In vitrocolor evaluation of esthetic coatings for metallic dental implants and implant prosthetic appliances

The use of digital technologies in peri-implant soft tissue augmentation - A narrative review on planning, measurements, monitoring and aesthetics

OBJECTIVE

To identify the different uses and modalities of digital technologies to diagnose, plan and monitor peri-implant soft tissue conditions and aesthetics.

METHODS

A comprehensive narrative review of pertinent literature was conducted, critically appraising key digital technologies that may assist peri-implant soft tissue augmentation and assessment. An electronic search on four databases including studies published prior to 1st July 2023 was performed and supplemented by a manual search.

RESULTS

Predominantly, tools such as cone beam computed tomography (CBCT), intraoral scanning (iOS), intraoral ultrasonography and digital spectrophotometry were commonly to assess and monitor peri-implant soft tissues. The main clinical and research applications included: (i) initial assessment of mucosal thickness, supra-crestal tissue height and keratinized mucosa width, (ii) evaluation of peri-implant soft tissue health and inflammation, (iii) monitoring profilometric changes and midfacial mucosal margin stability over time and (iv) aesthetic evaluation through colour assessment. While evidence for some digital tools may be limited, the integration of digital technologies into peri-implant soft tissue management holds great promise. These technologies offer improved precision, comfort and speed in assessment, benefiting both patients and clinicians.

CONCLUSION

As digital technologies progress, their full potential in peri-implant soft tissue augmentation and their value will become more evident with ongoing research. Embracing these innovations and their potential benefits is recommended to ensure that during progress in implant dentistry, patient care is not hindered.

The clinical use of computer aided designed/computer aided manufactured titanium nitride coated implant abutments: Surgical and prosthetic considerations-A case series

OBJECTIVE

To describe the clinical use of nitride-coated titanium CAD/CAM implant abutments in the maxillary esthetic zone in two patients with high esthetic and functional demands and, to highlight the advantages of nitride-coated milled titanium abutments when compared to stock/custom titanium, one-piece monolithic zirconia, and hybrid metal-zirconia implant abutments.

CLINICAL CONSIDERATIONS

Due to the inherent mechanical and esthetic clinical challenges, single implant-supported reconstructions in the maxillary esthetic zone are a complex restorative treatment. While CAD/CAM technology has been suggested to enhance and ease implant abutment design and manufacturing, implant abutment material selection remains as a critical decision affecting restoration's long-term clinical outcomes. To date, considering the esthetic disadvantages of conventional titanium implant abutments, the mechanical limitations of one-piece zirconia abutments and the manufacturing time and costs associated with hybrid metal-zirconia abutments, no abutment material can be considered "ideal" for all clinical scenarios. Due to their biocompatibility, biomechanical characteristics (hardness and wear resistance), optical properties (yellow color), and peri-implant soft tissue esthetic integration, the use of CAD/CAM titanium nitride-coated implant abutments has been suggested as a predictable implant abutment material in mechanically challenging but esthetically demanding clinical situations, as the maxillary esthetic zone.

CONCLUSIONS

Two patients requiring a combined tooth-implant restorative treatment in the maxillary esthetic zone were treated using CAD/CAM nitride coated titanium implant abutments. The principal advantages of TiN coated abutments include comparable clinical outcomes to stock abutments, optimal biocompatibility, adequate fracture, wear, and corrosion resistance, reduced bacterial adhesion, and excellent esthetic integration with adjacent soft tissues.

CLINICAL SIGNIFICANCE

Clinical reports and short term mechanical, biological and esthetic clinical outcomes indicate that CAD/CAM nitride coated titanium implant abutments can represent a predictable restorative alternative to stock/custom and metal/zirconia implant abutments and be considered a clinical relevant option in mechanically challenging but esthetically demanding situations, as often found in the maxillary esthetic zone.

Evaluation of the effect of anodization-colored titanium abutments and zirconia substructure thickness on zirconia substructure color: An In vitro study

BACKGROUND AND AIM

The aim of this study is to evaluate the effect of anodized titanium abutments and zirconia substructure thickness on the color of zirconia substructure.

