Comparison of trueness and margin quality of additively and subtractively manufactured definitive resin-based laminate veneers

Additively manufactured zirconia periodontal splint integrated prosthesis: A proof-of-concept

OBJECTIVES

To provide a digital workflow for designing custom zirconia periodontal splints using material jetting (MJ) technology to support and rehabilitate periodontally compromised anterior teeth.

METHODS

Initially, the maxillary and mandibular teeth were scanned using a Trios3 intraoral scanner (IOS). Subsequently, the periodontal splint was digitally designed using a computer-aided design software. Then, a zirconia periodontal splint was produced using MJ technology with a three-dimensional (3D) printer (Carmel 1400C). Additionally, the trueness of the periodontal splint was analyzed using 3D detection software (Geomagic Control X 2018). Finally, the periodontal splint was adhered using resin cement.

RESULTS

In terms of trueness, the intaglio surface and the prosthesis of the periodontal splint matched well, whereas the lingual surface showed some deviation areas. The trueness root mean square (RMS) value of the splint was 57.7 μm and the deviation remained within ± 200 μm. For clinical treatment, the periodontal splint was precisely bonded and achieved the effect of supporting and rehabilitating periodontally compromised anterior teeth. After six months of treatment, the follow-up results showed that the splint remained intact, with no further absorption of the alveolar bone.

CONCLUSIONS

Additively manufactured zirconia periodontal splints exhibit good trueness and aesthetics. Periodontal splints can achieve precise bonding and maintain long-term bonding stability, and can help stabilize loosened teeth and prevent further absorption by the alveolar bone.

CLINICAL SIGNIFICANCE

This proof-of-concept outlines a digital workflow for designing zirconia periodontal splints using MJ technology to improve outcomes of periodontitis treatments. Moreover, the adhesive stability and efficacy of periodontitis treatment using the periodontal splint were preliminarily verified.

Trueness of multichromatic versus monochromatic veneers printed using tilted stereolithography technology at different build angles? An in vitro study

OBJECTIVES

To evaluate the influence of shade (monochromatic vs multichromatic) and build angle on the trueness of veneers printed using tilted stereolithography technology (TSLA).

METHODS

A maxillary central incisor typodont tooth model was prepared to receive a butt-joint full veneer with 0.3 mm labial and 2 mm incisal reduction. The preparation was digitized using laboratory scanner (T310; Medit) to design the veneer restoration. Sixty veneers were fabricated using Tilting Stereolithography (TSLA) 3D-printing technique (Dfab; DWS). Thirty veneers were printed in monochromatic shade (N = 30) (IrixMax monochromatic A2; DWS) and thirty veneers in multichromatic shade (N = 30) (A1-A3.5) using hybrid resin-ceramic material (IrixMax Photoshade A1-A3.5; DWS). In each group, three subgroups were defined based on the build angle (N = 10): 90°, 75° and 45° angles. Trueness was evaluated quantitatively and qualitatively using metrology software (Geomagic Control v2020; 3DSystems). Two-way Analysis of Variance (ANOVA) test with Tukey post hoc test for multiple comparisons were used to detect the differences in root mean square estimate (RMSE) between the test groups (α =0.05).

RESULTS

Two-way ANOVA revealed a statistically significant interaction between different build angles and material shade on RMSE in butt-joint veneer preparation design (P = .001). Multichromatic shade showed significantly higher RMSE values when printed at 45° (P=.010) compared to monochromatic one.

CONCLUSIONS

Build angle and material shade have an influence on the trueness of veneers printed using TSLA technique. 45° build angle with multichromatic shade material resulted in the highest RMSE deviation values. Therefore, clinicians should be cautious with the selected print angle when printing a multichromatic resin-based veneers.

STATEMENT OF CLINICAL RELEVANCE

Advances in material science and 3D-printers resulted in the introduction of a chairside TSLA 3D-printer that can be used for the fabrication of multichromatic, resin-based veneer restorations. Both build angle and material shade influence the dimensional accuracy of TSLA printed veneer restorations. To print highly accurate multichromatic restorations and increase the number of printed parts per print cycle, 45° build angle should be avoided.

