Clinical Effectiveness of CAD/CAM Temporary Resin Crowns in Implant Prosthodontic Protocols

Анотація

Relevance. Provisional fixed restorations are a critical component of the prosthetic phase in dental implantology. They serve multiple essential functions: ensuring controlled functional loading, guiding the biological shaping of peri-implant soft tissues (emergence profile), and allowing for the assessment and optimization of the final restoration’s aesthetics. The integration of CAD/CAM technologies enables the fabrication of temporary crowns with superior precision, predictable occlusal morphology, and enhanced marginal integrity compared to traditional chairside methods.

Aim of the Study. To evaluate the clinical performance and structural stability of milled CAD/CAM resin temporary crowns supported by dental implants during the osseointegration period and soft tissue maturation phase.

Materials and Methods: The study included 16 patients with partial edentulism (9 females, 7 males; mean age 42 ± 2.1 years). A total of 64 temporary crowns were fabricated, supported by both dental implants and natural teeth. The patients were divided into two groups based on the fabrication protocol:

• Group L/p (Control): 9 patients, 36 units fabricated using conventional laboratory thermopolymerization.
• Group Fr (Experimental): 7 patients, 28 units fabricated via CAD/CAM milling using Vita CAD-Temp blocks.

The observation period ranged from 2 to 6 months, with follow-up clinical examinations conducted at 3 and 9 months post-insertion. The evaluation focused on the following criteria:

1. Mechanical Stability: Resistance to fractures and chipping.
2. Physical Properties: Color stability and maintenance of occlusal contacts.
3. Biological Response: Evaluation of oral hygiene, biocompatibility, and microcirculation (via laser Doppler flowmetry or clinical assessment).
4. Periodontal Status: Assessment of peri-implant/periodontal health using the PMA (Papillary-Marginal-Attached) index and standardized Hygiene Indices.

Results. The comparative clinical analysis revealed a significant reduction in the overall complication rate for the digital protocol. The incidence of complications was 37.5% in the Laboratory Polymerization (L/p) group, compared to only 12.5% in the Milled CAD/CAM (Fr) group. This represents a 25% increase in clinical effectiveness when utilizing the CAD/CAM workflow.
The specific performance parameters favored the milled restorations across all evaluated categories:

• The rate of mechanical failures (fractures or chipping) decreased from 41.7% in the L/p group to 21.4% in the Fr group.
• Milled crowns exhibited a significantly lower negative impact on peri-implant and gingival tissues (17.9% vs. 58.3%), likely due to superior surface biocompatibility and reduced biofilm accumulation.
• Decementation rates were reduced from 33.3% to 10.7%, while the loss of occlusal contacts dropped from 30.6% to 7.1%.
  Stability of color and surface texture was significantly better in the CAD/CAM group (21.4% complication rate vs. 55.6% in the L/p group).
• The Hygiene Index was lower (indicating better hygiene) in the CAD/CAM group (25.8%) compared to the laboratory group (29.6%).

Conclusions. Milled CAD/CAM temporary resin crowns demonstrate significant clinical advantages over conventional laboratory-polymerized restorations, specifically:
A significantly lower inflammatory response in peri-implant tissues and more stable oral hygiene parameters.
Favorable microcirculation dynamics in the gingival margin, supporting faster and more predictable soft tissue maturation.
High structural strength and superior biocompatibility, ensuring stability throughout the osseointegration phase.

1. Recommendation: 
   CAD/CAM milled temporary crowns are highly recommended for complex prosthetic cases where the provisional phase is planned to exceed 3 months, especially in the “aesthetic zone” or during multi-stage implant protocols.
2. Laboratory-polymerized crowns remain a viable and cost-effective option only for short-term restoration (less than 3 months) where minimal soft tissue contouring is required.