MATERIALS AND METHODS

In this study, an electrochemical anodization setup was prepared for titanium coloring. Commercial titanium, anodization-colored yellow and pink titanium, and zirconia were used as different abutment specimens. Thirty zirconia discs in 0.7, 0.9, and 1.1 mm thickness were prepared from zirconia blocks as zirconia substructure specimens (n = 10). Zirconia substructure specimens of different thicknesses were placed on abutment specimens of different colors and L*, a*, b* values were measured with a spectrophotometer device. Color difference (ΔE) was calculated according to the CIELab formula by comparing the L*, a*, and b* values obtained on the zirconia abutment with the L*, a*, and b* values obtained on the other abutments. Statistical analyzes were performed with two-way analysis of variance and Tukey Honestly Significant Difference (HSD)test (p < 0.05).

RESULTS

The increase in the thickness of the substructure resulted in a statistically significant difference on ΔE, L*, a*, and b* values (p < 0.001). The effect of abutment color had no significant effect on ΔE values. The highest ΔE value was 18.10 at zirconia substructure with 0.7 mm thickness when paired with pink-anodized titanium abutment specimens.

CONCLUSION

The thickness of zirconia substructure and the color of titanium abutments affect zirconia substructure color.

Titanium Nitride Coated Implant Abutments: From Technical Aspects And Soft tissue Biocompatibility to Clinical Applications. A Literature Review

PURPOSE

To review the most up to date scientific evidence concerning the technical implications, soft tissue biocompatibility, and clinical applications derived from the use of titanium nitride hard thin film coatings on titanium alloy implant abutments.

MATERIALS AND METHODS

A review was performed to answer the following focused question: "What is the clinical reliability of nitride coated titanium alloy abutments?". A MEDLINE search between 1980 and 2021 was performed for investigations pertaining to the clinical use of nitride coated titanium alloy implant abutments (TiN) in case reports, case series, and short- and long-term non/randomized controlled clinical trials. Literature analysis led to addition evaluation of research related to the technical and biological aspects, as well as the physicochemical characteristics of TiN hard thin film coatings and their impact on titanium abutment biocompatibility, mechanical properties, macroscopic surface topography, and optical properties. Therefore, preclinical data from biomechanical and in vitro investigations were also considered as inclusion criteria.

RESULTS

The limited number of clinical investigations published made a systematic review and meta-analysis not possible, therefore a narrative review was conducted. TiN coatings have been applied to dental materials and instruments to improve their clinical longevity. Implant abutments are coated with titanium nitride to mask the titanium oxide surface and enhance its surface characteristics providing the TiN abutment surface with a low friction coefficient and a very high chemical inertness. TiN coating is suggested to reduce early bacterial colonization and biofilm formation and enhance fibroblast cell proliferation, attachment and adhesion when compared to Ti controls. Additionally, studies indicate that hard thin film coatings enhance the mechanical properties (hardness and wear resistance) of titanium alloy and appears as a yellow color when deposited on the titanium alloy substrate. To date, clinical investigations show that nitride coated titanium abutments provide promising short-term clinical outcomes.

CONCLUSIONS

Published research on nitride-coated abutments is still limited, however, the available biomedical research, mechanical engineering tests, in vitro investigations, and short-term clinical trials have, to date, reported promising mechanical, biological, and esthetic outcomes.

An esthetic evaluation of different abutment materials in the anterior Maxilla: A randomized controlled clinical trial using a crossover design

PURPOSE

To assess the effect of implant abutment material and soft tissue thickness on the peri-implant soft tissue color using spectrophotometry and to evaluate gingival esthetics and patient satisfaction with three different abutments.

