Selection of 1-mm venting or 2.5-mm screw access holes on implant crowns based on cement extrusion and retention capacity

Abstract

Background This in vitro study aimed to provide evidence regarding the selection of hole diameters of implant crowns to reduce excess cement extrusion at the abutment margin, and to examine the maintenance of their retention capacity in anterior and posterior cement-retained implant crowns. Methods Six groups of implant crowns were prepared according to the position of the teeth and the size of their holes as follows: anterior crown without hole (ANH), anterior crown with 1-mm mini venting hole (AMH), anterior crown with 2.5-mm regular screw access hole (ARH), posterior crown without hole (PNH), posterior crown with 1-mm mini venting hole (PMH), and posterior crown with 2.5-mm regular screw access hole (PRH). Temporary cement was used to bond the crowns to the abutments. The mean amount of excess cement extrusion among the different groups at the abutment margin was calculated. Retentive strength under different hole designs was measured as the dislocation force of the crown using a universal testing machine. One-way ANOVA and Welch’s t-test were used to analyze the results. Results The average amounts of extruded excess cement were 18.96 ± 0.64, 1.78 ± 0.41, and 1.30 ± 0.41 mg in the ANH, AMH, and ARH groups, respectively, and 14.87 ± 0.36, 1.51 ± 0.40, and 0.82 ± 0.22 mg in the PNH, PMH, and PRH groups, respectively. The hole opening in the crowns could significantly reduce residual cement regardless of its size (p < 0.001). The mean retentive strengths were 54.16 ± 6.00, 47.63 ± 13.54, and 31.99 ± 7.75 N in the ANH, AMH, and ARH groups, respectively, and 57.84 ± 10.19, 53.22 ± 6.98, and 39.48 ± 5.12 N in the PNH, PMH, and PRH groups, respectively. The retention capacity of the implant crown deteriorated rapidly as the holes on the crown surface enlarged. Conclusions The presence of a hole on the implant crown reduced the amount of excess cement. The retention ability of the implant crowns deteriorated as the size of the hole increased. Considering the esthetic effect of the crown and the possible influence on crown retention, an implant crown with a 1-mm mini venting hole is a better clinical choice than the one with a 2.5-mm regular screw access hole.

Impact of Hole Modification in Cement-Retained Prosthesis on Mechanical Tensile Experiment

“…The presence of a hole on the crown provides a path for cement and air extrusion rather than being only extruded from the margin, and then the cement fluid pressure at the margin of the abutment is reduced when the crown is seated in its position. this explanation is agreed with Zhou, et al 22 Zhou, et al, showed in their studies that vent holes with smaller diameters (1 mm) can also have advantages for cement extrusion reduction without affecting the retention ability compared with crowns having a regular larger hole (2.5 mm). 22 In these moments, due to the extrusion of air, the adhesive is extruded from the adhesive gap (marginal area), resulting in a large amount of overflow of the adhesive and insufficient filling with or without the formation of air trapping and air bubbles formation (in case of the control group).…”

“…this explanation is agreed with Zhou, et al 22 Zhou, et al, showed in their studies that vent holes with smaller diameters (1 mm) can also have advantages for cement extrusion reduction without affecting the retention ability compared with crowns having a regular larger hole (2.5 mm). 22 In these moments, due to the extrusion of air, the adhesive is extruded from the adhesive gap (marginal area), resulting in a large amount of overflow of the adhesive and insufficient filling with or without the formation of air trapping and air bubbles formation (in case of the control group). Also as the same as zirconia, the hybrid ceramic revealed significant disparities in the mean retentive force (N) of the sub-groups of study.…”

Should the vent hole of posterior implant crowns be placed on the lateral surface? An in vitro study of the hydrodynamic feature of cement extrusion and retention ability

“…Studies have shown that vent holes with smaller diameters (1 mm) can also have advantages for cement extrusion reduction without affecting the retention ability compared with crowns having a regular larger hole (2.5 mm) [ 17 ]. Therefore, it is a novel attempt to change the location of the vent hole to the buccal or lingual side of the posterior crown since that design does not pose esthetic risks.…”

“…It has been suggested that the placement of a vent hole on the implant crown could reduce the cement extrusion at the abutment margin without requiring more procedures or expenses. Compared with larger holes of around 2.5 mm in diameter, smaller holes around 1 mm in diameter have a similar performance in reducing the excess cement extrusion at the abutment cervical margin and cause little or no reduction in the retention ability and biomechanical strength of the crown [ 16 , 17 ].…”

Abutment margin levels and residual cement occurrence in cement‐retained implant restorations: An observational study

“…Only the prevalence of the cement remnants was evaluated without quantifying the amount of the cement residues. Furthermore, although screw‐access channels can help reduce the amount of excess cement (Davoudi & Rismanchian, 2019; Zhou et al, 2022), only restorations with a screw‐access opening were included in this study to enable retrieval of the restoration and its examination for the presence of residual cement.…”