Spectrophotometric assessment of peri-implant mucosa after restoration with zirconia abutments veneered with fluorescent ceramic: a controlled, retrospective clinical study

Fifteen ceramic gingival samples: A proposed gingival shade guide

OBJECTIVE

(1) To put forward a set of valid pink ceramic samples for subjective gingival colour selection in the Caucasian population, and (2) to assess the quality of the shade matches provided by the selected pink samples.

METHODS

The ceramic gingival shade samples (n = 133) were obtained by mixing pairs of basic colours from a single system. In each mixture, the proportions of the colours were altered in 10% increments, following the numerical order used by the manufacturers of the three colour systems under study (Heraceram, Vita VM9 and IPS Style). The CIELAB colour coordinates were recorded using spectrophotometry in three zones of healthy anterior gingiva (n = 360). The sample was randomly divided into two subsamples, each of which contained 180 participants. Subsample 1 was used to select the ceramic gingival samples that provided the best shade matches, using the k-means clustering method. Subsample 2 was used to assess the chromatic validity of the selected gingival samples, according to the coverage error.

RESULTS

To identify the ceramic gingival samples that best represented participants' gingival colour, the minimum colour differences (ΔEab∗, ΔE00) between the cluster centroids and the 133 gingival samples were calculated. Fifteen gingival samples were selected: 8 from the Heraceram system, 4 from the VM9 system, and 3 from the IPS Style system. Coverage errors for the 15 gingival samples fell below the gingival clinical acceptability thresholds in the three gingival zones examined.

CONCLUSIONS

The 15 ceramic gingival colour samples provide satisfactory coverage of the gingival colour space, with coverage errors below the ΔE00 clinical acceptability threshold of 2.9 units. These pink colour samples have the potential to provide good gingival shade matches in subjective colour selection.

CLINICAL SIGNIFICANCE

Mixing basic ceramic colours is a viable method for generating a series of pink shades that can be used as a physical gingival shade guide. The resulting guide provides valid results (under the acceptability thresholds) for subjective selection gingival colour selection in clinical practice.

Degree of Standardisation in Ceramic Gingival Systems

No gingival shade guide exists that can be used as a 'gold standard' in gingival shade selection. This research, therefore, aimed to determine whether comparable results in subjective gingival shade selection can be achieved using basic gingival colours produced by distinct manufacturers. It also aimed to explore how coverage of the colour space is affected by mixing these basic colours to create additional shades. To achieve these objectives, the basic gingival colours of three ceramic systems (Heraceram, Kulzer, Madrid, Spain; Vita VM9, Vita Zahnfabrik, Bad Säckingen, Germany; IPS Style, Ivoclar, Schaan, Liechtenstein) were analysed. The colour systems were expanded by creating porcelain gingival samples, whose colours were obtained by mixing the basic colours, altering each mixture by increments of 10%, and respecting the numerical order used by manufacturers to identify the colours. The colour coordinates of the basic and additional colours were recorded using spectrophotometry, and the intra- and inter-system colour differences were calculated using the Euclidean (ΔEab) and CIEDE2000 (ΔE00) formulae. None of the basic colours in the three systems, despite their similar nomenclature, were found to be interchangeable (the colour differences exceeded the gingival acceptability threshold: ΔE00 2.9 units). The expanded gingival colour systems, with mixtures altered by 10% increments, notably increased the gingival colour space covered by the original systems. The authors concluded that there are clear differences between the basic gingival colours produced by distinct manufacturers using the same nomenclature. Ceramic samples produced by mixing basic gingival colours are a resource with the potential to improve subjective gingival shade matching.

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.

