Prevalence and associated factors of laboratory remakes in fixed prosthodontics: a multicenter audit in Riyadh, Saudi Arabia

Abstract

Remakes in fixed prosthodontics present ongoing clinical and logistical challenges, including increased chairside time, laboratory costs, and patient dissatisfaction. Understanding the prevalence and causes of these remakes is essential for improving restorative outcomes and workflow efficiency. This study aimed to estimate the prevalence of laboratory remakes for fixed prosthodontic restorations and examine associations with restoration type, material, and operator classification in a multicenter setting. We conducted a retrospective, multicenter audit of 40,344 indirect restorations fabricated in seven dental laboratories in Riyadh. Predefined null hypotheses posited no associations between remake reasons and (a) restoration type, (b) material, or (c) operator classification. Pearson χ² tests were used (α = 0.05). There were 2,612 remakes. By restoration, remake prevalence was veneers 7.5%, onlays 7.1%, crowns 6.9%, bridges 4.8%, and endocrowns 4.0%. Leading reasons were margin-fit discrepancy 29.5%, proximal-fit issue 23.2%, and improper fit 22.7%. Materials were differentially associated with remake reasons (e.g., shade mismatch more frequent with lithium-disilicate; proximal-fit problems more frequent with monolithic zirconia; all p < 0.05). Reason profiles differed by operator classification. Remakes were common and patterned by restoration type, material, and operator classification. Addressable targets include margins and proximal contacts, clearer laboratory prescriptions, and staged adoption of digital workflows with competency-based training. These observations can inform local quality-improvement initiatives.

Introduction

Fixed prosthodontic remakes consume clinical time, increase laboratory costs, and erode patient satisfaction (Alqahtani 2024; Al-Rafee et al. 2020; Ismail and Al-Moghrabi 2023; Tulbah et al. 2017). Although digital workflows have matured, remakes persist, often reflecting issues in tooth preparation, impression quality, or dentist–laboratory communication. Laboratory-based audits offer a pragmatic view of where and why failures cluster along the fabrication pathway.

Studies in Saudi Arabia and elsewhere have highlighted that suboptimal communication between dentists and dental laboratories is a leading contributor to remakes. A study by Tulbah et al. (2017) conducted in Riyadh revealed significant deficiencies in communication, especially in public-sector laboratories. These deficiencies were particularly prominent in the lack of detailed instructions on prosthesis design—such as porcelain selection, margin configuration, and pontic design—which are critical for clinical success. Furthermore, the experience level of the dental practitioner has been shown to inversely correlate with remake rates. Research by McCracken et al. (2019) and Al-Rafee et al. (2020) demonstrated that more experienced clinicians had significantly fewer instances of prosthetic remakes, highlighting the importance of clinical training and diagnostic acuity. Similarly, Albashaireh and Al Negrish (2001) highlighted that nearly 50% of impressions and casts in their study were technically deficient, citing blurred finish lines and improper occlusal reduction as the most common issues.

Technological integration has also shown promise in addressing these challenges. Binhuraib et al. (2023) emphasized that properly implemented digital workflows can enhance communication, minimize errors, and significantly reduce remake rates. Similarly, Alqahtani (2024) reviewed the application of 3D scanners and noted that high-quality digital impressions can eliminate many of the variables that contribute to conventional impression errors. However, as Ismail and Al-Moghrabi (2023) caution, the mere presence of technology is not sufficient without adequate training and consistent communication protocols between clinics and labs.

Despite these insights, the literature remains limited in providing a comprehensive, laboratory-based analysis of the prevalence and causes of remakes in fixed prosthodontics. While a 4% remake rate has been reported in broader contexts (McCracken et al. 2019), such figures often underestimate the complexity and multi-factorial nature of prosthetic failures in real-world clinical settings.

Additionally, most published estimates are single-center or clinic-based and may under-represent the laboratory perspective. We therefore conducted a multicenter audit across seven licensed laboratories in Riyadh to quantify remake prevalence and to test whether remake reasons differ by restoration type, material, operator classification, and communication mode. Findings are intended to be locally actionable, providing relevant targets for quality improvement.

