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

A Novel Prehydrated Porcine-Derived Acellular Dermal Matrix: A Histological and Clinical Evaluation

It is well known that soft tissue quality and quantity around dental implants is of paramount importance for later peri-implant health. For this purpose, the clinical and histological outcomes of the peri-implant mucosa, following soft tissue augmentation for soft tissue improvement with a novel prehydrated porcine acellular dermal matrix graft (PPADMG) in conjunction with simultaneous implant placement, were evaluated in this case series. Twenty-two patients were included in the study. They underwent a late implant placement protocol combined with PPADMG for soft tissue augmentation. A punch biopsy was taken at the time of uncovery of the submerged healed implant after a mean of 157 days healing time. Supracrestal soft tissue height (STH) was measured at the time of implant placement and uncovery. All sites showed a clinical increase in STH. The histological structure of the biopsies resembled a similar structure as found in the healthy oral mucosa. No unexpected tissue reactions could be found. Within the limits of this clinical and histological study, it may be concluded that STH improvement with this novel porcine-derived acellular dermal matrix, in combination with simultaneous implant placement, is a viable option to create a peri-implant tissue thickness and stability.

Influence of nanosecond laser surface patterning on dental 3Y-TZP: Effects on the topography, hydrothermal degradation and cell response

OBJECTIVES

Laser surface micropatterning of dental-grade zirconia (3Y-TZP) was explored with the objective of providing defined linear patterns capable of guiding bone-cell response.

METHODS

A nanosecond (ns-) laser was employed to fabricate microgrooves on the surface of 3Y-TZP discs, yielding three different groove periodicities (i.e., 30, 50 and 100 µm). The resulting topography and surface damage were characterized by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). X-Ray diffraction (XRD) and Raman spectroscopy techniques were employed to assess the hydrothermal degradation resistance of the modified topographies. Preliminary biological studies were conducted to evaluate adhesion (6 h) of human mesenchymal stem cells (hMSC) to the patterns in terms of cell number and morphology. Finally, Staphylococcus aureus adhesion (4 h) to the microgrooves was investigated.

RESULTS

The surface analysis showed grooves of approximately 1.8 µm height that exhibited surface damage in the form of pile-up at the edge of the microgrooves, microcracks and cavities. Accelerated aging tests revealed a slight decrease of the hydrothermal degradation resistance after laser patterning, and the Raman mapping showed the presence of monoclinic phase heterogeneously distributed along the patterned surfaces. An increase of the hMSC area was identified on all the microgrooved surfaces, although only the 50 µm periodicity, which is closer to the cell size, significantly favored cell elongation and alignment along the grooves. A decrease in Staphylococcus aureus adhesion was observed on the investigated micropatterns.

SIGNIFICANCE

The study suggests that linear microgrooves of 50 µm periodicity may help in promoting hMSC adhesion and alignment, while reducing bacterial cell attachment.

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.

Abutment removal torque and implant conical surface morphological changes after standardized artificial aging: An in vitro study

STATEMENT OF PROBLEM

Zirconia abutments have become popular as they provide favorable esthetic outcomes. However, studies investigating how abutment material affects abutment screw torque performance and implant conical surface morphological changes in internal conical connection systems are scarce.

PURPOSE

The purpose of this in vitro study was to investigate the influence of abutment material on abutment removal torque and implant conical surface morphological changes in internal conical connection implant-abutment assemblies of 2 diameters after simulated long-term oral use.

MATERIAL AND METHODS

Thirty abutments of 3 materials (1-piece titanium, 1-piece zirconia, zirconia with alloy base) and 2 diameters (regular, narrow) made by the original manufacturer were connected to internal conical connection implants and subjected to a standardized artificial aging process consisting of thermal cycling and mechanical cyclic loading with parameters corresponding to anterior and posterior mastication scenarios simulating long-term oral use. An abutment removal torque test was done before and after aging. Morphological changes in the implant conical contact surface were observed with a scanning electron microscope (SEM). Initial and after-aging torque loss values were calculated and analyzed separately with 1-way ANOVA and Tukey HSD post hoc tests (α=.05).

RESULTS

All specimens survived artificial aging. For initial and after-aging torque loss, the 1-piece zirconia groups showed significantly greater values (P<.001) for both diameters. In the SEM observation, the 1-piece zirconia groups showed distinct widespread surface damage while the other groups exhibited only minor damages.

CONCLUSIONS

Regardless of diameter, 1-piece zirconia abutments tend to induce more abutment removal torque loss and implant conical surface morphological changes than those with metal connections, both initially and after simulated long-term oral use. Zirconia abutments with an alloy base performed similarly to 1-piece titanium abutments.