Trueness, precision, and internal fit of additively and subtractively manufactured definitive resin-based crowns

PURPOSE

To assess the fabrication trueness, precision, and internal fit of additively manufactured (AM) and subtractively manufactured (SM) resin-based definitive crowns.

MATERIALS AND METHODS

A maxillary right first molar complete-coverage crown was designed and fabricated using 2 additively manufactured [Pro Resins Crown X (AM-S); Straumann USA LLC and Flexcera Smile Ultra+ (AM-F); Desktop Health] and 2 subtractively manufactured [Shofu HC (SM-S); SHOFU Dental Corp and Brilliant Crios (SM-C); Coltene/Whaledent AG] resins (n = 15). The crowns were scanned using an intraoral scanner (IOS) and then seated onto the abutment tooth and rescanned. Fabrication trueness was evaluated by superimposing test data (TD) over the reference crown and computing the root mean square (RMS, µm) error for overall, intaglio, and margin surfaces. Internal fit was evaluated by measuring the average gap distance between the crown and abutment tooth (µm) using a modified triple scan protocol (TSP) for overall, occlusal, and axial surfaces. One-way ANOVA followed by post hoc Tukey's comparison tests was used to analyze the data (α = 0.05).

RESULTS

Significant differences were observed among the resin-based crown materials for trueness (RMS), precision deviation, and internal fit (p < 0.001). AM-F had the lowest intaglio RMS value. Margin RMS values for AM-F and AM-S were significantly lower than those for SM-C and SM-S (p < 0.001). SM-C and SM-S showed superior occlusal fit compared to AM-F and AM-S (p < 0.001).

CONCLUSIONS

The type of CAD-CAM manufacturing method-additive or subtractive-significantly influenced the trueness and internal fit of resin-based definitive crowns.

Additively manufactured resin-based endocrowns: Effect of material type, margin configuration, and pulp chamber depth on fabrication trueness and fit

OBJECTIVE

To evaluate the effects of margin configuration and pulp chamber depth on the fabrication trueness and internal fit of resin-based endocrowns fabricated with additive (AM) and subtractive manufacturing (SM).

METHODS

Four mandibular first molar typodonts prepared with butt joint or 1 mm-wide shoulder margins and 2 mm or 4 mm pulp chamber depths were digitized to design reference endocrowns. These designs were used to fabricate endocrowns with AM (Crowntec [AM-CT], FREEPRINT Crown [AM-FP], Tera Harz TC80DP [AM-GR]) or SM (Tetric CAD [SM-TC]) (n = 7). Surface deviations (external, intaglio, and marginal root mean square, RMS) and triple scan protocol (average gap) were used for digital analyses. Data were analyzed with generalized linear models (α = 0.05).

RESULTS

Intaglio RMS was affected by the interaction of all main factors, while all surface deviations were affected by material type-margin configuration interaction. Material type-pulp chamber depth interaction affected intaglio RMS and average gaps, whereas margin configuration-pulp chamber depth interaction affected all outcomes, except intaglio RMS (P ≤ 0.001). AM-GR mostly led to lower intaglio and marginal RMS, while SM-TC mostly led to lower external RMS (P ≤ 0.022). SM-TC endocrowns with 4-mm depth had the highest and AM-GR endocrowns with 4-mm depth mostly had lower average gaps (P ≤ 0.024).

CONCLUSIONS

The interactions among the main factors affected the trueness of the tested endocrowns. However, no clear trend emerged that would highlight any subgroup as having the highest trueness. Most endocrowns demonstrated clinically acceptable internal gaps.

CLINICAL SIGNIFICANCE

Tested additively manufactured resin-based endocrowns had favorable internal adaptation. However, they may require more chairside adjustments on external surfaces compared to tested subtractively manufactured endocrowns.

Effect of manufacturing trinomial and preparation design on the fabrication and fit accuracy of additively and subtractively manufactured resin-based overlay restorations

OBJECTIVE

To evaluate the effect of the manufacturing trinomial (technology, printer, and resin) and preparation design on the fabrication and fit accuracy (trueness and precision) of additively manufactured (AM) resin-based overlays compared to subtractively manufactured (SM) overlays.

