Cement Residues Research Articles

Performance evaluation of carbon quantum dots impregnated glass ionomer cement to avoid peri-implant disease

Dental cement residues exacerbate peri-implant tissue irritation and peri-implantitis. The present study aims to evaluate the cytotoxicity, physiochemical, optical, and rheological properties of carbon quantum dots (CQDs) impregnated glass ionomer cement (GIC). Surface passivated fluorescent CQDs were synthesized using citric acid via thermal decomposition and blended with GIC. Characterization studies and rheological measurements were made to evaluate their performance. 3D-printed dental implant models cemented with GIC and GIC-CQD were compared to analyze excess cement residues. MTT assay was performed with human dental pulp stem cells (hDPSCs) and statistically analyzed using ANOVA and Tukey’s test. CQDs with a particle dimension of ∼2 nm were synthesized. The amorphous property of GIC-CQD was confirmed through XRD. The fluorescence properties of GIC-CQD showed three times higher emission intensity than conventional GIC. GIC-CQD attained maturation with a setting time extended by 64 s than GIC. Cement residue of size 2 mm was detected with a UV light excitation at a distance between 5 to 10 cm. Biocompatibility at 0.125 mg ml−1 dilution concentrations of GIC-CQD showed viability greater than 80% to hDPSCs. For the first time, we report that CQDs-impregnated GIC is a unique and cost-effective strategy for in-situ detection of excess cement rapidly using a hand-held device. A novel in-situ rapid detection method enables the dentist to identify residual cement of size less than 2 mm during the implantation. Therefore, GIC-CQD would replace conventional GIC and help in the prevention of peri-implant diseases.

Prediction of excess cement residues using a regression model to avoid peri-implant diseases: An in vitro study.

Dental implant restorations attached to cement can potentially result in peri-implant mucositis and peri-implantitis if cement residues are present. Effectively predicting and eliminating such dental cement residues is crucial for preventing complications. This study focuses on creating a regression model using the pixel values to predict the Excess Cement Residues (ECR) by employing an octagonal surface imaging approach. A model featuring gingival imitation, ten abutments, and ten crowns was created, and the cemented implants underwent thorough photographic and analytical assessment. The ECR was determined through two distinct approaches: the Computerized Planimetric Method (CPM) and the weighing method. Across ten implants in this in vitro study, ECR varied from 0.3 to 21 mg, with an average of 5.69 mg. The findings reveal a higher amount of ECR on the distal, mesiobuccal, and mesial sides. Utilizing Pearson's correlation, a coefficient value of r = 0.786 signifies a strong correlation between CPM and the weighing method. The regression model further aids in predicting ECR based on pixel values. The octagonal surface imaging approach not only vividly captures information about ECR in the implant cementation region but also emphasizes the feasibility of ImageJ as an effective tool for detecting ECR. The congruence between CPM and the weighing method results supports the application of the regression model for precise ECR prediction.

Tips and tricks of cement removal in the case of revision surgery

In Germany, current revision rates after arthroplasty range between 28-37%. In particular, remaining cement residues are causative for additional revision surgery after periprosthetic joint infection, which is why complete cement removal is of high importance. However, the removal of remaining cement residues often confronts the surgeon with technical challenges. Complication-free and complete cement removal requires extensive preoperative preparation in order to develop the best possible surgical strategy. Special instrument sets to facilitate cement removal in revision cases are available from various manufacturers. In addition to endoluminal approaches, access enhancements such as extended osteotomies exist to facilitate complete cement removal. Finally, the surgeon should be able to give the indication for an intraoperative procedural change after adefined time interval.

Ready-To-Use and Rapidly Biodegradable Magnesium Phosphate Bone Cement: In Vivo Evaluation in Sheep.

