-test was performed to compare the amount of remaining cement excess between the two groups. The level of significance was set at p=0.05.

The results showed a statistically significant difference in the amount of remaining cement excess between the two cement types. ZNPH consistently demonstrated a significantly greater amount of residual cement than CAGIC. This difference was evident in both the pixel area calculation (p=0.002) and the weight measurements (p=0.005). The mean total number of pixels representing remaining cement excess was considerably higher for ZNPH compared to CAGIC. Similarly, the mean weight of remaining cement excess was substantially greater for ZNPH. The distribution of remaining cement also varied between the two cements; ZNPH showed the greatest amount of remaining cement excess mesially, while CAGIC showed the greatest excess distally.

The findings support the hypothesis that CAGIC leaves significantly less remaining cement excess than ZNPH. This difference likely stems from the distinct mechanical properties of the two cements. The shorter setting time and increased hardness of CAGIC facilitated easier removal, while ZNPH's brittle nature resulted in fragmentation during removal. The timing of cement removal, based on the manufacturer's recommendations, differed between the two cements; this difference was accounted for in the methodology. The observation that neither cement was completely removed aligns with previous research highlighting the difficulty of achieving complete cement removal, particularly when the finish line is submucosal. The distribution of residual cement, with more present mesially and distally, may be attributed to the proximity of neighboring teeth and the fit of the gingival mask. The use of both pixel area calculation and weighing provided complementary data, though the weighing method offered a more comprehensive representation of total cement excess, including that remaining in the gingival mask.

This in vitro study demonstrates that the choice of cement significantly impacts the amount of remaining cement excess after cementation of implant-supported zirconia crowns. CAGIC resulted in significantly less residual cement compared to ZNPH, suggesting its potential as a more suitable cement type for reducing the risk of peri-implant complications. Further clinical studies are needed to confirm these findings and evaluate the long-term clinical implications of using CAGIC in cement-retained implant restorations.

This study's limitations include its in vitro design, which may not fully reflect the complexities of the clinical setting. The standardized cement removal technique, while attempting to mimic clinical practice, might not perfectly replicate the variability in clinical operator technique. Furthermore, the gingival mask, while providing a controlled environment, may not precisely represent the complexities of the soft tissue interaction around implants in the oral cavity. The pixel area calculation, although a valuable approach for quantifying remaining cement, might underestimate the total amount of cement excess if some residual cement remained within the gingival mask.