Material and methods

Study setting and design

This retrospective, analytical cross-sectional audit was conducted in Riyadh, Saudi Arabia—a major hub for dental services with a wide range of public and private dental laboratories. Using a list of licensed facilities, seven licensed laboratories were randomly selected, and laboratory records from July 2022 to July 2023 were reviewed. The study was designed to characterize patterns and test associations in this metropolitan setting, rather than to provide a region-wide census. The protocol was approved by the King Abdullah International Medical Research Center (KAIMRC) Institutional Review Board (IRB) (Protocol No. RSS23R/008/07); because only de-identified data were used, informed consent was not required from individual patients or practitioners. However, permission to access and analyze the records was obtained from all participating dental laboratories. All study procedures and reporting were conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

Inclusion criteria and study sample

The study included 40,344 fixed prosthodontic restorations, including crowns, bridges, veneers, onlays, and endocrowns. Only indirect, laboratory-fabricated restorations were considered. Exclusion criteria were limited to removable or implant-supported prostheses. A total of 2,612 restorations were recorded as remakes, representing the cases of interest for our analysis.

Data collection procedures

A structured data extraction form was used to obtain information from laboratory logbooks and electronic records. Variables included type of restoration, dental material used, reason for remake, dentist communication method (paper or digital), and operator classification (student, general dentist, resident, or specialist). Reasons for remakes were extracted from laboratory records and categorized using standardized definitions established prior to data collection. Data extraction followed prior calibration on the use of these categories to ensure consistency. These included: “margin fit” for inadequate marginal adaptation and open/short margins; “improper fit” for general misfit unrelated to margins, proximal contacts, or occlusion—e.g., internal fit, path-of-insertion issues; “proximal fit” for incomplete seating at the mesial/distal aspect resulting in poor interproximal adaptation; “proximal contact” for open or overly tight contact between adjacent teeth when seating and margins are otherwise acceptable; “occlusal contact” for hyper- or hypo-occlusion, high spots, or open occlusion not attributable to incomplete seating; “crown contour” for over- or under-contoured axial/emergence profile or anatomic form inconsistent with the prescription, independent of contact or occlusal issues; “shade mismatch” for color discrepancies requiring refabrication; “esthetic concern” for appearance dissatisfaction not captured by shade or contour—e.g., surface texture, translucency/characterization, incisal edge morphology; “fracture” for bulk fracture, chipping, or delamination of ceramic/veneer; and “microcrack” for hairline crack without loss of structure. When multiple reasons were noted for a single unit, the primary reason indicated by the laboratory was retained. All investigators reviewed and agreed upon the definitions to maintain consistent classification. Prior to data extraction, they participated in a structured calibration session to ensure consistent application of the predefined remake-reason categories. During this process, the team jointly reviewed a sample set of laboratory records, discussed the operational definitions of each category, and resolved discrepancies through consensus. This calibration ensured uniform interpretation of the classification scheme during the full data-extraction phase.

Demographic data were not collected to preserve focus on clinical and technical parameters. All data were consolidated in Microsoft Excel before analysis. For each operator group, the total number of restorations fabricated could not always be retrieved from all laboratory records; therefore, remake rates per operator should be interpreted descriptively. Future audits will capture operator-level denominators to enable normalized remake-rate analysis.

Statistical analysis

Analysis was performed using NCSS 2020 (NCSS, LLC; Kaysville, Utah, USA). Descriptive statistics were used to summarize the prevalence and distribution of remakes, restoration types, operator categories, and material usage. Associations between categorical variables including restoration type, remake reasons, material type, and practitioner classification were examined using the chi-square (χ²) test. A 95% confidence interval (CI) was calculated for remake prevalence, and a p-value of < 0.05 was considered statistically significant. All tests were two-tailed. Significant associations were further explored to interpret potential clinical implications.

Results

Prevalence of remakes

During the 12-month study period (July 2022 to July 2023), a total of 40,344 fixed prosthodontic restorations were fabricated across seven dental laboratories in Riyadh. Among these, 2,612 restorations required remakes, yielding an overall remake prevalence of 6.5% (95% CI: 6.2–6.8%).