MATERIALS AND METHODS

Twenty-five patients with a missing maxillary tooth in the esthetic area received an endosseous implant using a two-stage protocol. Grey titanium, pink anodized titanium, and hybrid zirconia custom abutments were fabricated for each participant and inserted for one week with a cross-over design in a randomized manner. Color measurements were made using a spectrophotometer comparing midfacial peri-implant soft tissue and marginal gingiva of the contralateral tooth. CIE Lab color scale was employed following the formula: ΔE = [(∆L)² +(∆a)² +(∆b)² ] ^½ . PES scores were recorded, and patient satisfaction questionnaires were completed at each abutment change visit and at 1-year follow-up. Statistical analysis was performed using Friedman's test and the Wilcoxon signed-rank test with Bonferroni correction as well as the Mann-Whitney U test (α = 0.05).

RESULTS

Abutment material type significantly affected the ΔΕ values of the peri-implant mucosa when compared to the contralateral teeth. At baseline, the highest ΔΕ means ± standard deviation (SD) values were obtained with grey titanium (11.25 ±2.98), followed by pink anodized titanium (9.90 ±2.51), and zirconia abutments (6.46 ±1.43). Differences were statistically significant irrespective of soft tissue thickness. The highest PES values were obtained with zirconia abutments (10.88 ±0.88), followed by pink anodized titanium (10.12 ±1.13) and the lowest with grey titanium (9.68 ±1.41). PES differences were significant only for the thin soft tissue group. Regarding patient satisfaction, VAS scores for the pink anodized and zirconia hybrid abutment groups were higher than the grey titanium group for each question.

CONCLUSION

The color difference between soft tissues around teeth and implants was significant in all groups regardless of tissue thickness. The hybrid zirconia abutments resulted in the least color difference, followed by pink anodized and grey titanium. Significantly different PES values were recorded only for the thin tissue group. There was no significant difference in patient satisfaction between zirconia and pink anodized abutments at the 1-year follow up. Pink anodized abutments represent a good esthetic alternative to zirconia hybrid abutments especially in mechanically challenging situations. This article is protected by copyright. All rights reserved.

Influence of anodized titanium abutments on the esthetics of the peri-implant soft tissue: A clinical study

STATEMENT OF PROBLEM

The grayish appearance of a titanium abutment discolors the peri-implant soft tissue, especially if the gingiva is thin. Whether an anodized titanium abutment can prevent the discoloration is unclear.

PURPOSE

The purpose of this clinical study was to investigate the color change of peri-implant soft tissue surrounding a titanium abutment that had been colored by anodic oxidation.

MATERIAL AND METHODS

Commercially available titanium abutments were anodized to form a gold and pink titanium abutment and formed the experimental groups. Unanodized titanium and zirconia abutment were used as the control groups. Four types of abutments were fabricated for each participant who received dental implants in the anterior maxilla. The abutments and corresponding definitive crowns were inserted, and the color of the peri-implant soft tissue and contralateral gingiva were measured with a spectrophotometer. The thickness of the peri-implant soft tissue was recorded after probing with an endodontic file.

RESULTS

Eleven participants were included in this study. The color differences caused by all tested abutments were higher than the critical threshold of ΔE=3.7. The mean color difference (ΔE), from low to high, was the zirconia, pink-anodized titanium, gold-anodized titanium, and unanodized titanium abutment; their values of (ΔE) were 6.81, 7.63, 7.90, and 8.74, respectively. The mean thickness of the peri-implant soft tissue was 2.41 ±0.52 mm.

CONCLUSIONS

Within the limitation of the small sample size in this study, the gold-anodized and pink-anodized titanium abutment achieved better esthetics for peri-implant soft tissue than the unanodized titanium abutment. Zirconia was the optimal abutment material for the esthetic region.

Changes in the esthetic, physical, and biological properties of a titanium alloy abutment treated by anodic oxidation

STATEMENT OF PROBLEM

The grayish appearance of titanium abutments adversely affects peri-implant esthetics in patients with thin mucosa, impacting patient satisfaction with implant-supported restorations in esthetic regions.

PURPOSE

The purpose of this in vitro study was to change the color of titanium alloys with anodic oxidation and to evaluate alterations in the esthetic, physical, and biological properties of the anodized titanium alloys.