In clinical practice, hydroxyapatite (HA) cements for bone defect treatment are frequently prepared by mixing a powder component and a liquid component shortly before implantation in the operation theater, which is time-consuming and error-prone. In addition, HA cements are only slightly resorbed, that is, cement residues can still be found in the bone years after implantation. Here, these challenges are addressed by a prefabricated magnesium phosphate cement paste based on glycerol, which is ready-to-use and can be directly applied during surgery. By using a trimodal particle size distribution (PSD), the paste is readily injectable and exhibits a compressive strength of 9-14MPa after setting. Struvite (MgNH4 PO4 ·6H2 O), dittmarite (MgNH4 PO4 ·H2 O), farringtonite (Mg3 (PO4 )2 ), and newberyite (MgHPO4 ·3H2 O) are the mineral phases present in the set cement. The paste developed here features a promising degradation of 37% after fourmonths in an ovine implantation model, with 25% of the implant area being newly formed bone. It is concluded that the novel prefabricated paste improves application during surgery, has a suitable degradation rate, and supports bone regeneration.

Effect of Temporary Cement, Surface Pretreatment and Tooth Area on the Bond Strength of Adhesively Cemented Ceramic Overlays—An In Vitro Study

Several viewpoints have been reported regarding the effect of temporary cements, different surface pretreatment protocols before adhesive cementation, and predictive factors. This in vitro study tested if temporary cement, pretreatment of the tooth surface, the size of enamel or dentine influence adhesive cementation to zirconia ceramics. Twenty premolars were prepared for determination of enamel and dentin area, bond strength test and failure analysis. The samples were divided into two groups: untreated prior adhesive cementation (n = 10) and with temporary cementation done, pretreated prior adhesive cementation (n = 10). Zirconia overlays (Katana Zirconia STML) were cemented on the grounded flat teeth surfaces using Panavia V5. An additional six premolars underwent dentine tubule analysis with SEM to detect temporary cement residues after temporary cementation on an untreated tooth surface (n = 3) and on a pretreated surface (n = 3). The independent sample t-test was used to compare the two groups and the means of the total tooth, dentin or enamel areas did not differ significantly between the untreated and pretreated specimens. The mean tensile bond strength was significantly (p = 0.005) higher in the pretreated specimens (337N) than in the untreated ones (204N). The overall multivariable linear regression model with three predictors (surface pre-treatment, enamel area and dentine area) was significant (p = 0.003), among which the size of enamel was the strongest predictor (β = 0.506; p = 0.049), followed by the pretreatment effect (β = 0.478; p = 0.001) and the size of dentin area (β = -0.105; p = 0.022).

The Prevalence, Diagnosis, Management and Prognosis of PeriImplantitis

Peri-implantitis, characterized by inflammatory reactions resulting in bone loss around dental implants integrated with the jawbone, presents a significant challenge in implant dentistry. While bacterial biofilms are recognized as the primary culprits in peri-mucositis, peri-implantitis is often attributed to mechanical stresses stemming from biomechanical deficiencies, along with a myriad of other contributing factors, including implant positioning, oral hygiene, cement residues, host responses, implant surface quality, bone density, untreated periodontal issues, smoking, alcohol consumption, endodontic problems, and diabetes. Despite extensive research efforts, a universally accepted protocol for effectively managing peri-implant diseases remains elusive. This review provides an overview of peri-implantitis, offering valuable insights into its multifactorial etiology, diagnostic challenges, and evolving therapeutic strategies. By consolidating existing knowledge, this review aims to equip clinicians with a more informed approach to managing this complex and prevalent condition, ultimately improving patient care in implant dentistry.

The effect of mechanical and chemo-mechanical temporary cement cleaning methods on shear bond strength with self-adhesive resin cement (an in-vitro study)