METHODS

Six mandibular right first molar typodont teeth were prepared with varying designs: (A) 1 mm occlusal reduction, (B) 1.5 mm occlusal reduction, (C) B + contrabevel finish line, (D) B + chamfer finish line, (E) C + proximal box, and (F) D + proximal box. Overlays were fabricated using AM-IX (tilting stereolithography), AM-VS (digital light processing), or SM-EN and digitized for fabrication (overall, external, intaglio, marginal) and internal fit accuracy analyses. Data were analyzed with two-way analysis of variance and Bonferroni-corrected post-hoc tests (α = 0.05).

RESULTS

The interaction between the manufacturing trinomial and preparation design affected fabrication accuracy of overall, external, and intaglio surfaces, and the precision of marginal surface deviations and average gaps (P ≤ 0.034). AM-IX overlays mostly had higher overall, external, and marginal fabrication accuracy, whereas SM-EN overlays mostly had lower accuracy across these surfaces (P ≤ 0.019). Preparation designs A, B, and C mostly led to lower overall, external, and intaglio surface trueness within SM-EN overlays (P ≤ 0.014). AM-IX overlays had the lowest and preparation design E led to the highest gaps (P ≤ 0.023).

CONCLUSIONS

AM overlays fabricated with tilting stereolithography mostly had higher fabrication and fit accuracy. Increased axial preparation improved fabrication trueness but did not consistently enhance fit.

Marginal Discrepancy and Internal Fit of 3D-Printed Versus Milled Laminate Veneers: An In Vitro Study

The clinical success of laminate veneers depends upon their marginal discrepancy (MD) and internal gap (IG). This study aims to compare and evaluate the MD, overall discrepancy (OD), absolute marginal discrepancy (AMD), and IG of 3D-printed (Varseosmile TrinQ and Varseosmile Crown Plus) and computer-aided design and manufacturing (CAD/CAM)-milled (Brilliant Crios) laminate veneers using cone-beam computed tomography (CBCT). Thirty maxillary central incisors were prepared and divided randomly into three groups (n = 10). All teeth were scanned for veneer fabrication: Group PVT teeth with 3D-printed Varseosmile TrinQ, Group PVC teeth with 3D-printed Varseosmile Crown Plus, and Group BCM teeth with Brilliant Crios milled veneers. The specimens with respective veneers were scanned using CBCT, and the sectional images were measured for IG, MD, OD, and AMD. The mean values for MD recorded were 0.27, 0.31, and 0.40 for PVT, PVC, and BCM respectively). The mean values for IG recorded were as follows: PVT group-0.24, PVC group-0.28, and BCM group-0.39, and those for OD were as follows: PVT-0.22, PVC-0.32, and BCM-0.41. Intragroup significance was observed for IG and OD (p = 0.001). Findings revealed that milled veneers have a higher IG and MD than 3D-printed veneers, making them less clinically acceptable.

Comparison of mechanical and surface properties of two 3D printed composite resins for definitive restoration

STATEMENT OF PROBLEM

Additive manufacturing (AM) technology is emerging as an innovative approach in the dental field. In recent years, manufacturers have introduced 3-dimensionally printed composite resins (3D-CRs) that are specifically designed for the AM of definitive prostheses; however, the mechanical and surface properties of these materials require investigation.

PURPOSE

The purpose of this in vitro study was to assess and compare the mechanical and surface properties of 2 commercially available 3D-CRs for definitive restoration after artificial aging.

MATERIAL AND METHODS

Saremco print Crowntec; Saremco Dental AG and Varseo Smile Crown Plus; Bego GmbH were printed with a layer thickness of 50 µm at a 90-degree angle. A total of 20 bar-shaped specimens (25×2×2 mm) were produced from each material to measure the flexural strength (σf) and elastic modulus (E) using a 3-point bend test, and 5 disk-shaped specimens (Ø15×3 mm) from each material were used to measure the surface microhardness using a microhardness test. Half of the specimens were tested under dry conditions, while the other half were immersed in distilled water for 30 days. Five disk-shaped specimens (Ø15×3 mm) from each material were used to evaluate surface roughness before and after undergoing toothbrushing simulations. Additionally, 5 disk-shaped specimens (Ø15×1 mm) were used to assess water sorption (wsp) and solubility (wsl) over 28 days. Statistical analyses were conducted using the Wilcoxon matched-pairs signed-rank test (1-tailed) with 90% power (α=.05).

