What Are Dental Inlays and Onlays? A Conservative Alternative to Crowns

vvigoren
Sep 1
3 min read

By Greg Vigoren, DDS

When decay or damage is more than a simple filling can handle—but a full crown would remove too much healthy tooth—inlays and onlays can be the sweet spot. At Vigoren Restorative Dentistry in Newport Beach, CA, we use high-magnification and precise adhesive techniques to restore strength and esthetics while preserving natural structure.

TL;DR

Conservative: Onlays/partial crowns remove ~35.5–46.7% of tooth structure vs. ~67.5–75.6% for full crowns (Edelhoff & Sorensen, 2002; corroborated in Wang et al., 2022).
Durable: Meta-analyses and JADA summaries report ~95% 5-year and ~91% 10-year survival for ceramic inlays/onlays (Morimoto et al., 2016; JADA Evidence Review, 2017).
Material matters: Cast gold inlays/onlays show the lowest annual failure (~1.4%) and exceptional longevity in posterior teeth (ADA topic page).
Best for: Moderate damage, cracks, or large replacements where a full crown may be avoidable.

What Is a Dental Inlay?

An inlay is a custom, lab-made restoration that fits within the grooves of a tooth (between cusps). It replaces decayed or failing material with high-strength ceramic, composite, or gold. Compared with large direct fillings, inlays provide precise contacts and margins and distribute occlusal loads more favorably (JADA overview).

What Is a Dental Onlay?

An onlay extends coverage to one or more cusps, reinforcing weakened tooth structure while still avoiding full circumferential reduction. In posterior teeth, onlays often deliver crown-like strength with less removal of healthy tissue. Systematic data show high clinical survival for ceramic onlays at 5–10 years (Morimoto et al.; JADA).

Why Choose Inlays/Onlays Instead of a Crown?

Tissue preservation: Classic quantification found full crowns remove ~67.5–75.6% of tooth structure, while onlays/partial crowns remove ~35.5–46.7% (Edelhoff & Sorensen; Wang et al.).
Proven longevity: Ceramic inlays/onlays ≈ 95% at 5 years, ~91% at 10 years (JADA evidence summary; Morimoto et al.).
Gold option: Cast gold inlays/onlays have exceptionally low annual failure and long service life in the posterior region (ADA topic page; see also Stoll et al., 1999).

How the Procedure Works (Gentle & Precise)

Diagnosis & planning: High-magnification exam; radiographs as indicated to evaluate cracks, caries extent, and remaining enamel.
Conservative prep: Only compromised tissue is removed; margins are finished under magnification for clean bonding surfaces.
Impressions & temporization: Digital or conventional impression; a temporary protects the tooth.
Bonding & finishing: The inlay/onlay is adhesively bonded, occlusion refined, and margins polished for a sealed, cleansable interface.

Evidence Snapshots

Ceramic inlays/onlays: Systematic review/meta-analysis—Journal of Dental Research—reports high survival at 5 and 10 years; fractures most common failure mode (Morimoto et al., 2016; JADA synopsis 2017).
Indirect composite inlays/onlays: 9-year prospective study showed acceptable long-term results (85% success at 9 years) (Galiatsatos et al., 2021).
Cast gold: Very low annual failure (~1.4%) and excellent longevity in posterior teeth (ADA topic page).

FAQs

What’s the difference between an inlay and an onlay?

Inlay fits within the cusps; onlay covers one or more cusps for extra reinforcement (JADA overview).

How long do inlays and onlays last?

Meta-analyses and evidence reviews suggest ceramic inlays/onlays survive about 95% at 5 years and ~91% at 10 years with proper placement and care (JADA; Morimoto et al.).

Are they better than a crown?

For moderate damage, yes—because they preserve significantly more tooth while still restoring strength. Severely compromised teeth may still need full crowns (Edelhoff & Sorensen).

Will the procedure hurt?

With modern local anesthesia and adhesive techniques, treatment is typically comfortable; most patients return to normal function quickly.

Next step: Wondering if you’re a candidate for a conservative onlay instead of a crown? Schedule a visit or call (949) 760-1152.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Individual results may vary. Please consult a licensed dentist for diagnosis and treatment.

Author Bio

Greg Vigoren, DDS is a restorative dentist in Newport Beach, CA. Over nearly 50 years, he has focused on precision, longevity, and tissue-preserving techniques using high magnification and advanced adhesive protocols.