MATERIAL AND METHODS

Pink and yellow titanium alloys produced by anodization were the experimental groups, and the untreated titanium alloy and zirconia were used as the control groups. Pig gingiva was placed on the tested specimens to evaluate the esthetic effect by recording the color change in the gingiva. Physical properties including morphology, chemical composition, roughness, and contact angle were evaluated by scanning electron microscopy, atomic force microscopy, and a contact angle analysis system. Biological properties were evaluated by observing the cell behaviors of human gingival fibroblasts, using scanning electron microscopy, fluorescence microscopy, a live/dead viability assay, and a cell counting assay.

RESULTS

A variety of colors can be produced on the surfaces of titanium alloys by anodization at different voltages. Titanium alloys anodized at 60 and 65 V exhibited yellow and pink appearances, respectively. Color differences of gingiva caused by anodized titanium alloys were lower than those of the untreated titanium alloy, but they were higher than those of zirconia. Compared with the untreated titanium alloy, the anodized titanium alloys exhibited grain formation, a lower contact angle, and higher roughness. Cell morphology, proliferation, and viability on surfaces of anodized titanium alloys were similar to those of the untreated titanium alloy but lower than those of zirconia.

CONCLUSIONS

Anodization could change the color of titanium alloys to pink or yellow at different voltages. Grain formation, roughness, and hydrophilicity were increased after treatment. The esthetics and biocompatibility of anodized titanium alloys were not as good as that of zirconia, but the pink and yellow titanium alloys treated by anodization achieved better gingival esthetics than the untreated titanium alloy.

The Esthetic Effect of Veneered Zirconia Abutments for Single-Tooth Implant Reconstructions: A Randomized Controlled Clinical Trial

PURPOSE

The purposes of this study were to test whether or not veneering of the submucosal part of zirconia abutments can positively influence the esthetic outcome compared with nonveneered zirconia abutments; to evaluate the influence of the mucosal thickness on the esthetic outcomes of the veneered and nonveneered abutments; and to evaluate the thickness of the peri-implant mucosa compared with the thickness of the gingiva of contralateral tooth sites.

MATERIALS AND METHODS

Forty-four single-tooth implants in 44 patients were randomly restored with either cemented (CR) or screw-retained (SR) reconstructions based on white zirconia abutments (CR-W, SR-W) or pink-veneered zirconia abutments (CR-P, SR-P). Esthetic outcome measurements were performed based on a spectrophotometric evaluation of the peri-implant mucosal color. In addition, the thickness of the mucosa was measured. A two-way analysis of variance was conducted to test the effect of veneering (pink vs white) and mucosa thickness (<2 mm vs ≥2 mm) on the calculated color difference ΔE for pooled data of CR and SR reconstructions (p < .05).

RESULTS

Analyses grouping the sites according to veneering of the abutments and mucosal thickness demonstrated less discoloration for sites with a veneered abutment irrespective of the mucosal thickness: ΔE 4.50 ± 1.93 (<2 mm) and ΔE 6.88 ± 2.45 (≥2 mm); CR-P, SR-P) compared with sites without veneering ΔE 9.72 ± 3.82 (<2 mm; CR-W, SR-W) and ΔE 8.31 ± 2.98 (≥2 mm). The differences between veneered and nonveneered abutments were significant (p = .032).

CONCLUSIONS

Veneering of zirconia abutments with pink veneering ceramic positively influenced the peri-implant mucosal color.

Impact of abutment material on peri-implant soft tissue color. An in vitro study

OBJECTIVES

The objectives of the present study is to determine the differences in peri-implant soft tissue color with the utilization of titanium, titanium gold-plated, white zirconia, Vita Classical (VC) A4-shaded zirconia, and fluorescent white zirconia abutments and to establish the influence of gingival thickness on the resulting color.

METHODS

Four implants were contralaterally inserted in 19 fresh pig mandibles, and the color of the peri-implant mucosa with the different abutments was spectrophotometrically measured at 1-, 2-, and 3-mm height from the margin.

