Dental implant-supported restorations have become an established treatment option for replacing missing teeth, offering improved aesthetics, masticatory function, and patient satisfaction.[1] Although the implant-supported crowns have good clinical results, the long-term success of these crowns is not only dependent on osseointegration but also on the maintenance of peri-implant tissue health and the mechanical integrity of the prosthesis.[2] Peri-implant mucositis and peri-implantitis are still crucial biological complications, which may affect the treatment results.[3] The prevalence of peri-implant mucositis and peri-implantitis was 46% and 21% at the patient level, respectively, in a systematic review and meta-analysis of 102 studies and 13,030 patients.[4] The results of this study indicate that peri-implant disease is a significant problem and that certain prosthetic factors may be potentially modifiable in order to assess factors associated with implant health.[4]

Two main methods are available for retaining implant-supported crowns, cementation and screw retention, each with its own specific advantages and disadvantages.[5] Cement-retained restorations offer excellent aesthetics, a flat occlusal surface, and the ability to compensate for implant angulation.[6] However, the remaining subgingival cement could lead to plaque formation, inflammatory response around the implant, and problems removing the prosthesis.[7] In contrast, screw-retained crowns allow for easy retrievability, maintenance, and repair without the complications of exuberant cement.[8] However, screw-retained restorations can also have screw loosening, screw fracture, and access channel complications. Therefore, the selection of the retention mechanism must also depend on the biological and mechanical results and not just the aesthetic or technical simplicity.

Clinical parameters used to assess peri-implant soft-tissue health include the presence of plaque, bleeding on probing, probing pocket depth, and the presence of mucosal inflammation.[9] Historically, concerns have been raised about cement retention because of its association with increased peri-implant disease, but recent evidence failed to consistently find a significant difference between cemented retention systems.[10] A systematic review and meta-analysis of six randomised clinical trials reported no statistically significant difference in peri-implant mucositis between cement-retained and screw-retained prostheses (relative risk [RR] = 1.36; 95% confidence interval [CI]: 0.42–4.38; p = 0.61).[10] Likewise, there was no difference in risk of peri-implantitis between groups (RR = 1.00; 95% CI: 0.23–4.31).[10] These results indicate that other clinical considerations, such as oral hygiene, contours, cement removal, and maintenance, may have an impact on the association between retention type and peri-implant tissue status.

Prosthetic difficulties also play a major role in implant longevity and maintenance demands. Screw loosening, loss of retention, chipped ceramics, cracked crowns, and prosthetic repair/replacement are common technical problems.[11] In 2025, a systematic review and meta-analysis, which incorporated 334 zirconia crowns supported by screws from seven studies, identified a 46% reduced relative risk (RR = 0.54; p = 0.02) of complications of screw-retained zirconia crowns in comparison to cement-retained zirconia crowns.[12] Bleeding on probing and longer-term marginal bone loss, however, were generally similar for the two retention systems[12] The results suggest that less technically demanding retention methods do not necessarily translate into better peri-implant soft-tissue conditions; hence, it is important to consider multiple parameters at the same time, both biological and prosthetic.

Although the most ideal crown retention system has been developed in implant prosthodontics, the choice of the most suitable system is still a clinical dilemma due to the lack of harmony between biological health and prosthetic reliability. The clinical outcomes are reported as mixed in existing systematic reviews, and differences in implant characteristics, restoration design, oral hygiene, and duration of function make interpretation difficult. A detailed soft tissue assessment of PIPs and comparison of prosthetic complications could potentially offer clinical relevance for the specific treatment plan and conservation of the implant in the long term. Hence, the objectives of the present analytical cross-sectional study were to compare the peri-implant soft tissue health and the occurrence and type of implant-related complications between cement-retained implant-supported crowns and screw-retained implant-supported crowns, with a special focus on identifying differences in clinical tissue parameters and on restoration-related complications.

This analytical cross-sectional study was conducted at the Department of Prosthodontics, Ayub college of Dentistry Abbottabad, Mansehra. The study lasted for 6 months from 1 November 2025 to 30 April 2026.

The sample size was estimated using the methodology of OpenEpi version 3.01, under the sample size calculation for cross-sectional studies comparing two independent proportions. The calculation was based on the study by Kraus et al. (2024) that reported biological complication rates of 42.1% for cement-retained restorations and 14.3% for screw-retained restorations.[13] A 95% confidence level, 80% power, and an equal allocation ratio (1:1) were taken into consideration. The minimum sample size was estimated as approximately 94 patients (47 patients per group) using the Fleiss formula with continuity correction. An additional 10% of incomplete or unusable data was allowed, and the target sample size was raised to 106, with 53 patients in each retention group.