Prosthetic failures in dental implant therapy

Both fixed and removable implant‐supported prostheses are well‐established methods for replacing missing teeth in partially or fully edentulous patients. Numerous systematic reviews have been performed in recent years to evaluate the survival and complication rates of implant‐retained fixed dental prostheses and implant‐retained overdentures, displaying high 5‐year survival rates ranging from 97.1% for fixed dental prostheses to 95%‐100% for implant‐retained overdentures. However, the survival rates only represent the prostheses remaining in use for a defined follow‐up time, and do not account for the potential prosthetic complications that may have arisen and influence the general success of the implant treatment. The most common technical complications of fixed implant‐retained single crowns are crown fracture, fractures of ceramic implant abutments, and esthetic problems. The predominant technical complication at multiple‐unit, implant‐retained fixed dental prostheses is fracture/chipping of the veneering ceramic. Reported technical complications for implant‐retained overdentures are overdenture fracture or chipping of the veneer materials, whereas mechanical complications include implant fracture, attachment failure, and attachment housing or insert complications. To reduce the risk of such failures, a comprehensive pretreatment diagnostic work‐up is essential, including defining the prosthetic goal with the aid of a wax‐up or set‐up and the associated ideal, prosthetically oriented three‐dimensional implant position. Furthermore, selection of the ideal type of prosthesis, including the respective implant components and materials, is important for clinical long‐term treatment success.

Peri-implant soft-tissue esthetic outcome after immediate implant placement in conjunction with xenogeneic acellular dermal matrix or connective tissue graft: A randomized controlled clinical study

OBJECTIVES

This randomized comparative study evaluated the clinical esthetic outcome of the peri-implant mucosa following extraction and immediate implant placement in conjunction with anorganic bovine bone mineral (ABBM) and the use of a porcine acellular dermal matrix (pADM) versus an autogenous connective tissue graft (CTG) in the anterior maxilla.

MATERIALS AND METHODS

Twenty patients (11 men, 9 women) with a mean age of 48,9 years (range 21-72) were included in the study and randomly assigned to either the test (pADM) or control group (CTG). They underwent extraction and immediate implant placement together with ABBM for socket grafting and either pADM or CTG for soft tissue augmentation. Twelve months after implant placement color measurements of the peri-implant mucosa and a reference tooth were performed using a spectophotometer and the color difference (ΔE) was calculated. The overall esthetic appearance of the peri-implant soft tissue was evaluated using the Pink Esthetic Score (PES). Statistical analysis was performed using Student's T-Test, the alpha was set to 0.05.

RESULTS

All implants received osseointegration and were restored. The mean color difference of the peri-implant mucosa 1 year after surgery amounted ΔE 4.06 ± 1.6 for the test group (pADM) and ΔE 3.58 ± 1.36 mm for the control group (CTG), showing no statistically significant difference (p = 0.47). The mean PES of the pADM group was 11.4 ± 1.4 and for the CTG group 10.7 ± 1.5, showing no statistically significant difference (p = 0.29).

CONCLUSION

Twelve months after surgery, a porcine acellular dermal matrix for soft tissue augmentation in conjunction with immediate implant placement showed no difference in the overall esthetic appearance regarding color match and Pink Esthetic Score in comparison to autogenous soft tissue graft.

CLINICAL SIGNIFICANCE

Connective tissue grafts have become a standard in order to enhance the soft tissue quality and esthetic appearance in immediate implant placement. The use of new biomaterials like porcine acellular dermal matrices may avoid the need to harvest autogenous grafts resulting in simplified treatment and less postoperative morbidity.

Effect of anodized titanium abutment collars on peri-implant soft tissue: A split-mouth clinical study

STATEMENT OF PROBLEM

Anodic oxidation of titanium implant abutment collars has been used to mask their unesthetic grayish color. However, the effect of anodic oxidation on the health and appearance of peri-implant soft tissues is unclear.

PURPOSE

The purpose of this split-mouth clinical study was to investigate the effect of anodized titanium on the health and esthetics of peri-implant soft tissues.

MATERIAL AND METHODS

A total of 60 osseointegrated implants placed in 30 participants were included in the present study. Each participant received 2 randomly allocated abutments, one with a pink anodized collar and the other with an unanodized one to form 2 groups: unanodized group (control group) and anodized group (experimental group). All implants were restored with lithium disilicate restorations. Evaluations of the peri-implant soft tissues were performed at the time of definitive restoration insertion (baseline) and after 3, 6, 12, and 18 months: peri-implant probing depth, soft tissue recession, modified sulcus bleeding index, modified plaque index, and modified gingival index. The esthetics of peri-implant soft tissues were evaluated by using the modified pink esthetic score. The paired t test or Wilcoxon signed-rank test was used for comparing the 2 study groups at each point of time depending on the normality of the variables (α=.05). To compare each variable at different time points within each group separately, repeated measures ANOVA or Friedman tests were used according to the normality of the variables, followed by post hoc pairwise comparisons by using the Bonferroni adjusted significance (α=.05).