BackgroundAdhesive tooth-colored restorations are strongly dependent on the substrate surface cleanliness to allow intimate contact between resin cement and dentin surface, so several methods were adopted for the total cleaning of temporary cement residues. This study aimed to assess the effect of mechanical and chemo-mechanical cleaning methods of temporary cement on the immediate shear bond strength of self-adhesive resin cement to dentin surface.MethodsForty freshly extracted lower first premolars were cut to expose a flat dentin surface. Discs of temporary crown composite resin material were constructed and cemented to the flat dentin surface using resin-based and non-eugenol temporary cement then stored at room temperature in distilled water. Dividing of samples into two groups according to the method of temporary cement cleaning. Group I (n = 20) mechanical cleaning using the rotary instrument, and group II (n = 20) chemo-mechanical cleaning using chlorhexidine-containing scrub. CAD/CAM reinforced Composite discs were bonded to the dentin surface using self-adhesive composite resin cement, then measurement of shear bond strength was done using a universal testing machine. Further analysis of failure mode after debonding was performed by Scanning electron microscope.ResultsNo statistically significant difference was found between the mean shear bond strength of the two cleaning methods (P-value = 0.636). Regardless of the cleaning method, the group cemented with resin-based temporary cement showed statistically significantly higher mean shear bond strength than non-eugenol temporary cement (P-value = 0.048).ConclusionBoth cleaning methods (mechanical and chemo-mechanical) applied in this study were effective in cleaning temporary cement remnants from the dentin substrate surface with statistically significant differences between results of shear bond strength with significantly higher values recorded with resin-based temporary cement.

Ultrasonic bone cement removal efficiency in total joint arthroplasty revision: A computer tomographic-based cadaver study.

Polymethylmethacrylate (PMMA) removal during septic total joint arthroplasty revision is associated with a high fracture and perforation risk. Ultrasonic cement removal is considered a bone-preserving technique. Currently, there is still a lack of sound data on efficacy as it is difficult to detect smaller residues with reasonable technical effort. However, incomplete removal is associated with the risk of biofilm coverage of the residue. Therefore, the study aimed to investigate the efficiency of ultrasonic-based PMMA removal in a human cadaver model.The femoral components of a total hip and a total knee prosthesis were implanted in two cadaver femoral canals by 3rd generation cement fixation technique. Implants were then removed. Cement mantle extraction was performed with the OSCAR-3-System ultrasonic system (Orthofix®). Quantitative analysis of cement residues was carried out with dual-energy and microcomputer tomography.With a 20 µm resolution, in vitro microcomputer tomography visualized tiniest PMMA residues. For clinical use, dual-energy computer tomography tissue decomposition with 0.75 mm resolution is suitable. With ultrasound, more than 99% of PMMA was removed. Seven hundred thirty-fourresidues with a mean volume of 0.40 ± 4.95 mm3 were identified with only 4 exceeding 1 cm in length in at least one axis.Ultrasonic cement removal of PMMA was almost complete and can therefore be considered a highly effective technique. For the first time, PMMA residues in the sub-millimetre range were detected by computer tomography. Clinical implications of the small remaining PMMA fraction on the eradication rate of periprosthetic joint infection warrants further investigations.

The Conometric Connection for the Implant-Supported Fixed Prosthesis: A Narrative Review

Aim: The conometric concept was proposed as a possible connection between the abutment and the prosthetic coping. This research aimed to review the features and possible clinical uses of this connection in an implant-supported fixed prosthesis. Methods: An electronic search was conducted on an online database for the topic in object; articles published in international literature were considered and the research gave 17 results, and 6 parameters were analyzed. Results: This connection eliminated the possibility of cement residues in the subgingival region, reducing the risk of inflammation of peri-implant soft and hard tissues; not having to remove the cement residues, it is possible to place the margins in more apical portions, improving the aesthetics outcomes of the rehabilitations. It is also known that the retention by means of a screw causes a weakening of the restoration. The retentive force is adequate for fixed rehabilitation even after a high number of insertion–disengagement cycles; in vitro studies have also shown a high bacterial sealing. Implant rehabilitation using preformed components, such as conometric hoods, is helpful for CAD/CAM, so a digital workflow is possible. Several types of prosthesis were presented, all of which demonstrated adequate clinical performance in the follow-up observation. Conclusions: This type of connection seems to be suitable to support fixed implant rehabilitations, but long-term clinical studies are needed to validate this system.