RESULTS

The mean ±standard deviation flexural strength values were 123.4 ±8.7 MPa for Saremco print Crowntec and 109.9 ±15.8 MPa for Varseo Smile Crown Plus. After aging, these values were 97.5 ±15.2 MPa for Saremco print Crowntec and 94.2 ±11.7 MPa for Varseo Smile Crown Plus. The mean Vickers hardness values were 33.2 ±0.8 N/mm2 for Saremco print Crowntec and 31.5 ±0.6 N/mm2 for Varseo Smile Crown Plus. After aging, the mean values were 31.7 ±0.9 N/mm2 for Saremco print Crowntec and 29.6 ±1.0 N/mm2 for Varseo Smile Crown Plus. The mean modulus of elasticity was 4.2 ±0.3 GPa for Saremco print Crowntec and 3.82 ±0.2 GPa for Varseo Smile Crown Plus. After 21 days, the mean sorption values were 11.52 ±0.6 mg/mm3 for Saremco print Crowntec and 12.43 ±0.4 mg/mm3 for Varseo Smile Crown Plus. After 28 days, the mean solubility values were 1.36 ±0.4 mg/mm3 for Saremco print Crowntec and 0.98 ±0.3 mg/mm3 for Varseo Smile Crown Plus. Significant differences were found between the 2 3D-CRs in flexural strength in the dry state (P=.03), in Young modulus after 30 days of water immersion (P=.023), and in Vickers hardness in the dry state (P=.01) and after 30 days of water immersion (P=.018).

CONCLUSIONS

Both 3D-CRs provided good in vitro performance and the mechanical properties required for long-term clinical application. Artificial aging decreased the flexural strength of both 3D-CRs.

3D-printed intracoronal restorations, occlusal and laminate veneers: Clinical relevance, properties, and behavior compared to milled restorations; a systematic review and meta-analysis

OBJECTIVES

To assess the feasibility of producing 3D-printed intracoronal restorations, thin and ultrathin veneers, and to compare their mechanical behavior, accuracy, biological, and stain susceptibility to the currently applied milled restorations.

MATERIALS AND METHODS

The databases were comprehensively searched for relevant records up to January 2024 without language restrictions. All studies that assessed 3D-printed partial coverage restorations including inlays, onlays, laminate, and occlusal veneers were retrieved.

RESULTS

The web search yielded a total of 1142 records, with 8 additional records added from websites at a later stage. Only 17 records were ultimately included in the review. The included records compared 3D-printed; alumina-based- and zirconia ceramics, lithium disilicate ceramics, polymer infiltrated ceramics, polyetheretherketone (PEEK), resin composites, and acrylic resins to their CNC milled analogs. The pooled data indicated that it is possible to produce ultrathin restorations with a thickness of less than 0.2 mm. 3D-printed laminate veneers and intracoronal restorations exhibited superior trueness, as well as better marginal and internal fit compared to milled restorations (p < 0.05). However, it should be noted that the choice of materials and preparation design may influence these outcomes. In terms of cost, the initial investment and production expenses associated with 3D printing were significantly lower than those of CNC milling technology. Additionally, 3D printing was also shown to be more time-efficient.

CONCLUSIONS

Using additive manufacturing technology to produce restorations with a thickness ranging from 0.1 to 0.2 mm is indeed feasible. The high accuracy of these restorations, contributes to their ability to resist caries progression, surpassing the minimum clinical threshold load of failure by a significant margin and reliable adhesion. However, before 3D-printed resin restorations can be widely adopted for clinical applications, further improvements are needed, particularly in terms of reducing their susceptibility to stains.

CLINICAL SIGNIFICANCE

3D-printed intracoronal restorations and veneers are more time and cost-efficient, more accurate, and could provide a considerable alternative to the currently applied CNC milling. Some limitations still accompany the resin materials, but this could be overcome by further development of the materials and printing technology.