RESULTS

Five peri-implant soft tissue indices were followed up throughout the study. No statistically significant differences were found among the mean values of the tested indices in the anodized and unanodized groups throughout the evaluation periods (P>.05). The collective mean values of the modified pink esthetic score also showed no statistically significant differences between the groups (P>.05).

CONCLUSIONS

Based on this split-mouth clinical study, pink anodized titanium abutment collars do not produce a clinically significant effect on the health or esthetics of peri-implant soft tissues.

Esthetic, mechanical, and biological outcomes of various implant abutments for single-tooth replacement in the anterior region: a systematic review of the literature

Background

The choice of the appropriate implant abutment is a critical step for a successful outcome. Titanium abutments have demonstrated high survival rates, due to their excellent biocompatibility and high mechanical strength, although they often result in a grayish discoloration of the peri-implant mucosa. This esthetic concern culminated in the introduction of ceramic abutments. The aim of this review was to assess the esthetic, mechanical, and biological outcomes as well as the survival of the different types of abutments used for single-implant restorations in the anterior area.

Material and methods

An electronic search was conducted in Medline, Embase, and Cochrane Central databases using the appropriate Mesh terms and predetermined eligibility criteria. The quality of the studies was assessed using the ROB 2 tool. The last search was conducted on 18th of March 2020.

Results

From the 2074 records initially identified, 23 randomized controlled trials (32 publications) were included for qualitative analysis. Data were classified based on study information, specific characteristics of the intervention and comparator, and information related to the outcome measures. Seven studies exhibited an overall low risk of bias, while twelve studies raised some concerns.

Conclusions

The rate of abutment failure was low and was associated with the ceramic abutments, especially those with internal connection. Limited correlation was noted between soft tissue thickness and color difference. Titanium abutments caused significantly more discoloration to the soft tissues than ceramic abutments, while hueing (gold or pink) slightly improved their color performance. Zirconia allowed a better color match than titanium or gold abutments, still discolored slightly the soft tissues. The submucosally modified zirconia abutments exhibited encouraging results. No significant difference was reported between materials or different types of retention on recession, papillary fill, and biological outcomes.

Dental student, dentist, dental assistant, and layperson perception of pink gingival porcelain color

STATEMENT OF PROBLEM

How pink gingival porcelain color is perceived by participants classified according to profession and sex is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the degree of correlation between the ordering of color tabs by participants classified according to profession, years of dental work experience, and sex and the ideal chromatic order based on the color coordinate L∗ (lightness).

MATERIAL AND METHODS

Twenty-one colored specimens made of Heraceram pink gingival porcelain were used. A group of 352 participants (118 men and 234 women) comprised of dental students (n=126), dentists (n=54), dental assistants (n=56), and laypersons (n=116) were enrolled. They were asked to order the specimens starting from the lightest to the darkest. The Kendall coefficients of concordance W and correlation T were used to determine whether the individuals in each experimental group rating the specimens were consistent and accurate.

RESULTS

The degree of agreement between the ideal ordering and that carried out by the participants within the different professional categories was greater than 0.8 in all assessments. No statistically significant differences were found among the groups in relation to professional category, work experience, or sex (P>.05). The Kendall coefficients were higher in the ranking of the darker specimens for all groups of participants.

CONCLUSIONS

No statistically significant differences were found among dentists, dental assistants, dental students, and laypersons in the arrangement of pink porcelain specimens according to their lightness. In addition, in all groups, the darker gingival specimens were ordered significantly better according to their lightness than the lighter specimens.

The reproducibility of electronic color measurements of the marginal gingiva

INTRODUCTION

This study evaluated the reproducibility of electronic color determination system evaluations of the marginal gingiva, which could be important for adhesive cervical fillings or prosthetic restorations that imitate the gingiva.