Eligible patients presenting during the period of time to the study setting were recruited using a non-probability consecutive sampling technique. The patients were divided into two groups based on the type of implant crown retention. Group A included patients with cement-retained implant-supported crowns, and Group B included the patients with screw-retained implant-supported crowns. Recruitment continued until the desired sample size was obtained in both groups. Only one implant-supported crown per patient was selected to allow independence of observations.

Patients of both genders, aged 18 years and older, who received a single implant-supported crown (held by either cement or screw) were all included. Only patients with implant-supported crowns in place for at least 6 months, with clinically accessible implant restorations for periodontal and prosthetic examination, were included. Patients with complete clinical records of implant placement and prosthetic restoration, including those who gave written informed consent, were included.

Patients with implant bridges, overdentures, multiple-unit fixed prostheses, or restorations with an uncertain retention mechanism were excluded. Patients with uncontrolled systemic diseases having the potential to significantly affect peri-implant healing, such as poorly controlled diabetes mellitus, were excluded. Patients who received peri-implant surgical treatment and/or systemic antibiotics in the last three months were also excluded. Patients who had active untreated periodontal disease, or whose clinical records were incomplete or failed to include a comprehensive peri-implant evaluation, were excluded.

Eligible patients were recruited from the Prosthodontics Department of Ayub college of Dentistry Abbottabad, Mansehra after obtaining all the necessary institutional ethical approval and informed consent. Data were collected on a structured data collection form and included demographic and clinical data. Recorded variables comprised age, gender, smoking situation, oral hygiene practices, and medical history, place of the implant, the time of the prosthetic function, the different types of crown materials and the type of prosthetic retention. The patients were split into two groups, cement-retained group and screw-retained group, depending on the type of restorations. A standardized examination protocol was used for all clinical assessments.

Plaque Index, BOP, PD, and presence of Peri-implant Mucosal Inflammation were used to evaluate peri-implant soft-tissue health. The modified plaque index was used to document plaque accumulation, and bleeding on probing was determined by probing gently around the implant. The implant pocket depth was measured in millimeters with a calibrated periodontal probe at the six sites around the implant: the mesiobuccal, midbuccal, distobuccal, mesiolingual, midlingual and distolingual surfaces. Probing depths were determined at each implant, and the mean probing depths were calculated. For peri-implant mucositis, bleeding on probing or suppuration was diagnosed in the absence of progressive supporting bone loss beyond initial remodelling, and provided sufficient radiographic documentation. Clinically, inflammatory signs were determined and, when available, baseline information was used to confirm the diagnosis of peri-implantitis by the presence of bone loss around the implant. When sufficient baseline data were available, clinical inflammatory signs were used together with the presence of loss of supporting bone to diagnose peri-implantitis, according to established criteria.

Prosthetic complications were assessed by direct clinical examination and a review of the treatment records available. The complications assessed were screw loosening, screw fracture, decementation of the crown, chipping of the ceramics, fracture of the crown, and failure of the prosthesis. The integrity of the margins of the crown was also evaluated, as were the stability of the restoration and condition of the occlusal surfaces. Cement-retained restorations – the presence of clinically detectable residual cement was noted, and screw-retained crowns were assessed for complications related to the screw-access channel. Every complication was recorded as an independent occurrence, and the proportion of patients with at least one complication from the prosthesis was calculated. Data were entered into a structured database after checking for completeness and consistency.

Data were analyzed using the Statistical Package for the Social Sciences (SPSS), version 26.0. The quantitative variables such as age, duration of prosthetic function, probing pocket depth, and plaque index scores were presented as mean ± SD for normally distributed variables and median (IQR) for variables that were not normally distributed. Qualitative variables such as gender, smoking, implant location, bleeding on probing, peri-implant mucositis, peri-implantitis, and individual prosthetic complications were expressed as frequencies and percentages. Normality of quantitative variables was assessed using the Shapiro–Wilk test.

Comparisons between cement-retained and screw-retained crowns were performed using the independent-samples t-test for normally distributed continuous variables and the Mann–Whitney U test for non-normally distributed variables. Associations between retention type and categorical outcomes were evaluated using the chi-square test and Fisher's exact test. Multivariable logistic regression was used to assess the association of retention type with bleeding on probing and overall prosthetic complications after adjustment for relevant potential confounders, including smoking status, oral hygiene, implant location, and duration of prosthetic function. Adjusted odds ratios with 95% confidence intervals were reported. A p-value <0.05 was considered statistically significant.