Strategies for stem revision : Surgery planning, implant removal and reimplantation

Femoral revision represents achallenging procedure in its surgical planning and technical execution. The results are mainly dependent on the bone loss present, the quality of the implant removal and the choice of revision system. Patient-specific factors such as age, comorbidities, bone quality or even the localization of the cement have adecisive influence on the surgical strategy. Appropriate preoperative preparation, including the presence of the necessary special instruments, which are essential for gentle implant removal, is indispensable to achieve the best possible result. Abone-sparing implant removal can be particularly challenging, especially in the case of well-fixed stems and cement residues, which may extend far beyond the isthmus. In such situations, atransfemoral approach should be considered. Cementless reimplantation using modular or non-modular titanium stems is currently the preferred treatment of choice for most revisions. In elderly, low-demand patients or with poor bone quality, cemented revision remains agood alternative treatment option.

Farklı mukozal kalınlıkların implant çevresi krestal kemik kaybına etkisi

A dental implant is a treatment option that is widely used nowadays and provides to giving the aesthetic, function, and phonation back to the patient in dental deficiencies. Nevertheless, the inefficacies of dental implants also draw attention for various reasons. Factors causing early period implant inefficacies are being analyzed and reasons that may be affecting marginal bone loss are being elaborated. In the literature, factors causing marginal bone loss such as premature prosthetic loading, neglected cement residues at the prosthesis stage, micro-gap foundation, infection foundation on the surgery region and traumatic surgery draws attention. One of these reasons is the thickness of the mucosa covering the region that the implant is placed (phenotype). The purpose of our review is to discuss the effect of mucosal thickness in the surgical area on the marginal bone loss in the implant area, within the scope of the literature.

Utilization of concrete slurry waste for soil stabilization

The stabilization of clay soils is one of the crucial problems of engineering, because it determines the long-term stability and operability of structures, especially in case of infrastructure. Present work is focused on the experimental investigation of the utilization of concrete slurry waste (CSW), which is generated during ready-mix concrete production, as a stabilizing agent of clay soil. The alkaline character and content of cement residues in the studied waste material provide suitable potential for the proposed application. The contribution of CSW to soil stabilization was investigated in terms of compressive strength, the California bearing ratio (CBR) and Immediate bearing index (IBI). The nature of the stabilization process was documented by scanning electron microscopy (SEM) and monitored by thermal analysis and X-ray powder diffraction (XRD). The performed experimental program was organized as benchmark test to express the stabilizing properties of CSW in comparison to ordinary Portland cement (OPC). The studied CSW contributes to soil stabilization by the calcium ion exchange, what was documented by IBI, and by the formation of hydraulic products. The studied CSW attained a stabilizing effect by 38% than with the same dose of OPC in terms of compressive strength. The studied waste material has great potential to achieve economic and environmental savings, if applied to soil stabilization.

A Systematic Review of Cementation Techniques to Minimize Cement Excess in Cement-Retained Implant Restorations.

Background: The most used types of retention of implant-supported prostheses are screw-retained or cement-retained restorations. The advantages and disadvantages of both have been identified by various authors over the years. However, cement-retained implant crowns and fixed partial dentures are among the most used types of restorations in implant prostheses, due to their aesthetic and clinical advantages. When cemented prostheses are made on implants, the problem of cement residues is important and often associated with biological implant pathologies. The objective of this research was to establish to what extent the techniques to reduce excess cement really affect the volume of cement residues. Materials and Methods: This review was written following the PRISMA statement; a detailed search was carried out in three different electronic databases—PubMed, Scopus, and Cochrane Library. The inclusion criteria were prospective clinical studies, with at least 10 participants per group, and with at least 6 months of the follow-up period. Results: There have been many proposals for techniques supposed to reduce the amount of excess cement in the peri-implant sulcus and on the prosthetic components, but of these, which are exceptional in their in vitro capabilities, very few have been clinically validated, and this represents the real limitation and a great lack of knowledge regarding this topic. Three articles met the inclusion criteria, which were analyzed and compared, to obtain the information necessary for the purposes of the systematic review. Discussion: Extraoral cementation can reduce the excess cement, which, after a normal excess removal procedure, is, nevertheless, of such size that it does not affect the possibility of peri-implant pathologies developing. All these studies concluded that a small amount of cement residue is found in the gingival sulcus, and using eugenol-free oxide cements, the residues were only deposited on the metal surfaces, with a better peri-implant tissues health. Conclusion: Despite the limitations of this study, it was possible to carefully analyze these characteristics and obtain valuable suggestions for daily clinical practice. Resinous cements are considered, due to the free monomers present in them, toxic for the soft tissues. The provisional zinc-oxide cements, also eugenol-free, represent the ideal choice. The different grades of retentive forces provided by these cements do not seem to have clinical effects on the decementation of restorations.