Table 1 and Fig. 1 present remake rates across restoration types. Veneers demonstrated the highest remake rate at 7.5%, followed by onlays (7.1%), crowns (6.9%), bridges (4.8%), and endocrowns (4%).

Table 1.

Prevalence of remakes in fixed prosthodontic restorations by type in riyadh dental laboratories

Type of Restoration	Remakes	Total Produced	Remake Prevalence (%)	95% CI (Lower)	95% CI (Upper)
Crown	1518	22,136	6.9	6.5	7.2
Veneer	467	6,238	7.5	6.9	8.2
Onlay	221	3,103	7.1	6.3	8.1
Endocrown	108	2,729	4.0	3.3	4.8
Bridge	297	6,138	4.8	4.3	5.4

Fig. 1.

Remake prevalence by type of fixed prosthodontic restoration

Distribution by operator category

Operator-level analysis indicated a trend in the composition of remade units by operator seniority. The highest prevalence was observed among dental students (28.8%), followed by general dentists (10.3%), residents (4.3%), and specialists (2.7%). These figures highlight a notable decrease in remake rates with increasing operator experience (Table 2 and Fig. 2).

Table 2.

Characteristics of remade fixed prosthodontic restorations (n = 2,612)

Category	Variable	n (%)
Type of Restoration	Crown	1,518 (58.1%)
	Veneer	467 (17.9%)
	Onlay	221 (8.5%)
	Endocrown	108 (4.1%)
	Bridge	297 (11.4%)
Material of Restoration	Emax	1,118 (42.8%)
	Monolithic zirconia	956 (36.6%)
	Layered zirconia	410 (15.7%)
	Porcelain-fused-to-metal (PFM)	127 (4.9%)
	Metal	1 (0.04%)
Reasons for Remake	Margin fit	771 (29.5%)
	Proximal fit	606 (23.2%)
	Improper fit	594 (22.7%)
	Shade mismatch	426 (16.3%)
	Esthetic concerns	404 (15.5%)
	Crown contour	270 (10.3%)
	Proximal contact	248 (9.5%)
	Occlusal contact	232 (8.9%)
	Microcrack	190 (7.3%)
	Fracture	110 (4.2%)
Communication Mode	Paper-based	2,427 (92.9%)
	Computer-based (digital)	185 (7.1%)
Practitioner Classification	General Dentist	1,487 (56.9%)
	Specialist	462 (17.7%)
	Dental Resident	318 (12.2%)
	Dental Student	345 (13.2%)

Fig. 2.

Distribution of remade units by operator group

In terms of contribution to the total number of fabricated restorations, general dentists accounted for the majority of cases (56.9%), followed by specialists (17.7%), dental students (13.2%), and residents (12.2%). This distribution highlights the clinical workload pattern and emphasizes the relative impact of each practitioner group on overall remake volume.

Restoration and material characteristics

Among the 2,612 remade units analyzed, the majority were crowns (58.1%), veneers (17.9%), and bridges (11.4%), with smaller contributions from onlays and endocrowns. In terms of materials, Emax restorations were most frequently remade (42.8%), followed by monolithic zirconia (36.6%), layered zirconia (15.7%), PFM (4.9%), and metal (0.04%). Communication between clinicians and laboratories was overwhelmingly paper-based (92.9%), with minimal use of computer-based communication (7.1%) (Table 2).

Communication mode

Among the remade restorations, the vast majority originated from paper-based submissions (92.9%), while only a small proportion were linked to digitally submitted prescriptions (7.1%). Because laboratory records did not consistently document the total number of restorations submitted via each communication mode across all fabricated cases, remake rates for digital versus paper-based submissions could not be calculated. Accordingly, statistical comparisons between communication modes were not performed. Nonetheless, the very limited use of digital communication highlights a potential area for workflow improvement.

Reasons for remakes

The most common reasons for remakes were margin fit discrepancies (29.5%), proximal fit issues (23.2%), and overall improper fit (22.7%). Other significant causes included esthetic dissatisfaction (15.5%), shade mismatch (16.3%), occlusal contact errors (8.9%), and poor crown contour (10.3%) (Table 2, Fig. 3).

