Onlay Preparation and Ceramic Restoration Principles

Vocabulary practice cards focusing on the terminology, scientific studies, measurements, and clinical procedures involved in dental onlay preparations and ceramic material science based on the lecture transcript.

Total Occlusal Convergence

A term used in prosthodontics to describe the ideal taper of the opposing walls in a tooth preparation, which is ideally $6^\text{o}$.

Ideal Preparation Height

The recommended vertical height for a tooth preparation to provide adequate retention and resistance form, which is $4\text{ mm}$.

Emax (Lithium Disilicate)

A high-strength ceramic material from Ivoclar known for high fracture toughness and resistance to crack propagation, composed of approximately 70\text{%} crystalline structure and 30\text{%} amorphous glass.

Hydrofluoric Acid Etch

A chemical treatment used on lithium disilicate to selectively remove the glass matrix and create a micromechanical retentive surface.

Silane Coupling Agent

A chemical agent applied to an etched ceramic surface to improve the bond between the ceramic and the resin cement.

Looting Material

A material that fills the space between the tooth preparation and the restoration to interconnect surface roughness, but lacks a true adhesive seal.

Cuspal Flexure

The degree to which tooth cusps bend under load; increased by the removal of tooth structure, especially marginal ridges.

Supporting Cusp Margin

The specific preparation design for the cusp that bears occlusal load (buccal in mandibular, lingual in maxillary), which typically requires a shoulder margin of at least $1.0\text{ mm}$ or a $110^\text{o}$ angle.

Non-supporting Cusp Margin

The preparation design for the cusp that does not bear primary occlusal load, typically finished with a $45^\text{o}$ hollow ground bevel into the enamel.

Enamel Cross-sectioning

The practice of preparing enamel perpendicular to the enamel rods, which Marco Vargas found increases bond strength by more than three times compared to parallel preparation.

Bill Douglas Stiffness Study

Research indicating that tooth stiffness is reduced by 20\text{%} with an occlusal prep, 50\text{%} with one marginal ridge removed, and 65\text{%} when both marginal ridges are removed.

Temporary Restoration (Provisional)

The clinical prototype for the final restoration used to verify sufficient occlusal reduction ($1.0\text{ mm}$ to $1.5\text{ mm}$ thickness) and establish functional and aesthetic approval from the patient.

Sclerosis of Dentinal Tubules

The hardening of tooth tubules through the deposition of secondary dentin, typically found in older patients, which increases the threshold for pain/sensitivity.

Retention Grooves

Supplementary preparation features placed mesially and distally on a single crown to shorten the arc of rotation and improve resistance form.

Madame Butterfly Silk Ribbon

A specific type of articulating material used to mark occlusal contacts to ensure the restoration is not high in occlusion.

End Cutting Diamond

A 'tissue-protecting' bur with a smooth side used to create a clean, linear finish line on the shoulder margin without damaging neighboring soft tissue or creating undercuts.

Red Banded Finishing Diamond

A $30\text{ micron}$ grit diamond bur used to smooth tooth preparations and achieve the necessary cross-sectioning of enamel for adhesive bonding.

Ceramic Root Canal Statistic

Data indicating that approximately 9\text{%} of teeth with fixed ceramic restorations in the United States require a root canal within the first year after placement.

75 ext{%} Rule

A general clinical guideline used to determine when an extracoronal restoration (like an onlay or crown) is necessary because coronal tooth structure loss exceeds this threshold of the intercuspal width.