When a posterior tooth needs more than a filling but does not justify a full crown, you are deciding between two conservative restorations: inlays and onlays. The distinction is mechanical and simple. An inlay sits within the tooth's occlusal surfaces and does not cover any cusp. An onlay extends over at least one cusp, wrapping the tooth like a partial cap and reinforcing it. An overlay covers all cusps.
At Istar Dental Lab, we manufacture inlays and onlays as full-service restoration work — CAD design, milling, sintering, layering, and final inspection handled in our own facilities in Shenzhen and Huizhou, China. This page covers the clinical decision first, then our materials and processes, then the practical details of working with us.
This is the first question worth answering, and it is a clinical decision rather than a laboratory one. Our value as a lab is to make that decision easier to execute well once you have made it.
Choosing the right inlay dental restoration — whether an inlay, onlay, or full crown — depends on the extent of tooth damage and the clinical priorities of durability, aesthetics, and conservation. Partial-coverage restorations preserve more healthy tooth structure than a full crown, which is the main clinical argument for them. They are not automatically the better choice, and several conditions work against them.
This is the question where published data most directly answers the concern clinicians raise most often — whether partial coverage restorations fail more than full crowns. The evidence is reassuring, and it is worth examining closely.
A 2018 systematic review that specifically compared inlays and onlays against complete coverage restorations reported mean survival rates of 90.89% for inlays, 93.50% for onlays, and 95.38% for crowns. Across all types, the 5-year survival rate exceeded 90%, and caries was the main biological complication while ceramic fracture was the most common technical complication. The authors noted that study heterogeneity prevented meaningful comparison between restoration types — the figures are pooled means rather than a head-to-head trial (Vagropoulou et al., 2018).
A separate 2016 meta-analysis of ceramic and resin inlays, onlays, and overlays found estimated survival rates for glass-ceramics and feldspathic porcelain between 92% and 95% at 5 years (n = 5,811 restorations) and 91% at 10 years (n = 2,154). In that analysis, fractures and chipping accounted for 4% of failures, followed by endodontic complications at 3%, secondary caries at 1%, and debonding at 1% (Morimoto et al., 2016).
Longer-term data come from a 2021 systematic review of ceramic and composite partial-coverage restorations. It reported survival of ceramic inlays and onlays of 90% at 5 years, 89% at 8 years, and 85% at 10 years, with success rates of 88% at 5 years and 77% at 10 years. Restoration fracture and endodontic complications were the dominant failure modes, while non-vital teeth and multiple-surface restorations tended to raise failure risk (Fan et al., 2021).
The longest mean follow-up among these studies is a practice-based retrospective evaluation of leucite-reinforced glass-ceramic restorations (IPS Empress) followed for 11.2 years on average. Overall survival was 80.3% (inlays 80.4%, onlays 80.0%), and the most frequent complications were ceramic fracture at 10.6% and chipping at 2.3% (Strasding et al., 2020).
One nuance is worth stating honestly: ceramic and resin are not equivalent here. A meta-regression comparing the two found ceramic partial-coverage restorations outperformed resin-based ones at both 5 and 10 years, with 5-year survival of 86% for resin versus 90% for feldspathic porcelain and 92% for glass ceramic. If resin composite is what you plan to use, expect different longevity than the ceramic figures above (Naik et al., 2022).
Material choice is where most of the real decision-making happens. The matrix below maps our available materials against the situations each one handles well.
Bonding method narrows the field, and it is worth deciding early.
If you are bonding a glass ceramic, the bonding protocol is not optional detail. Lithium disilicate requires hydrofluoric acid etching followed by silanization to achieve a reliable bond. We will flag any preparation design or surface treatment that would compromise adhesion before the case proceeds.
Every case runs in-house. Nothing is outsourced to a third-party lab, which means one team owns the case from data receipt to final inspection.
Design approval before production. You can review the design before milling or pressing. If you want changes at that point, tell your case coordinator. One thing to plan for: approved designs extend production by one to two days.
Our quality control is a separate department of approximately 25 staff, not a task folded into production. Roughly 460 people work across the company, including about 100 in CAD design and 70 in milling.
Our process treats root cause, not just replacement.
For standard cases we need either a physical impression with an occlusal rim, or intraoral scan data. Digital cases are faster end to end because there is no model to ship and no customs clearance to wait for; physical impressions add cross-border transit time on top of identical bench time.
If you are sending a physical impression internationally:
If you are sending digital data, send it by email or your data transfer platform.
References are welcome. We accept sketches, photos of the existing restoration, diagnostic wax-ups, and temporary restorations as guides. We can also mirror or copy morphology from an existing crown or from the contralateral tooth.
Standard laboratory production is 2–3 working days, calculated in working days from the day we receive the case.
What does not count against that clock: design approval waits, missing information being supplied, and time spent waiting for your reply. The clock restarts once we have complete information or your confirmation.