Clinical Outcomes of Dental Implants with Two Different Internal Connection Configurations—A RCT

Background: The aim of the present study was to highlight clinical and radiographical differences among implants sharing the same macro-geometry but with two different prosthodontic connections. Methods: Patients requiring at least 2 implants in the posterior area of the jaw were randomly divided into two groups (Conical (CS) and Internal Hexagonal (IH) connection). At implant surgery (T0), insertion torque, implant stability quotient (ISQ values recorded by resonance frequency analysis, RFA), and soft tissue thickness (STH) were assessed. A 1-abutment/1-time protocol was applied, and the prosthesis was realized following a fully digital workflow. At the 36-month follow-up periapical x-rays were taken. In order to statistically analyse differences among the two groups and the different variables, paired T-test was used. Linear regression analysis was conducted to analyze how marginal bone loss (MBL) was affected by other independent variables. A neural network created to predict the success (good or not good) of the implant itself was implemented. Results: 30 out of 33 patients (14 males, 16 females, mean age: 68.94 ± 13.01 years) (32 CS and 32 IH) were analyzed. No implants failed. Marginal bone loss at the 3-year time-point was 0.33 ± 0.34 mm and 0.43 ± 0.37 mm respectively for CS and IH with a significant difference between the two groups (p = 0.004). The presence of keratinized gingiva (p = 0.034) significantly influenced MBL. Conclusions: Both the implant connections investigated presented optimal clinical outcomes with minimal marginal bone loss; however, CS implants and implants with the presence of a greater width of keratinized tissue presented significantly lower MBL.

The Effect of UV Treatment on Surface Contact Angle, Fibroblast Cytotoxicity, and Proliferation with Two Types of Zirconia-Based Ceramics

UV photofunctionalization of Zirconia-based materials for abutment fabrication is a promising approach that might influence the formation of a sound peri-implant seal, thus promoting long-term soft and hard tissue implant integration. This study aimed to evaluate the effect of UV treatment of test specimens made by two different ZnO₂-based ceramic materials on the hydrophilicity, cell cytotoxicity, and proliferation of human gingival fibroblasts (HGFs). Two Zirconia-based materials, high-translucent and ultra-translucent multi-layered Zirconia (Katana, Kuraray Noritake, Japan), were used to prepare a total of 40 specimens distributed in two equally sized groups based on the material (n = 20). The same surface finishing protocol was applied for all specimens, as suggested by the manufacturer. Half the specimens from each group were treated with UV-C light for 48 h. Water contact angle (WCA), fibroblast cytotoxicity, and proliferation were investigated. The WCA values for the high-translucent Zirconia ranged from 69.9° ± 6.4° to 73.7° ± 13.9° for the treated/non-treated specimens and from 79.5° ± 12.8° to 83.4° ± 11.4° for the ultra-translucent multi-layered Zirconia, respectively. However, the difference was insignificant (F(16) = 3.50, p = 0.292). No significant difference was observed for the fibroblast cytotoxicity test. The results for proliferation revealed a significant difference, which was material-dependent (F(8) = 9.58, p = 0.005). We found that UV surface photofunctionalization of ZrO₂-based materials alters the human gingival fibroblast cell viability, which might produce favourable results for cell proliferation.

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.

Marginal Adaptation and Microbial Leakage at Conometric Prosthetic Connections for Implant-Supported Single Crowns: An In Vitro Investigation

Encouraging clinical results were reported on a novel cone-in-cone coupling for the fixation of dental implant-supported crowns (Acuris, Dentsply Sirona Implants, Mölndal, Sweden). However, the presence or absence of a microgap and a potential bacterial leakage at the conometric joint has not yet been investigated. A misfit and a resulting gap between the conometric components could potentially serve as a bacterial reservoir that promotes plaque formation, which in turn may lead to inflammation of the peri-implant tissues. Thus, a two-fold study set-up was designed in order to evaluate the bidirectional translocation of bacteria along conometrically seated single crowns. On conometric abutments filled with a culture suspension of anaerobic bacteria, the corresponding titanium nitride-coated (TiN) caps were fixed by friction. Each system was sterilized and immersed in culture medium to provide an optimal environment for microbial growth. Positive and negative controls were prepared. Specimens were stored in an anaerobic workstation, and total and viable bacterial counts were determined. Every 48 h, samples were taken from the reaction tubes to inoculate blood agar plates and to isolate bacterial DNA for quantification using qrt-PCR. In addition, one Acuris test system was subjected to scanning electron microscopy (SEM) to evaluate the precision of fit of the conometric coupling and marginal crown opening. Throughout the observational period of one week, blood agar plates of the specimens showed no viable bacterial growth. qrt-PCR, likewise, yielded a result approaching zero with an amount of about 0.53 × 10⁻⁴ µg/mL DNA. While the luting gap/marginal opening between the TiN-cap and the ceramic crown was within the clinically acceptable range, the SEM analysis failed to identify a measurable microgap at the cone-in-cone junction. Within the limits of the in-vitro study it can be concluded that the Acuris conometric interface does not allow for bacterial translocation under non-dynamic loading conditions.