Cemented versus screw-retained posterior implant-supported single crowns: A 24-month randomized controlled clinical trial.

To compare the incidence of biological and technical complications of cemented and screw-retained monolithic lithium-disilicate implant-supported posterior single crowns. Forty-one subjects with a total of 56 implants received randomly allocated 28 cemented and 28 screw-retained crowns. In the screw-retained group, monolithic lithium-disilicate restorations were luted to titanium bases extraorally. In the cemented group, monolithic lithium-disilicate crowns were cemented on individualized titanium abutments intraorally. All restorations were examined according to modified FDI criteria within 2weeks of inserting the crowns (baseline) and after 12 (n=46) and 24 (n=43) months. Bone loss was evaluated by standardized radiographs at baseline and 12months. After 12months, the incidence of mucositis (positive bleeding on probing) was 14.2% (screw-retained) and 17.9% (cement-retained). The gingival and plaque index and a mean marginal bone loss between 0.03-0.15mm showed no significant difference between the groups. In the cemented group, cement residues were detected at baseline at two restorations (6.9%) by radiographic examination. A complete digital workflow was realized in most cases (85.7%). At 24months, no restoration had failed, and no chipping of the ceramic had occurred. In the screw-retained group, screw loosening occurred in one implant. In both groups, there was obvious deterioration in the quality of 32% of the occlusal and of 18% of the proximal contact points. The type of retention mode of monolithic implant-retained lithium-disilicate posterior crowns had no influence on the biological and technical complication rate.

Temporary cement residues affect the bond strength and dentin penetration of self-adhesive resin cement in fiberglass post cementation.

This study evaluated the persistence of eugenol-containing (PR, Provy) or eugenol-free (RT, Relyx Temp, and TB, Temp Bond) temporary cement residues and its effects on push-out bond strength and dentinal penetration of the self-adhesive resin cement (Relyx U200). Eighty human roots were endodontically treated and post space prepared. Fourty specimens were distributed in four groups (n=10): Control (CO), without any clinical procedure, PR, RT, and TB, where a metallic post was cemented with one of the temporary cements. After metallic post removal, hemi sections post space were submitted to SEM analysis. Another specimens were distributed in similar groups, but fiberglass post was cemented using Relyx U200 cement and submitted to push-out bond strength and dentinal penetration cement analysis, in post space thirds. SEM analysis were evaluated by Kruskal-Wallis and Dunn tests, while bond strength and dentinal penetration were evaluated by ANOVA One-Way and Tukey test (p < .05). Only in apical thirds, PR, RT, and TB showed higher persistence of residues than CO. In bond strength, PR, RT, and TB showed lower values than CO, in all post space thirds (p < .05). But to dentinal penetration, PR, RT, and TB presented lower values than CO only in apical thirds (p < .05). There is the greatest persistence of temporary cement residues only in apical post space third, providing less dentinal penetration of the self-adhesive resinous cement. However, the previous use of temporary cements has negative effects on the bond strength cementation system, regardless of the third evaluated.