Fig. 3.

Prevalence of remake reasons in fixed prosthodontic restorations

Association between restoration type and remake reason

There was a statistically significant association between the type of restoration and all evaluated reasons for remakes (p < 0.0001). Among crowns, the most frequently reported issues were margin fit discrepancies (37.5%), proximal fit (25.2%), and improper fit (20.4%). For veneers, esthetic concerns (35.3%), poor shade matching (39%), and fractures (17.6%) were predominant reasons for remakes. Onlays showed the highest rates of improper fit (39.4%) and proximal fit issues (43%), with notable occurrences of occlusal contact problems (18.6%). In bridges, remakes were most commonly associated with improper fit (25.3%), proximal fit (26.3%), and occlusal discrepancies (23.2%). Endocrowns had the highest remake rates due to improper fit (42.6%), margin fit (39.8%), and occlusal contact issues (26.9%). While microcracks and fractures were generally less common, fractures were particularly prevalent in veneers (17.6%). Poor crown contour was mostly seen in veneers (14.1%) and bridges (20.5%). Esthetic issues were negligible for endocrowns (0%) but represented a frequent concern in veneers and crowns. Overall, all differences between restoration types and remake reasons were statistically significant (p < 0.0001), underscoring a strong association between restoration type and the nature of complications encountered (Table 3).

Table 3.

Significant associations between type of fixed prosthodontic restoration and reasons for remake

Reasons for Remakes		Type of restoration
	Category	Crowns n(%)	Veneers n(%)	Onlays n(%)	Bridges n(%)	Endocrowns n(%)	p-value*
Improper fit	Yes	310(20.4)	76(16.2)	87(39.4)	75(25.3)	46(42.6)	75.8(4)  <.0001*
	No	1208(79.6)	391(83.7)	134(60.6)	222(74.8)	62(57.4)
Proximal fit	Yes	383(25.2)	12(2.6)	95(43)	78(26.3)	37(34.3)	172.75(4)  <.0001*
	No	1135(74.8)	455(97.4)	126(57.0)	219(73.7)	71(65.7)
Margin fit	Yes	569(37.5)	30(6.4)	63(28.5)	66(22.2)	43(39.8)	179.18(4)  <.0001*
	No	949(62.5)	437(93.6)	158(71.5)	231(77.8)	65(60.2)
Microcrack	Yes	77(5.1)	74(15.9)	4(1.8)	31(10.4)	4(3.7)	77.98(4)  <.0001*
	No	1441(94.9)	393(84.2)	217(98.2)	266(89.6)	104(96.3)
Fracture	Yes	14(0.9)	82(17.6)	12(5.4)	2(0.7)	0(0)	261.63(4)  <.0001*
	No	1504(99.1)	385(82.4)	209(94.6)	295(99.3)	108(100)
Proximal contact	Yes	163(10.7)	19(4.1)	38(17.2)	12(4.0)	16(14.8)	47.8(4)  <.0001*
	No	1355(89.3)	448(95.9)	183(82.8)	285(96)	92(85.2)
Occlusal contact	Yes	93(6.1)	0(0)	41(18.6)	69(23.2)	29(26.9)	203.89(4)  <.0001*
	No	1425(93.9)	467(100)	180(81.5)	228(76.8)	79(73.2)
Crown contour	Yes	140(9.2)	66(14.1)	0(0)	61(20.5)	3(2.8)	74.75(4)  <.0001*
	No	1378(90.8)	401(85.9)	221(100)	236(79.5)	105(97.2)
Shade mismatch	Yes	156(10.3)	182(39)	2(0.9)	81(27.3)	5(4.6)	291.47(4)  < 0.0001*
	No	1362(89.7)	285(61.0)	219(99.1)	216(72.7)	103(95.4)
Esthetic concerns	Yes	179(11.8)	165(35.3)	5(2.3)	55(18.5)	0(0)	207.9(4)  < 0.0001*
	No	1339(88.2)	302(64.7)	216(97.7)	242(81.5)	108(100)