MATERIAL AND METHODS

In 50 subjects, the L*, a*, and b* color coordinates were evaluated five times at a point in the marginal area of a central incisor using different electronic color determination systems: (SP) Shadepilot, (ES) Easyshade, (CE) Crystaleye, and (SV) X-Rite. The mean color difference (ΔE) and its standard deviation between the five measurements from each participant were calculated separately for each device. Further ICC for interdevice reliability was determined.

RESULTS

The L*, a*, and b* color coordinates and ΔE values differed significantly among the systems (p < 0.001). Within each patient and measurement system, ΔE ranged from 1.4 to 3.2 (SD 1.1-2.5), L* from 2.6 to 5.7 (SD 2.6-5.7), a* from 11.9 to 21.3 (SD 3.6-3.9), and b* from 15.1 to 28.9 (SD 1.7-4.3). Interdevice reliability ranged between 0.675 and 0.807.

CONCLUSIONS

Color determination of the marginal gingiva using the electronic tooth color determination systems tested herein showed limited reproducibility. The results obtained with the different measurement systems differed enormously.

CLINICAL RELEVANCE

These results show that the electronic color measurement devices tested allow no high reproducible determination of color coordinates of the marginal gingiva.

Zirconia abutments in the anterior region: A systematic review of mechanical and esthetic outcomes

STATEMENT OF PROBLEM

The success of single, anterior, implant-supported restorations relies on mechanical and esthetic outcomes. Titanium has been the most commonly used material for abutments, but zirconia is increasingly chosen for its appearance despite its unclear mechanical performance. Today, manufacturers market prefabricated, computer-aided design and computer-aided manufacturing (CAD-CAM) custom and zirconia abutments with titanium connections.

PURPOSE

The purpose of this study was to systematically review the mechanical and esthetic outcomes of implant zirconia abutments used in the anterior region, considering the design changes of the past 5 years.

MATERIAL AND METHODS

An electronic search was conducted in Medline (PubMed) for studies on zirconia abutments. All clinical studies with at least a 1-year follow-up and case series (>5 abutments) published after 2013 were included. Mechanical and esthetic outcomes were collected.

RESULTS

Of the 231 retrieved studies, 20 remained for quantitative analysis. Twelve described mechanical outcomes, and 15 focused on esthetics, using mainly the pink esthetic score. Five articles reported abutment fractures and no chipping. No difference was found between prefabricated and custom abutments or internal and external implant connections regarding fractures or screw loosening. All authors reported "good to excellent" esthetic integration in terms of restorations and soft-tissue color and the presence and height of papillae. The most difficult esthetic parameters to achieve were root convexity, soft-tissue color, and texture and level of mucosa.

CONCLUSIONS

Esthetics remain the major advantage of zirconia abutment when compared with titanium, despite reservations concerning the risk of mechanical complications. Data are lacking for zirconia abutments with titanium inserts, although the prospects for this design are promising.

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.

Clinical study on natural gingival color

The aims of the study were: to describe the gingival color surrounding the upper incisors in three sites in the keratinized gingiva, analyzing the effect of possible factors which modulate (socio-demographic and behavioral) intersubject variability; to study whether the gingiva color is the same in all three locations and to describe intrasubject color differences in the keratinized gingiva band. Using the CIELAB color system, three reference areas (free gingival margin, keratinized gingival body, and birth or upper part of the keratinized gingiva) were studied in 259 individuals, as well as the related socio-demographic factors, oral habits and the chronic intake of medication. Shadepilot™ spectrophotometer was used. Descriptive and inferential statistical analysis was performed. There are statistically significant differences between males and females for coordinates L* and a* in the middle and free gingival margin. For the b* coordinate, there are differences between males and females in the three locations studied (p < 0.05). The minimum and maximum coordinates in which the CIELAB natural gingival space is delimited are L* minima 28.3, L* maximum 65.4, a* minimum 11.1, a* maximum 37.2, b* minimum 6.9, and b* maximum 25.2*. Age, smoking, and the chronic intake of medication had no significant effect on gum color. There are perceptible color differences within the keratinized gingiva band. These chromatic differences must be taken into account if the prosthetic characterization of gingival tissue is to be considered acceptable. There are significant differences between the color coordinates of the three sites studied in the keratinized gingiva of men and women.