A total of 106 patients were included in the study dataset, with 53 patients each in the cement-retained and screw-retained groups. There were no significant differences between the two groups with regard to age, gender, smoking status, controlled diabetes, or oral hygiene habits (p > 0.05). (Table 1)

Implant and prosthetic properties were similar between groups with respect to location and distribution (anterior/posterior). The screw-retained group, however, had a significantly longer time for the prosthesis to function (p = 0.008), and zirconia crowns were significantly more common in the cement-retained group (p = 0.040). (Table 2)

The results of the peri-implant soft tissue assessment showed that there was significantly more plaque accumulation, probing pocket depth, and bleeding on probing in the cement-retained group than in the screw-retained group (p < 0.05). The clinical mucosal inflammation was higher in cement-retained restorations, but not statistically significant (p = 0.212). (Table 3)

Peri-implant mucositis was significantly more prevalent in the cement-retained group (p = 0.002), and clinically healthy peri-implant tissues were significantly more frequent in the screw-retained group (p = 0.007). However, the occurrence of peri-implantitis did not differ significantly between the two groups (p = 0.716). (Table 4)

There was no statistically significant difference in the overall frequency of prosthetic complications (p = 0.326), but cement-retained crowns had more complications. The cement-retained group had a significantly higher failure rate (p = 0.003). No statistically significant differences were found for other complications, such as screw loosening, screw fracture, ceramic chipping, crown fracture, and crown-margin defects. (Table 5)

Multivariable logistic regression showed that screw-retained crowns had significantly reduced adjusted odds of bleeding on probing (BOP) compared with cement-retained crowns (OR = 0.30; 95% CI: 0.13–0.70; p = 0.006). While screw retention was also correlated with fewer adjusted odds of overall complications of the prosthesis, this correlation was not statistically significant (p = 0.230). Smoking status, plaque index, position of implants, and the time of prosthetic function were not significant independent predictors in either model (p > 0.05). (Table 6)

Table 1. Demographic, medical, and oral hygiene characteristics

Table 2. Implant and crown characteristics

Table 3. Clinical peri-implant soft-tissue parameters

Table 4. Peri-implant disease status

Table 5. Prosthetic and retention-related complications

Table 6. Multivariable logistic regression for selected outcomes

The present analytical cross-sectional study on 106 patients showed better peri-implant soft tissue parameters for screw-retained implant-supported crowns with no statistically significant differences regarding overall prosthetic complications. Cement-retained crowns exhibited higher amounts of plaque, probing pocket depth, bleeding on probing, and peri-implant mucositis. The results were similar to those of Kraus et al. (2024), which found that the bleeding on probing scores were significantly different between cement-retained and screw-retained restorations at 40 ± 22% and 20 ± 17%, respectively (p = 0.011), in a seven-and-a-half-year consecutive randomized clinical trial.[13] Their longer follow-up, however, was in a randomized design that was not the same as the present cross-sectional assessment.

The greater frequency of peri-implant mucositis observed among cement-retained crowns was also consistent with Tomar et al. (2025), who reported significantly more biological complications in cement-retained restorations than screw-retained restorations after five years (36.8% versus 0%; p = 0.0022).[14] Their study also showed that the complication rate was higher in the cement-retained group. The overall prosthetic complications were not significantly different, but the direction of the present findings was similar.[14] The separation could be due to variations in the restoration process, the length of the follow-up period, and complications incorporated into each analysis.

However, Wolfart et al. (2021) in a 24-month randomized clinical trial (RCT) with 56 implant-supported crowns found no significant differences between cement-retained and screw-retained restorations in terms of biological or technical complications.[15] At 12 months, peri-implant mucositis was seen in 17.9% of all the cement-retained restorations and 14.2% of all the screw-retained restorations. They obtained results similar to those of the present analysis, showing that the overall complications of the prostheses may be similar between retention systems, despite the significant soft tissue differences.[15]

Likewise, the clinical, radiographic, and technical outcomes of five-year follow-up data of cement-retained and screw-retained single-implant restorations based on zirconia were basically similar, as reported by Lamperti et al. (2022).[16] There was no difference between the two groups in the overall technical complication rate (15.4%), and there was relative stability in the peri-implant clinical parameters.[16] These findings confirmed that there was no significant difference in the overall prosthetic complications in the present analysis, but did not support a difference in the peri-implant inflammatory parameters.