RESULTS

At 1-mm height, titanium significantly differed from all zirconia abutments in lightness (L*), chroma along red axis (a*), and chroma along yellow-blue axis (b*) parameters. At 2 mm, all zirconia abutments differed from titanium in b* but only fluorescent zirconia in a*. At 3 mm, titanium differed from VC A4-shaded and fluorescent zirconia abutments in b*. At soft tissue thicknesses <1 and 1-2 mm, titanium differed from fluorescent zirconia in a* and b* and from VC A4-shaded zirconia in b*; at thickness >2 mm, no differences were found among abutments. All abutments differed from natural teeth in a* and b* at all heights and thicknesses except for fluorescent zirconia at thickness >2 mm. The Euclidean distance (ΔΕ) differed between titanium abutments and gold, VC A4, and fluorescent zirconia at <1- and 1-2-mm thicknesses.

CONCLUSION

The natural gingival color was not reproduced with any abutment at gingival thicknesses <2 mm. The worst color match was with titanium abutments and the best with fluorescent zirconia, followed by VC A4-shaded zirconia. At gingival thicknesses >2 mm, no differences were detected among abutments.

CLINICAL RELEVANCE

This study demonstrates that the type of abutment and the gingival thickness affect the resulting peri-implant gingival color.

Discoloration of the mucosa caused by different restorative materials - a spectrophotometric in vitro study

OBJECTIVES

To evaluate the discoloration of the mucosa caused by different ceramic and metal-based materials.

MATERIAL AND METHODS

On six pig maxillae, trap-door flaps were prepared bilaterally. Different ceramic and metal-based specimens were placed underneath the flap. To simulate increasing mucosal thicknesses (MC), connective tissue grafts (CTGs) were harvested. Spectrophotometric measurements were performed prior to flap elevation (T_BL ) and for each material under the flap alone (1 mm MC) (T_MC1 ), with a 1-mm CTG (2-mm MC) (T_MC2 ) and with a 2-mm CTG (3-mm MC) (T_MC3 ). Tested materials were as follows: Zr1 (zirconia), Zr2 (zirconia + pink ceramic), Zr3 (zirconia), Zr4 (fluorescent zirconia), Zr5 (zirconia), Zr6 (high translucent zirconia), Zr7 (low translucent zirconia) and Zr8 (low translucent zirconia), Gol (gold alloy), Ti1 (titanium alloy), Ti2 (anodized gold-shaded titanium alloy) and Ti3 (anodized pink-shaded titanium alloy). Color differences (ΔE) were calculated comparing the measurement of the native tissue (T_BL ) and the measurements with varying mucosal thicknesses (T_MC1-3 ).

RESULTS

For ceramic materials, the median ΔE values for the different time-point comparison ranged as follows: 3.80 (Zr4) - 7.47 (Zr2) (pooled); 3.15 (Zr4) - 8.13 (Zr2) (T_BL -T_MC1 ); 3.39 (Zr4) - 7.24 (Zr2) (T_BL -T_MC2 ); 4.31 (Zr8) - 6.99 (Zr2) (T_BL -T_MC3 ). For metal-based materials, the median ΔE values were as follows: 4.20 (Gol) - 5.82 (Ti3) (pooled); 3.21 (Gol) - 13.56 (Ti1) (T_BL -T_CM1 ); 4.0 (Ti1) - 5.27 (Gol) (T_BL -T_CM2 ); 3.11 (Ti1) - 5.11 (Gol) (T_BL -T_CM2 ). The comparison of the materials and the time points showed in the nonparametric linear mixed model a significant interaction effect between material and time point (P < 0.001). The side was not a significant main effect, nor as term in an interaction with the other two effects.

CONCLUSIONS

Reconstructive materials result in an evident discoloration of the mucosal tissue, tending to decrease with increasing mucosal thickness. The use of fluorescent zirconia (ceramic materials) or gold alloy (metal-based materials) lead to the least discoloration.

Spectrophotometric and visual evaluation of peri-implant soft tissue color

AIM

To spectrophotometrically and visually test whether the peri-implant mucosal color differs from the color of the natural gingiva.