Association between clinicians’ classification and remake cause

The analysis revealed notable variations in crown remake reasons across dentist classes. Margin fit discrepancies was the most common issue overall, particularly among dental students (34.8%) and residents (30.8%). Improper fit was prevalent among specialists (28.4%) and residents (26.1%), while proximal fit affected 23.4% of general dentists’ cases. Esthetic concerns were consistently reported across all groups (11–17.3%), with the highest rate among general dentists (17.2%). Fractures were uncommon across all groups (2.3–6.0%), with the highest rate in residents (6.0%). Within the subset of remakes, the distribution by operator group suggests that experience and case mix may shape failure modes: trainees more often recorded margin-fit discrepancies, whereas specialists’ remakes clustered around general/internal fit issues; general dentists showed more proximal-fit problems (Table 4).

Table 4.

Distribution of remake reasons by practitioner rank

	Specialist	Dental resident	General dentist	Dental student
Improper fit	28.4%	26.1%	21%	19.7%
Proximal fit	20.1%	19.5%	23.4%	29.9%
Margin fit	24.2%	30.8%	29.7%	34.8%
Microcrack	5.6%	5%	7.9%	9%
Fracture	4.8%	6%	4.1%	2.3%
Proximal contact	8%	3.8%	10.2%	13.6%
Occlusal contact	8.7%	10.7%	7.8%	12.2%
Crown contour	7.6%	7.9%	11.6%	10.7%
Shade mismatch	15.8%	17.3%	17.3%	11.9%
Esthetic concerns	12.3%	11%	17.2%	16.2%

Association between remake reasons and type of material

The analysis revealed significant associations between all remake reasons and material types (all p < 0.05). PFM crowns showed the highest rates of contour issues (24.4%, χ² = 45.3, p < 0.0001) and improper fit (32.3%, χ² = 11.4, p = 0.0221), while monolithic zirconia demonstrated elevated prevalence of proximal fit problems (29.8%, χ² = 96.8, p < 0.0001). Emax crowns were most associated with cracks (10.3%, χ² = 26.8, p < 0.0001) and shade mismatches (23.6%, χ² = 291.5, p < 0.0001). Layered zirconia performed best for occlusal contacts (7.6% remake rate) and showed the lowest rates of fractures (0.5%). Metal crowns, while having the smallest sample size (n = 1), showed remake due to improper fit (100%) (Table 5).

Table 5.

Significant associations between remake reasons and dental materials

Remake Reason	Material	Remake Cases	Total Cases	Remake %	χ2(df = 4)	p-value
Improper Fit	PFM	41	127	32.3%	11.4	0.0221*
	Monolithic Zirconia	223	956	23.3%
	Emax	242	1118	21.6%
	Layered Zirconia	87	409	21.3%
	Metal	1	1	100%
Proximal Fit	Layered Zirconia	136	409	33.3%	96.8	< 0.0001*
	Monolithic Zirconia	285	956	29.8%
	Emax	163	1118	14.6%
	PFM	21	127	16.5%
	Metal	0	1	0%
Margin Fit	Monolithic Zirconia	385	956	40.3%	89.3	< 0.0001*
	PFM	49	127	38.6%
	Layered Zirconia	112	409	27.4%
	Emax	241	1118	21.6%
	Metal	0	1	0%
Crown contour	PFM	31	127	24.4%	45.3	< 0.0001*
	Layered Zirconia	53	409	13.0%
	Emax	123	1118	11.0%
	Monolithic Zirconia	63	956	6.6%
	Metal	0	1	0%
Crack	Emax	115	1118	10.3%	26.8	< 0.0001*
	PFM	8	127	6.3%
	Layered Zirconia	22	409	5.4%
	Monolithic Zirconia	45	956	4.7%
	Metal	0	1	0%

P-values for differences based on chi-squared test for proportions and Fisher's exact test

^*Differences significant at P ≤ 0.05

Discussion

This multicenter laboratory audit provides a metropolitan snapshot of remake patterns in fixed prosthodontics and highlights a set of modifiable drivers such as margin-fit, proximal-fit, and general/internal fit, shaped by restoration type, material, and operator group.