Effect of barium silicate on mechanical properties, transmittance, and protein adsorption of resin for additive manufacturing containing zwitterionic polymer

STATEMENT OF PROBLEM

Studies on the effect of barium silicate on the material properties of additively manufactured (AM) resins containing 2-methacryloyloxyethyl phosphorylcholine (MPC) for dental applications are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the mechanical properties, transmittance, and protein adsorption of MPC-containing AM resin incorporated with different barium silicate contents and to compare these findings with those of a commercially available unfilled AM resin marketed for definitive restorations.

MATERIAL AND METHODS

Resins incorporating 6 wt% MPC and 4 different concentrations of barium silicate (10 wt%, MB10; 20 wt%, MB20; 30 wt%, MB30; and 40 wt%, MB40) were prepared. An MPC-containing resin with no filler was also prepared (0 wt%, MBN). Surface roughness (n=15), Vickers hardness (n=15), flexural strength and modulus (n=15), fracture toughness (n=15), transmittance (n=15), and protein adsorption (n=3) of the filled resin specimens were measured and compared with those of commercially available unfilled resin specimens. All data were analyzed using the Kruskal-Wallis and Dunn tests (α=.05).

RESULTS

All experimental resins had higher surface roughness than the unfilled resin (P≤.048). MB40 had higher hardness, flexural strength, flexural modulus, and fracture toughness than most other groups (P≤.047). MB10 had higher transmittance than most other groups (P≤.012). All experimental resins had lower protein adsorption than the unfilled resin, regardless of the barium silicate content (P≤.023).

CONCLUSIONS

The experimental resin containing 6 wt% MPC and 40 wt% barium silicate showed better mechanical properties and lower protein adsorption than the resin with no MPC or ceramic fillers. Transmittance decreased with the increase of barium silicate in the resins.

Fabrication trueness and marginal quality of additively manufactured resin-based definitive laminate veneers with different restoration thicknesses

OBJECTIVES

To evaluate how restoration thickness (0.5 mm and 0.7 mm) affects the fabrication trueness of additively manufactured definitive resin-based laminate veneers, and to analyze the effect of restoration thickness and margin location on margin quality.

METHODS

Two maxillary central incisors were prepared either for a 0.5 mm- or 0.7 mm-thick laminate veneer. After acquiring the partial-arch scans of each preparation, laminate veneers were designed and stored as reference data. By using these reference data, a total of 30 resin-based laminate veneers were additively manufactured (n = 15 per thickness). All veneers were digitized and stored as test data. The reference and test data were superimposed to calculate the root mean square values at overall, external, intaglio, and marginal surfaces. The margin quality at labial, incisal, mesial, and distal surfaces was evaluated. Fabrication trueness at each surface was analyzed with independent t-tests, while 2-way analysis of variance was used to analyze the effect of thickness and margin location on margin quality (α = 0.05).

RESULTS

Regardless of the evaluated surface, 0.7 mm-thick veneers had lower deviations (P < 0.001). Only the margin location (P < 0.001) affected the margin quality as labial margins had the lowest quality (P < 0.001).

CONCLUSION

Restoration thickness affected the fabrication trueness of resin-based laminate veneers as 0.7 mm-thick veneers had significantly higher trueness. However, restoration thickness did not affect the margin quality and labial margins had the lowest quality.

CLINICAL SIGNIFICANCE

Laminate veneers fabricated by using tested urethane-based acrylic resin may require less adjustment when fabricated in 0.7 mm thickness. However, marginal integrity issues may be encountered at the labial surface.

Mechanical and Material Analysis of 3D-Printed Temporary Materials for Implant Reconstructions-A Pilot Study

In this study, the authors analyzed modern resin materials typically used for temporary reconstructions on implants and manufactured via 3D printing. Three broadly used resins: NextDent Denture 3D, NextDent C&B MFH Bleach, and Graphy TC-80DP were selected for analysis and compared to currently used acrylic materials and ABS-like resin. In order to achieve this, mechanical tests were conducted, starting with the static tensile test PN-EN. After the mechanical tests, analysis of the chemical composition was performed and images of the SEM microstructure were taken. Moreover, numerical simulations were conducted to create numerical models of materials and compare the accuracy with the tensile test. The parameters obtained in the computational environment enabled more than 98% correspondence between numerical and experimental charts, which constitutes an important step towards the further development of numeric methods in dentistry and prosthodontics.