The favorable probing pocket depth in cement-retained restorations reported in the present study was supported by the systematic review and meta-analysis conducted by Potdukhe et al. (2024), which found the probing pocket depth in cement-retained restorations was significantly greater at three years (p < 0.05).[17] This difference became non-significant at five years, though. In addition, their review found no substantial differences in MBL among the retention systems, indicating that the differences found for soft-tissue measurements may not reflect differences in supporting bone levels.

A systematic review and meta-analysis of six randomized clinical trials (RCTs) by Dos Reis et al. (2025), however, concluded that there was no difference in the incidence of peri-implant mucositis (RR = 1.36; p = 0.61) or peri-implantitis (RR = 1.00) between different retention systems.[18] The results in the present analysis were similar to the significant mucositis association, but not to the significantly non-differential peri-implantitis. Variations between individual investigations may be due to differences in inclusion/exclusion of patients, diagnostic criteria, or study designs.

Prosthetic problems showed significantly more crown failure due to cement in the present analysis, whereas the other complications, that is, screw loosening, screw fracture, ceramic chipping, and crown fracture, did not differ significantly between the groups. In a meta-analysis of 334 zirconia implant-supported crowns, Tomar et al. (2025) found that screw-retained crowns significantly reduced the overall incidence of complications (RR = 0.54; p = 0.02).[14] This indicated a higher mechanical advantage for screw retention than found in the present analysis, although both studies suggested the pattern of complications could vary depending on the type of retention.

The results were also partially in accordance with Atieh et al. (2025) in a systematic review of 167 nonmolar restorations comparing the angled screw-channel-retained and cement-retained crowns.[19] There were no significant differences in probing depth, technical difficulties, or marginal bone loss between them in their analysis.[19] These conclusions were generally similar, but the authors suggest that screw-retained restorations may have a slight advantage in terms of bleeding on probing. They found, however, that their results confirmed some, not all, of the differences found in the present analysis.

The results were also compared with those of Doolgindachbaporn et al. (2026), who analysed 31 studies and concluded that there was no statistically significant difference in marginal bone changes between the two types of implant crowns (cement-retained vs. screw-retained) (p = 0.888).[20] They also determined that factors linked to changes in the marginal bone were implant location, loading protocol, and cement type. While the present analysis did not quantify the marginal bone loss, these findings pointed to the need to take into account clinical and prosthetic factors other than the type of retention for interpretation of peri-implant outcomes.

Lv et al. (2021) performed a one-year, randomized clinical trial (RCT) to compare angulated screw-retained and cement-retained single-implant crowns (SR-SIC) in the aesthetic region.[21] They investigated the following parameters: probing depth, plaque index, bleeding on probing, marginal bone loss, and peri-implant inflammatory markers.[21] This study provided a relevant comparison because it assessed biological outcomes using several of the same clinical parameters. However, inflammatory biomarkers were not analyzed, so there was a lack of direct comparison of tissue responses.

The published scientific evidence showed conflicting results on the biological and mechanical benefits of the two types of implant-supported crowns (cement-retained and screw-retained). The present analysis revealed that the presence of screws was associated with lower bleeding on probing, as well as lower bleeding on probing after the confounders were adjusted, while the association with overall prosthetic complications was not considered statistically significant after these adjustments. The results must be viewed with some reservation, given the aforementioned differences between the groups, the nonrandomized assignment of retention type and the lack of temporal and causal inferences due to the cross-sectional design. These results alone, therefore, should not be used to draw any conclusions as to the superiority of any one retention system.

LIMITATIONS

There were some limitations in the present study. First, it had a cross-sectional design, which limited the ability to assess the temporal association between peri-implant complications and crown-retention type. Secondly, the results were not generalizable because of the small number of participants and single-center study design. Third, the results of the study may have been affected by differences in oral hygiene habits, different types of crowns, different implant placement, and different lengths of time the prostheses were in place. Further, a lack of longitudinal follow-up made it difficult to assess the rate of development of complications and the long-term survival of the prosthesis. While confounding variables were chosen, residual confounding may have occurred. Extended follow-up and larger multicenter prospective studies are needed to further explore these associations with a standardized clinical assessment.

The study results revealed that the screw-retained implant-supported crowns led to positive outcomes in terms of peri-implant soft-tissue health, which included lower levels of plaque accumulation, probing pocket depth, bleeding on probing, and the presence of peri-implant mucositis, when compared with cement-retained crowns. No statistically significant difference was found, however, in terms of peri-implantitis or in the overall number of prosthetic complications. Cement-retained restorations exhibited more failure due to retention. The results indicated that, in terms of the overall prosthetic outcome, both screw and cement might have some biological benefits. Therefore, the choice of retention should be made based on the patient's individual features, prosthetic requirements, and maintenance requirements.

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