MATERIAL AND METHODS

Forty single implants in the incisor and premolar region of 40 patients were assessed 3-7 years after implant placement. The differences of the color components lightness, chroma along red-green axis, chroma along yellow-blue axis, and the total color difference ΔE between peri-implant mucosa and natural gingiva were measured with a spectrophotometer. The color difference between peri-implant mucosa and natural gingiva was visually evaluated by clinicians and rated as "clinically visible" or "clinically invisible" from speaking distance. The dimensions of peri-implant mucosa and gingiva at the mid-buccal aspect were evaluated by using cone-beam CT. Spearman analysis was performed to detect correlations between different variables. Two-sided t-test, ANOVA, Mann-Whitney, and Kruskal-Wallis tests were applied to detect differences between the groups.

RESULTS

The spectrophotometrically assessed color difference ΔE between peri-implant mucosa and natural gingiva amounted to 7.0 ± 3.9. The peri-implant mucosa presented a significant dark, greenish and bluish discoloration in comparison with gingiva at control teeth. Clinical investigation revealed that in 60% of sites the color difference between peri-implant mucosa and natural gingiva was clinically visible from speaking distance. The threshold value ΔE for the extraoral clinical distinction of mucosal color differences measured 7.5. When comparing the groups with visible and invisible color differences with respect to the three color components, a significant difference was found only for chroma along yellow-blue axis. In the group with visible color difference, mucosa presented a bluish discoloration. Correlation analysis indicated that with an increase in mucosal thickness, a trend for smaller ΔE was found.

CONCLUSION

The spectrophotometrically assessed color of the peri-implant mucosa revealed more dark, green and blue components compared to the natural gingiva. At 60% of the implants, peri-implant mucosal discoloration was visible from speaking distance. The sites with visible and those with invisible mucosal discolorations differed significantly only regarding the chroma along yellow-blue axis.

Laboratory technique for coloring titanium abutments to improve esthetics

Titanium alloys are used for implant abutments onto which prostheses are attached. One major disadvantage of titanium abutments is their esthetics; the metallic gray color may show through the restorative material or through surrounding tissues. A laboratory technique using readily available household items is described that can alter the abutment color by anodization.

Color evaluation of a dielectric mirror coating using porcine tissue and prosthetic gingival material: a comparison of two models

AIM

The aim of this study was to firstly evaluate the esthetics of a dielectric multilayer coating on titanium below porcine tissue (in vitro porcine model). Secondly, a polymer model was used to investigate the same samples to compare the models to each other and discuss their validity for optical assessment of esthetic coatings for implant applications.

MATERIALS & METHODS

A dielectric mirror coating was deposited on titanium substrates (Ti- Bragg) and tested below porcine tissue and polymer platelets of three test thicknesses (1 mm, 2 mm and 3 mm). Titanium without coating (Ti) was used as a negative control. Furthermore, the substrates were subjected to three different surface treatments (polished, machined and sand-blasted). The color difference values ΔL, Δa, Δb and ΔE were calculated for each sample. In total, six samples were tested in both models. Statistical analysis of the data (one sample Wilcoxon test, Kruskal-Wallis with Bonferroni-Holm corrected Mann-Whitney post hoc tests for multiple testing) was conducted for each sample in both evaluation methods.

RESULTS

In the in vitro porcine model, sand-blasted Ti-Bragg and Ti samples showed ΔE values significantly above the threshold value of 3.70, indicating a dark appearance of the 1 mm thick covering tissue. As the test thickness increased, polished and machined Ti-Bragg samples were significantly invisible (ΔE < 3.70 with P < 0.05). Excessive brightening effects from Ti-Bragg samples were not observed from the in vitro porcine model, but below polymer platelets the samples exhibited significantly high ΔL values, which also resulted in a significant and visible color change (ΔE >> 3.70 with P < 0.05).

CONCLUSION

Ti-Bragg was suggested to be an appropriate coating system for dental implants to improve the soft tissue esthetics. The design of this coating system can be adjusted by varying different parameters to satisfy the requirements of an esthetic coating. The polymer model is valid for test thicknesses of 2 and 3 mm, however, one might have to increase the thickness to 1.5 mm or alter the composition of the resin for 1 mm thick platelets to increase the opacity and therefore adapt to the soft tissue situation.