Also worth planning around:
Long-span and full-arch cases accumulate stitching error. To minimize it:
Full-arch cases are particularly prone to cross-arch error because edentulous areas lack natural tooth references and saliva and soft tissue interference cause software registration drift. Verification jigs can be used to check accuracy.
Every account has a designated manager and customer service team, on a fixed communication channel. Email, WhatsApp, and video meetings are all available, and we can hold technical case conferences in English.
Standard customer service hours are 9:30 am to 6:00 pm, extendable to midnight for special cases. Managers accommodate urgent cases outside those hours.
For feedback during try-in, we establish a WhatsApp group with a dedicated contact so trial feedback is written back into the final design.
Shipments go out through Istar's factory courier account, with access to factory bulk rate agreements. Outbound shipping is at your cost; for return shipments, the factory covers costs above a certain package value, and a portion is charged to the customer below that threshold.
Tracking numbers and estimated arrival times are provided on the dispatch day, and package follow-up is actively monitored until delivery. Shipping insurance is not included by default and can be purchased; the maximum claim covers processing fees or the insured value, not consequential loss.
If you need to change a delivery address, it can be done urgently before packing. Once shipped, we cannot intercept it — you will need to contact the carrier.
Splitting orders is possible before machining begins at the design stage. After milling or sintering, splitting generally is not possible and adds labor and shipping cost requiring approval.
We welcome visits to Shenzhen and Huizhou. Clinics, labs, and partners can arrange factory visits, production line tours, video factory inspections, and manufacturing capability discussions, so you can see the workflow and quality procedures directly.
Normal season: approximately 8,000 zirconia single crowns, 2,000 zirconia bridges, 20 All-on-X arches, and 4,000 removable dentures per month. Peak season roughly doubles this: 15,000 crowns, 3,000 bridges, 40 arches, and 6,500 dentures.
We maintain approximately 50 trained backup workers for peak season support. If a sudden large order would affect existing cases, we prioritize already-confirmed schedules, and negotiate split shipments or adjusted delivery dates for new orders rather than compressing quality standards. If production is disrupted by equipment failure or material shortage, we contact you proactively with the reason, estimated delay, and alternatives.
Ceramic partial-coverage restorations show survival rates of 92–95% at 5 years and about 91% at 10 years in pooled data. Onlays specifically report around 93.5%. Individual longevity depends heavily on the tooth's condition, the material, bonding quality, and the patient's parafunctional habits. Gold restorations are the longest-lasting option when they are appropriate.
They preserve more healthy tooth structure, which is their main advantage. They are not automatically better — when remaining tooth structure is limited, a crown is usually the more predictable choice. Survival rates for onlays and crowns are closer than often assumed, with pooled figures of 93.5% and 95.4% respectively.
Fractures and chipping are the leading cause, followed by endodontic complications, secondary caries, and debonding. Most of these trace back to preparation design, material choice, bonding quality, and occlusal load rather than to the restoration type itself. This is the area where careful preparation and design practice has the most effect.
With current chairside CAD/CAM this is sometimes possible, and some restorations are delivered same-day. It is not universally available, and the conditions for a one-visit workflow are specific — adequate digital data, sufficient time, and a clinical situation compatible with immediate fabrication. For cases we handle, standard production is 2–3 working days.
Shade selection involves layering rather than relying on a single shade tab. We recommend photos or video of the shade taken in natural light with the tooth clean and moist, ideally showing the natural tooth alongside a shade guide, plus the prepared tooth alongside a shade guide. This lets us judge whether masking is required and shade the restoration accurately against its neighbors. For multiple restorations on the same patient, we record and archive contour and morphology to keep them consistent.
Either a physical impression with an occlusal rim, or intraoral scan data. For anterior cases, shade photographs help considerably. References such as existing restorations, photos, wax-ups, or a temporary restoration are welcome and often useful.
Contact the sales manager for the B2B price list. Standard pricing logic is unit count as the base, material setting the baseline, with implant components and design complexity as additions. Design, models, components, packaging, and shipping are included in the quoted price.
Cases pause when information is incomplete or a technical question needs your input — a margin design unsuited to the material, a scan issue, or a missing reference. Your coordinator contacts you and notifies daily until the issue is resolved. The turnaround clock restarts once complete information is received.
Yes. Rush handling can be arranged before or after case submission, applies to all materials and case types, and carries no additional charge when volume is under ten cases per month. A specific arrival date can be committed.
The fastest way to find out whether we fit your workflow is to send one trial case. Send digital data by email or your transfer platform, or a physical impression by courier, and tell us the material and the case details. If you would rather start with a conversation, ask your sales manager for the B2B price list and material list, or request a technical case conference in English.
Want to get in touch directly? Reach out to our sales representative via WhatsApp at +8618925410015 for a quick response and a price quote!