The overall remake prevalence of 6.5% found in this study exceeds prior estimates, such as those by McCracken et al. (2019), who reported a 4% remake rate across various prosthodontic cases. This discrepancy may reflect differences in operator experience, regional procedural standards, and communication effectiveness between dentists and technicians.

Among the restoration types analyzed, veneers (7.5%), onlays (7.1%), and crowns (6.9%) showed the highest remake rates. Veneer remakes skew toward esthetic/shade concerns, whereas crowns/endocrowns show more margin-related issues—patterns consistent with previous research (Sulaiman et al. 2015). Endocrowns and bridges, which are more complex and technique-sensitive, showed lower remake rates, this may reflect case selection and indication thresholds rather than intrinsic ease.

The data confirm a trend in the composition of remade units by operator seniority: dental students had a remarkably high rate (28.8%), followed by general dentists (10.3%), residents (4.3%), and specialists (2.7%). This finding aligns with global evidence from Schwass et al. (2013) and Al-Rafee et al. (2020), who emphasize that early-career clinicians often struggle with impression accuracy, occlusal clearance, and communication protocols, leading to higher remake rates. Moreover, previous reports also found that the least experienced clinicians were more likely to accept inadequate impressions and had higher rejection rates from dental laboratories (Rau et al. 2017).

Within the subset of remade units, reason profiles differed by operator group—trainees more often recorded margin-fit discrepancies, specialists’ remakes clustered around general/internal fit, and general dentists showed relatively more proximal-fit issues (Tables 2 and 4).

Although digital prescriptions represented only 7.1% of the remade cases, this figure reflects the overall low adoption of digital communication rather than a true comparison of remake performance. Because operator- and laboratory-level denominators for digital versus paper-based submissions were not uniformly recorded, remake rates could not be compared, and inferential statistical analysis was not appropriate. This limitation is consistent with previous reports noting inconsistent documentation of communication channels in laboratory systems. Nevertheless, the overwhelming reliance on paper-based communication (92.9%) between dentists and laboratories in this study presents a key area for improvement. Moussaoui et al. (2024), reported that over 86% of laboratory technicians in private clinics received incomplete or unclear work authorizations, resulting in fabrication errors and remake requests, supporting the need for standardized communication templates. Similarly, Imbery et al. (2016), found that the quality of work authorizations submitted by dental students was a critical determinant of laboratory success, with poorly written forms significantly increasing the incidence of remakes. Furthermore, McCracken et al. (2020), conducted a multi-center assessment that revealed lab technicians frequently identified suboptimal crown preparations and impressions as the leading cause of unacceptable prostheses, often due to poor information flow on the laboratory prescription. Consistent with findings by Alammari and Albagar (2018), substandard laboratory prescriptions often lead to misunderstandings in shade selection, margin placement, and contouring, culminating in preventable remakes.

Digital workflows, when properly utilized, have demonstrated reduced error rates and improved turnaround (Afzal et al. 2022). However, the benefits of digital communication are contingent on adequate training and calibration between parties involved. Beyond impression capture, recent studies show that AI-assisted crown-design systems can reproduce morphology with acceptable accuracy but exhibit variability in internal fit and in the intensity and number of occlusal and proximal contacts. Feasibility studies indicate promise but also the need for further optimization and clinical validation (Cho et al. 2024). Systematic and scoping reviews likewise conclude that evidence for fully digital/AI workflows is encouraging but heterogeneous and not yet definitive, especially for multi-unit reconstructions (Chau et al. 2024).

Material-specific patterns in remake reasons were evident (e.g., more shade mismatch in lithium-disilicate, more proximal/margin-fit issues in monolithic zirconia) (Table 5). These likely reflect trade-offs between esthetic fidelity and seating tolerance rather than inherent ‘defects’ of any material; hence indication-to-material alignment and clear prescriptions remain pivotal, but in alignment with previous research (Sulaiman et al. 2015).

Conversely, PFM restorations, though used less frequently, exhibited the highest rate of improper fit and contour errors, suggesting challenges in traditional metal-ceramic workflows, particularly when occlusal schemes are not clearly communicated. The results also reinforce the superior fracture resistance of monolithic zirconia, but highlight its vulnerability to marginal and proximal fit errors when inadequate preparation or scanning occurs.

