# Clinical performance and occlusal wear of polymer-infiltrated ceramic network and zirconia-reinforced ceramic implant-supported single crowns fabricated via a digital workflow on two titanium implant systems: a 12-month prospective randomized trial

## TL;DR

A study compared two types of dental crowns made from different materials and found that one had better survival and less wear after one year.

## Contribution

The study provides new clinical evidence on the performance of PICN and ZLS crowns in implant dentistry using a digital workflow.

## Key findings

- Zirconia-reinforced lithium silicate (ZLS) crowns had a 100% survival rate, while polymer-infiltrated ceramic network (PICN) crowns had 84%.
- Occlusal wear was significantly higher for PICN (0.45 mm) compared to ZLS (0.16 mm).
- Technical complications occurred in 15% of PICN and 15% of ZLS crowns, with no significant difference between materials.

## Abstract

Polymer-infiltrated ceramic network (PICN) and zirconia-reinforced lithium silicate (ZLS) ceramics are alternatives for implant-supported single crowns (ISCs). This prospective randomized trial evaluated 12-month survival of PICN- and ZLS-ISCs supported by Straumann Bone Level Tapered (BLT) and CAMLOG Promote plus (PP) titanium implants. Furthermore, technical complications and occlusal wear were analyzed.

Sixty-one patients received a single titanium implant from two different manufacturers, and one was treated with two implants. All implants were placed using fully guided static computer-assisted surgery. After randomization, screw-retained CAD-CAM ISCs were fabricated from PICN (n = 31) or ZLS (n = 31) and cemented onto stock titanium base abutments. After 1 year, implant and prosthetic survival, material- and system-dependent outcomes, technical complications, and occlusal wear—based on superimposed baseline and follow-up intraoral scans—were recorded. Independent t-tests were performed (p = 0.05).

Forty-two ISCs were evaluated after one year (mean follow-up: 409.5 ± 102.6 days). PICN showed a 84% survival rate, while ZLS achieved 100% survival. Debonding occurred in five restorations (PICN = 2; ZLS = 3). No complications were observed in 86% of PICN and 85% of ZLS crowns. Occlusal wear was significantly greater for PICN (0.45 ± 0.38 mm) compared with ZLS (0.16 ± 0.05 mm; p = 0.03). Both crown fractures occurred on BLT implants (82% survival), whereas PP implants showed 100% survival.

ZLS demonstrated the highest survival rate and no irreparable failures, along with significantly lower occlusal wear. PICN showed more catastrophic fractures and greater wear. Technical complications were frequent for both materials, independent of implant system or abutment height.

Deutsches Register Klinischer Studien (DRKS-ID: DRKS00026973).