Time-and-motion study on class II copy-milled ceramic inlays

Area of Science:

• Dental materials science
• Clinical dentistry
• Biomaterials engineering

Background:

• Ceramic inlays offer a conservative alternative to amalgam restorations.
• Copy-milling technology enables precise fabrication of indirect restorations.
• Understanding working times is crucial for assessing the clinical efficiency of ceramic inlays.

Purpose of the Study:

• To estimate the total working time for Class II copy-milled ceramic inlays.
• To identify factors influencing the clinical and laboratory working times.
• To evaluate the efficiency of ceramic inlay placement.

Main Methods:

• A controlled clinical trial involving 173 ceramic inlays (Celay system) placed in 101 patients by seven dentists.
• Net working times for both clinical treatment and laboratory stages were recorded.
• Analysis of variance (ANOVA) was used to assess the influence of variables on working time.

Main Results:

• The mean clinical treatment time was 67 minutes, and the laboratory stage averaged 60 minutes.
• Cavity modification technique, operator, and restoration size significantly impacted clinical working time (p<0.001).
• Dentists demonstrated a 25% improvement in working time by the study's conclusion.

Conclusions:

• Class II copy-milled ceramic inlays require approximately 125 minutes of total working time.
• Composite basing and larger restorations increased working time.
• Operator experience and learning curve significantly affected efficiency, with dentists requiring more lab time than technicians.