Our top categories (margins, proximal fit, and general/internal fit), mirror prior reports and cluster where preparation precision and interproximal adaptation are most demanding, reinforcing the need for case-specific protocols in preparation, impression/scanning, and laboratory instruction (Rau et al. 2017; Yunus et al. 2015).

Internationally, remake prevalence for fixed prosthodontics ranges between 4 and 7% (McCracken et al. 2019; Schwass et al. 2013; Sulaiman et al. 2015), which positions the present Riyadh multicenter rate (6.5%) within the global spectrum. Variations may reflect local training models, technician calibration, and digital integration levels, emphasizing the need for standardized communication and digital literacy across contexts.

Practice implications include: (i) Standardize prescriptions (finish line/margin design, target contact location & intensity, occlusion scheme, shade protocol with photos/scans); (ii) Digitize high-yield steps (intraoral scanning for cases at risk of margin/contact error; digital articulation); and (iii) Deploy AI-assisted Quality Assurance where evidence is strongest (finish-line detection; contact/margin checkers) as a guard-rail rather than a replacement for clinical judgment. As supported by Schlenz et al. (2020), digitally integrated simulation training and real-time feedback systems have been effective in reducing error rates among dental students.

Beyond clinical consequences, remakes impose additional costs and workflow disruption. Practice-based data indicate that a single crown preparation visit typically occupies about 60–90 min of chair time, and economic analyses suggest that repeating impression and fabrication procedures can add material and labor costs in the order of several hundred US dollars once lost productivity is considered (Minyé et al. 2018). Extrapolated to the 2,612 remakes observed in this audit, this represents a substantial economic and time burden for clinics and laboratories, even though precise local cost estimates were beyond the scope of this study.

This study strengths include the multicenter, real-world scope across seven licensed laboratories and reason-level classification aligned to pragmatic quality improvement targets. Limitations include incomplete operator-level denominators preventing precise remake-rate calculation per operator category, retrospective design, and potential under-recording; incomplete capture of laboratory digital capability (e.g., scanner/CAD use); operator-level denominators not consistently available, precluding firm comparisons of operator-specific remake prevalence; and single-metropolitan sampling, which limits external generalizability, particularly to settings with higher digital/AI adoption.

Future work should test a bundled quality improvement package (structured prescriptions + targeted digital capture + AI-assisted quality assurance), with pre/post remake outcomes, time/cost, and reason profiles; add tooth/arch and lab digital-capacity fields to enable clustered modeling; and develop operator-tailored training (finish-line capture for trainees; internal-fit diagnostics for specialists; proximal adaptation for general dentists).

Conclusion

In this multicenter, laboratory-based audit from Riyadh, remakes clustered around margin adaptation and proximal-fit problems, varying by restoration type, material, and operator group. To reduce remakes, we recommend three immediate levers: (1) standardized prescriptions specifying finish line, target proximal contact, occlusion scheme, and a shade protocol with photos/scans; (2) indication-to-material choices matched to case complexity and operator competence; and (3) staged digital adoption with competency-based training, using AI-assisted checks as guard-rails. Evaluate impact with before–after quality-improvement cycles tracking remake prevalence, time, and cost. Findings are most applicable to similar urban laboratory ecosystems.

Author contributions

Conceptualization, L.K., F.F. and M.S.; methodology, L.K., F.F. and M.S. validation, L.K., F.F. and M.S.; formal analysis, F.F.; investigation, M.S., K.A., S.A., R.A., M.M. and N.A.; data curation, M.S.; writing—original draft preparation, L.K., F.F. and M.S..; writing—review and editing, L.K., F.F., M.S., K.A., S.A., R.A., M.M. and N.A.; supervision, L.K. and F.F.; project administration, M.S.; All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval

The protocol was approved by the King Abdullah International Medical Research Center (KAIMRC) Institutional Review Board (IRB) (Protocol No. RSS23R/008/07)

Informed consent

Because only de-identified data were used, informed consent was not required from individual patients or practitioners. However, permission to access and analyze the records was obtained from all participating dental laboratories.

Competing interests

The authors report no conflicts of interest in this work.