Comparison of two color-difference formulas using the Bland-Altman approach based on gingiva color space

The objectives of this study were to determine the relationship between the results provided by the classical CIELab (ΔE_ab*) and the CIEDE2000 (ΔE00) formulas and the gingival color space using the Bland and Altman limits of agreement, to use this relationship to establish the equivalences between the gingival color thresholds of perceptibility of both formulas, and to evaluate whether the relationship between ΔE_ab* and ΔE00 is modified depending on the axis in which the changes occur. The means of the L*, a*, and b* coordinates of the 21 gingiva porcelain samples (Heraceram, Heraeus Kulzer Mitsui Chemical Groups) were used and the differences in color were calculated in 210 pairs of samples using the CIELab (ΔE*ab) and CIEDE2000 (ΔE00) color-difference formulas. The results obtained with these formulas were compared and the limits of agreement after a logarithmic transformation of the data were obtained. The relationship between both formulas was ln ΔE₀₀ = - 0.22 + ln ΔE_ab*. The results obtained with the CIELab formula were between 1.01 (95% confidence interval 0.98-1.03) and 1.54 (95% confidence interval 1.52-1.59) times higher than those obtained with the CIEDE200 formula. In the gingiva color space, the scale factor between the CIEDE2000 and CIELab values changes from 0.63 to 1.02, such that providing an accurate scale factor between both values proves difficult. The pairs with the highest ratio were those where the difference in color was mainly due to changes in lightness, whereas the pairs with the smallest ratio were those where the difference in color was mainly due to changes in the blue-yellow or green-red axes.

Influence of implant location on the clinical outcomes of implant abutments: a systematic review and meta-analysis

Purpose

To compare the failure events and incidence of complications of different abutment materials in anterior and posterior regions. Failure was defined as complete loss of the abutment requiring replacement by a new abutment.

Materials and methods

Electronic searches using PubMed/Medline and Google Scholar complemented with manual searches were performed with specific search terms. Searches were restricted to publications in English between January 2006 and March 2016.

Results

A total of 863 and 1,264 implants were inserted in the anterior and posterior regions, respectively, in a total of 1,529 patients. No titanium abutments failed in anterior or posterior regions. On the other hand, 1.6% of zirconia abutments failed in the anterior region and 1.5% failed in the posterior region. Technical complications occurred mostly in the posterior region and mostly involved zirconia abutment. Meta-analysis was possible only for zirconia-abutment failure, due to considerable heterogeneity of studies and outcome variables. No significant difference in failure rate was found between anterior and posterior zirconia abutments (risk ratio 1.53, 95% CI 0.49–4.77; P=0.47).

Conclusion

This systematic review and meta-analysis showed similar outcomes of different abutment materials when used in anterior and posterior regions in terms of failure events and biological and aesthetic complications. The only significant finding was the increased incidence of technical complications in the posterior region, mostly involving zirconia abutments. Abutment-screw loosening was the most common technical complication.

A Current Perspective on Screw-Retained Single-Implant Restorations: A Review of Pertinent Literature

OBJECTIVE

There is a trend toward increased use of screw-retained single-implant restorations. A comprehensive literature review was undertaken to examine the data related to screw- and cement-retention and to objectively evaluate the innovations in implant dentistry that have led to this resurgence.

OVERVIEW

When comparing the two options, survival and complication rates are similar, bone and soft-tissue levels are comparable, and zirconia offers esthetic advantages for both selections. Zirconia abutments with bonded titanium inserts provide esthetic alternatives to titanium abutments for both choices. Bone- and soft-tissue responses are similar, but residual cement of cement-retained restorations is associated with significant soft- and hard-tissue complications. The potential weakness of ceramic discontinuity of screw-access openings can be lessened by the incorporation of stronger ceramic materials such as zirconia and lithium disilicate. The overriding remaining indication for cement-retained restorations is to compensate for angled implants.