İKİ FARKLI REZİN SİMANIN DENTİN YÜZEYİNE BAĞLANMA DAYANIKLIĞINA GEÇİCİ SİMAN UZAKLAŞTIRMA YÖNTEMLERİNİN ETKİSİ

Amaç: Bu in vitro çalışma iki farklı rezin simanın dentin yüzeyine bağlanma dayanıklılığına geçici siman (Cavex) uzaklaştırma yöntemlerinin etkisinin incelenmesi amacıyla yapıldı. Gereç ve Yöntem: Çalışmada 40 adet yeni çekilmiş insan molar dişlerinin oklüzal yüzeyleri dentin yüzeyi açığa çıkıncıya kadar prepare edildi. Deney grubunu oluşturan dişlerin her biri 15 mm çap ve 10 mm yüksekliğindeki polimerik tüplere oklüzal yüzeyleri paralelometrenin dikey eksenine dik olacak şekilde yerleştirildi ve dişler otopolimerizan şeffaf akrilik silindir bloklar içerisine gömüldü. Bir grup (N=5) örnek kontrol grubu olarak ayrıldıktan sonra diğer örnek yüzeylerine çapları 3 mm olan kalıplar içerisinde üretici firmanın talimatlarına uygun olarak öjenolsüz geçici siman yerleştirildi. 37°C’de distile suda 7 gün süreyle bekletilen örneklerin yüzeyindeki siman artıkları 10 sn süreyle keskin bir el aleti, air-flow ve fosforik asit olmak üzere üç farklı teknikle uzaklaştırıldı. Daha sonra tüm dentin yüzeylerine 5 N luk yük altında, Panavia F2.0 ve Panavia SA rezin siman 3 mm lik kalıplar ile yapıştırıldı. Kesme tipi (shear bond strength) bağlanma dayanıklılıkları Universal test makinası kullanılarak dakikada 1.0 mm başlık hızı ile ölçüldü. Bağlanma değerleri ve standart sapmaları hesaplandı. Elde edilen sonuçlar varyans analizi ve Tukey çoklu karşılaştırma ve t testi ile değerlendirildi. Bulgular: Temizleme yöntemleri (p<0.05) ve siman türünün anlamlı (p<0.001) olduğu, interaksiyonların ise anlamlı olmadığı (p>0.05) istatistiksel olarak saptandı. Tartışma: Adeziv simanlarla simantasyon yapılmadan önce, geçici simanların tam olarak temizlenmesi gerekir. Anahtar Kelimeler: Geçici siman, rezin siman, dentine bağlanma, temizleme yöntemleri The Effect of Temporary Cementation Removal Methods on Bonding Strength of Two Different Resin Cements on the Dentine Surface ABSTRACT Aim: The aim of this in vitro study was carried out to investigate the effect of temporary cements (Cavex) removal methods on the bond strength of two different resin cements to the dentin surface. Material and Methods: In the study, 40 fresh extracted human molar teeth were prepared until exposed the dentin surface. Each of the teeth forming the experimental group was placed into polymeric tubes of 15 mm diameter and 10 mm height and their occlusal surfaces were placed perpendicular to the vertical axis of the parallelometer and the teeth were embedded in autopolymerizing transparent acrylic cylinder blocks. After separating a group (N=5) as the sample control group, the non-eugenic temporary cement was placed in the molds with diameters 3 mm on the other sample surfaces in accordance with the manufacturer's instructions. The cement residues on the surface of the samples which were kept in distilled water at 37 ° C for 7 days were removed with three different techniques as a sharp hand tool, air-flow and phosphoric acid for 10 sec. Then, under 5 N load on all dentin surfaces, Panavia F2.0 and Panavia SA resin cements were bonded with 3 mm molds. Resistance to shear bond strength bonding was measured using a universal test machine with a head speed of 1.0 mm per minute. Attachment values and standard deviations were calculated. The results were evaluated by variance analysis and Tukey multiple comparison and t test. Results: The removal methods (p<0.05) and cement type (p<0.001) were significant effect on bonding strength of dentin surface. However, the interaction of between removal methods and cement type not significant effect on bonding strength (p>0.05). Conclusion: Before the adhesive cementation, the temporary cements must be thoroughly cleaned. Keywords: Temporary cement, resin cement, dentin binding, cleaning methods

A distinctive release profile of vancomycin and tobramycin from a new and injectable polymeric dicalcium phosphate dehydrate cement (P-DCPD)