Effect of Implant Platform Connection and Abutment Material on Removal Torque and Implant Hexagon Plastic Deformation

Objectives  The aim of this study was to evaluate the plastic deformation of the hexagonal connection, and the removal torque of the implant-abutment joint of two dental implants combined with internal or external hexagonal connection implants after mechanical cycling.

Materials and Methods  Twenty-four dental implants were used in the study. Half of the implants had internal hexagonal connections (IH; Titamax II Plus) and the other half had external hexagonal connections (EH; Titamax Ti Ex). Four groups of two types of dental implant abutments (titanium: Ti, UCLA II Plus and zirconia: Zr, fabricated by CAD/CAM; n = 6) were investigated. The abutments received a metallic crown and the settings were submitted to mechanical cycling (MC; 10 ⁶ cycles, axial load, 120N). The connection surface area was measured by scanning electron microscope (SEM) images. The removal torque was evaluated and the plastic deformation of the hexagonal surface of the implant was measured by comparing the images before and after MC.

Statistical Analysis  Paired- t test was used to analyze the data statistically at a significance level of α = 0.05.

Results  The torque values decreased for all groups after MC, and the hexagonal surface area decreased due to plastic deformation for IH and EH associated with Zr abutments.

Conclusions  Zirconia abutments showed the worst plastic deformation of the implant connection surface and torque loosening when associated with IH implant.

What is the Optimal Material for Implant Prosthesis?

Implant dentistry has shifted to prosthetically guided implant planning and placement. This shift has influenced the range of available dental materials to restore single crowns and partially and fully edentulous jaws with dental implants. This article presents an overview of the available options to restore dental implants. The qualities that define an ideal restoring material are discussed along with the most commonly used materials with their advantages and limitations. Because clinicians face different clinical scenarios in their practice, the discussion sums up the best techniques and materials that are useful in addressing these nonideal situations.

Biological aspects: Summary and consensus statements of group 2. The 5th EAO Consensus Conference 2018

OBJECTIVES

This publication reports the EAO Workshop group-2 discussions and consensus statements which provided the scientific evidence on the influence of biological parameters on implant-related clinical outcomes.

MATERIAL AND METHODS

The first publication was a systematic review on the biological effects of abutment material on the stability of peri-implant marginal bone levels and the second, a critical narrative review on how peri-implant diagnostic parameters correspond with long-term implant survival and success. The group evaluated the content of both publications, made corrections and recommendations to the authors and agreed on the consensus statements, clinical recommendations and recommendations for future research, which are described in this consensus report.

RESULTS

Tested abutment materials can be considered appropriate for clinical use according to the observation period studied (mean 3.5 years). Mean peri-implant bone loss and mean probing pocket depths are not adequate outcomes to study the prevalence of peri-implantitis, while the reporting of frequency distributions is considered more appropriate.

CONCLUSIONS

Titanium is currently considered the standard of care as abutment material, although other materials may be more suitable for aesthetic locations. Peri-implantitis should be diagnosed through composite evaluations of peri-implant tissue inflammation and assessment of marginal bone loss with different thresholds.

Influence of scaling procedures on the integrity of titanium nitride coated CAD/CAM abutments

PURPOSE

To determine the extent of treatment traces, the roughness depth, and the quantity of titanium nitride (TiN) removed from the surface of CAD/CAM abutments after treatment with various instruments.

MATERIALS AND METHODS

Twelve TiN coated CAD/CAM abutments were investigated for an in vitro study. In the test group (9), each abutment surface was subjected twice (150 g vs. 200 g pressure) to standardized treatment in a simulated prophylaxis measure with the following instruments: acrylic scaler, titanium curette, and ultrasonic scaler with steel tip. Three abutments were used as control group. Average surface roughness (Sa) and developed interfacial area ratio (Sdr) of treated and untreated surfaces were measured with a profilometer. The extent of treatment traces were analyzed by scanning electron microscopy.

RESULTS

Manipulation with ultrasonic scalers resulted in a significant increase of average surface roughness (Sa, P<.05) and developed interfacial area ratio (Sdr, P<.018). Variable contact pressure did not yield any statistically significant difference on Sa-values for all instruments (P=.8). Ultrasonic treatment resulted in pronounced surface traces and partially detachment of the TiN coating. While titanium curettes caused predominantly moderate treatment traces, no traces or detectable substance removal has been determined after manipulation with acrylic curettes.

CONCLUSION

Inappropriate instruments during regular plaque control may have an adverse effect on the integrity of the TiN coating of CAD/CAM abutments. To prevent defects and an increased surface roughness at the transmucosal zone of TiN abutments, only acrylic scaling instruments can be recommended for regular maintenance care.