CONCLUSIONS

Screw-retained single-implant crowns should be reconsidered for many clinical situations for the following reasons: Predictable retention and retrievability No potential for the biologic consequences associated with residual cement As with cement-retained restorations, the choice between metal ceramics or all ceramics Only one margin, at the implant/abutment interface A single abutment/crown ceramic margin that can extend gingivally to the implant interface Nearly imperceptible blend of a composite resin in ceramic abutment access openings One component instead of two, which may simplify the restorative process CLINICAL SIGNIFICANCE: Innovations in implant and ceramic technology now give screw-retained prostheses the potential for esthetic, functional, and biologic outcomes that are comparable to those for cement-retained prostheses, while providing the advantages of predictable retrievability and avoidance of residual cement. Angled implants, however, remain a major indication for cement-retained single-implant prostheses. (J Esthet Restor Dent 29:161-171, 2017).

Color variation induced by abutments in the superior anterior maxilla: an in vitro study in the pig gingiva

PURPOSE

The aim of this work is to evaluate different types of materials used for making implant abutments, by means of an in vitro study and a review of the literature, in order to identify the indications for a better choice of an implant-supported restoration in the anterior section.

MATERIALS AND METHODS

5 implant abutments were tested in a random order in the superior anterior maxilla of pig gingiva (n = 8): titanium dioxide (Nobel Biocare); zirconium dioxide, Standard BO shade (Nobel Biocare, Kloten, Switzerland); zirconium dioxide, Light BI shade (Nobel Biocare); zirconium dioxide, Intense A 3.5 shade (Nobel Biocare); and aluminium oxide. Each abutment was tested for 2 mm and 3 mm thickness. To determine color variation, VITA Easyshade Advance spectrophotometer (Vita Zahnfabrik, Bad Sackingen, Germany) was used.

RESULTS

Results showed that the color variation induced by the abutment would be affected by the abutment material and gingival thickness, when the gingival thickness is 2 mm. All materials except zirconium dioxide (Standard shade) caused a visible change of color. Then, as the thickness of the gingiva increased to 3 mm, the color variation was attenuated in a significant manner and became invisible for all types of abutments, except those made of aluminium oxide.

CONCLUSION

Zirconium dioxide is the material causing the lowest color variation at 2 mm and at 3 mm, whereas aluminium oxide causes the highest color variation no matter the thickness.

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.

Measurement of Reduced Gingival Melanosis after Smoking Cessation: A Novel Analysis of Gingival Pigmentation Using Clinical Oral Photographs

Background: Due to moisture and the anatomical complexity of the oral mucosa, it is difficult to measure the extent of gingival melanosis in an optical manner. Therefore, we developed a new quantitative method using clinical oral photographs and compared the extent of gingival melanosis before and after smoking cessation. Methods: A new analysis method, which we named the gingival melanosis record (GMR), is a quantitative analysis method using clinical oral photographs. We obtained 659 clinical photographs from 263 patients from 16 general dental offices in Japan. Standardized measuring sites were automatically spotted on the screen, and the presence of gingival melanosis was determined at the measuring sites. We assessed the validity of the GMR with the previously reported Hedin’s classification using Spearman’s rank correlation and intraclass correlation coefficients. Results: The GMR showed a significant association with Hedin’s classification (p < 0.01, correlation coefficient = 0.94). The GMR also showed excellent reproducibility of the substantial repeated agreement intraclass correlation coefficients (ICC) (1,1) and ICC (2,1), p > 0.61). The longitudinal loss of gingival melanosis was confirmed by a change in the GMR among patients who successfully achieved smoking cessation for a mean of 4.5 years. Conclusion: The GMR is an effective method to assess gingival melanosis. The loss of gingival melanosis after smoking cessation can be objectively confirmed with the use of the GMR.

The effect of zirconia or titanium as abutment material on soft peri-implant tissues: a systematic review and meta-analysis

AIM

The objective of this review was to analyze research with regard to the effect of zirconia or titanium as abutment material on soft peri-implant tissues.

METHODS

Clinical studies were selected via electronic and hand searches in English language journals until December 1, 2014. Only randomized clinical trials (RCTs) and prospective controlled clinical trials (CCTs) showing direct comparison between zirconia (Zr) and titanium (Ti) abutments in the same patient were considered. The outcome measures were (1) soft tissue color, (2) soft tissue recession, (3) peri-implant probing, (4) bleeding on probing, (5) esthetic indexes, (6) patient-reported outcome, (7) marginal bone level, and (8) biological complications.

RESULTS

Nine relevant studies (11 papers) were identified: 4 RCTs and 5 CCTs. Due to heterogeneity in the study design, statistical methods, and reported results, a meta-analysis of the data was feasible only for soft tissue color. The outcome was found to be significantly superior for Zr abutments. For the other outcome measures, a qualitative analysis of the selected articles was performed. The studies did not show any statistically significant differences between Zr and Ti abutments on soft tissue recession, probing depths, bleeding on probing, marginal bone level, and patient-reported outcome. One study reported significantly higher pink esthetic score (PES) scores at Zr implants with Zr abutments, compared to metal implants and Ti abutments.

CONCLUSION

Overall, the research does not support any obvious advantage of Ti or Zr abutments over each other. However, there is a significant tendency in Zr abutments evoking better color response of peri-implant mucosa and superior esthetic outcome measured by PES score.

Factors involved in the spectrophotometric measurement of soft tissue: A clinical study of interrater and intrarater reliability

STATEMENT OF PROBLEM

The reliability of spectrophotometric measurements of gingival color has not been tested.

PURPOSE

The purpose of this study was to evaluate the repeatability and reproducibility of gingival color measurements with a digital spectrophotometer. Measurement error was estimated by determining the interrater agreement and by repeating measurements in different illumination environments with and without contact of the device with the gingiva.

MATERIAL AND METHODS

Two trained examiners measured the gingival shade around 30 central incisors with a spectrophotometer with and without external illumination and with and without contact of the device with the gingiva. Color data obtained (CIELab color coordinates; L*, c*, h*, a*, b*) were analyzed with the intraclass correlation coefficient (ICC) and the Student t test for paired samples.

RESULTS

Mean L*, c*, a*, and b* values differed significantly between measurements made with and without contact of the device with the tissue, but no difference was found in h* values. An ICC of >0.9 was obtained for interrater and intrarater agreements in all cases. Shade measurements did not differ between the presence and absence of stable ambient light.

CONCLUSIONS

The repeatability and reproducibility of soft tissue shade measurements were almost perfect (ICC >0.9) under the examination conditions tested. The measurements were affected by pressure but not by ambient light.

Peri-implant soft tissue colour around titanium and zirconia abutments: a prospective randomized controlled clinical study

OBJECTIVES

To objectively determine the difference in colour between the peri-implant soft tissue at titanium and zirconia abutments.

MATERIALS AND METHODS

Eleven patients, each with two contralaterally inserted osteointegrated dental implants, were included in this study. The implants were restored either with titanium abutments and porcelain-fused-to-metal crowns, or with zirconia abutments and ceramic crowns. Prior and after crown cementation, multi-spectral images of the peri-implant soft tissues and the gingiva of the neighbouring teeth were taken with a colorimeter. The colour parameters L*, a*, b*, c* and the colour differences ΔE were calculated. Descriptive statistics, including non-parametric tests and correlation coefficients, were used for statistical analyses of the data.

RESULTS

Compared to the gingiva of the neighbouring teeth, the peri-implant soft tissue around titanium and zirconia (test group), showed distinguishable ΔE both before and after crown cementation. Colour differences around titanium were statistically significant different (P = 0.01) only at 1 mm prior to crown cementation compared to zirconia. Compared to the gingiva of the neighbouring teeth, statistically significant (P < 0.01) differences were found for all colour parameter, either before or after crown cementation for both abutments; more significant differences were registered for titanium abutments. Tissue thickness correlated positively with c*-values for titanium at 1 mm and 2 mm from the gingival margin.

CONCLUSIONS

Within their limits, the present data indicate that: (i) The peri-implant soft tissue around titanium and zirconia showed colour differences when compared to the soft tissue around natural teeth, and (ii) the peri-implant soft tissue around zirconia demonstrated a better colour match to the soft tissue at natural teeth than titanium.