A novel injectable polymeric dicalcium phosphate dehydrate (P-DCPD) cement was developed with superior mechanical strength and excellent cohesion. The purpose of this study was to assess the in vitro performance of P-DCPD loaded with vancomycin (VAN-P), tobramycin (TOB-P) and combination of both (VAN/TOB-P) (10%, w/w). There is a distinctive release profile between VAN and TOB. VAN-P showed decreased initial burst (<30% within 3 d) and sustained VAN release (76% in 28 d). In the presence of TOB (VAN/TOB-P), >90% of VAN was released within 3 d (p < 0.05). Slow and limited TOB release was observed both in TOB-P (<5%) and in TOB/VAN-P (<1%) over 28 d. Zone of inhibition (ZOI) of Staphylococcus aureus growth showed that eluents collected from VAN-P had stronger and longer ZOI (28 d) than that from TOB-P (14 d, p < 0.05). Direct contact of VAN-P, TOB-P and VAN/TOB-P cements displayed persistent and strong ZOI for >3 weeks. Interestingly, the cement residues (28 d after drug release) still maintained strong ZOI ability. P-DCPD with or without antibiotics loading were nontoxic and had no inferior impacts on the growth of osteoblastic MC3T3 cells. VAN-P and TOB-P were injectable. No significant influence on setting time was observed in both VAN-P (11.7 ± 1.9 min) and VAN/TOB-P (10.8 ± 1.5 min) as compared to control (12.2 ± 2.6 min). We propose that a distinctive release profile of VAN and TOB observed is mainly due to different distribution pattern of VAN and TOB within P-DCPD matrix. A limited release of TOB might be due to the incorporation of TOB inside the crystalline lattice of P-DCPD crystals. Our data supported that the bactericidal efficacy of antibiotics-loaded P-DCPD is not only depend on the amount and velocity of antibiotics released, but also probably more on the direct contact of attached bacteria on the degrading cement surface.

In vitro cytotoxicity of different dental resin-cements on human cell lines

Adhesive resin-cements are increasingly used in modern dentistry. Nevertheless, released substances from resin materials have been shown to cause cellular toxic effects. Disc-shaped specimens from 12 different resin cements and one conventional zinc phosphate cement were prepared and used for direct stimulation of five different human cell lines via transwell cell culture system or in an indirect way using conditioned cell culture media. Cytotoxicity was determined using LDH and BCA assays. All tested cements led to a decrease of cell viability but to a distinct extent depending on cell type, luting material, and cytotoxicity assay. In general, cements exhibited a more pronounced cytotoxicity in direct stimulation experiments compared to stimulations using conditioned media. Interestingly, the conventional zinc phosphate cement showed the lowest impact on cell viability. On cellular level, highest cytotoxic effects were detected in osteoblastic cell lines. All resin cements reduced cell viability of human cells with significant differences depending on cell type and cement material. Especially, osteoblastic cells demonstrated a tremendous increase of cytotoxicity after cement exposure. Although the results of this in vitro study cannot be transferred directly to a clinical setting, it shows that eluted substances from resin cements may disturb osteoblastic homeostasis that in turn could lead to conditions favoring peri-implant bone destruction. Thus, the wide use of resin cements in every clinical situation should be scrutinized. A correct use with complete removal of all cement residues and a sufficient polymerization should be given the utmost attention in clinical usage.

Influence of re-cementation on the retention of CAD/CAM zirconia copings over short titanium and zirconia abutments

Objective: The aim of this study was to comparatively evaluate the effects of re-cementation on the retention of zirconia copings, which were cemented to short titanium and zirconia abutments with self-adhesive resin cement. Materials and Method: Twelve titanium (Nucleoss T4 implants, NucleOSS T4 flat abutment, İzmir, Turkey) and 12 zirconia abutments (Zirkonzahn, Zirkonzahn GmbH, Bruneck, Italy) were used in this in vitro study. The titanium abutments were shortened to 3 mm and embedded in acrylic by fixing them with analogues. The zirconia abutments and copings were produced by scanning the abutments using the computer-aided design and manufacturing (CAD/CAM) method. All zirconia copings were cemented to the titanium and zirconia abutments with self-adhesive resin cement. Samples were subjected to a pull-out test in a universal testing device, and the bond strength values were recorded. Cement residues on the abutments and copings were removed with a handpiece that had a round head carbon steel bur, and an explorer. The copings were then re-cemented and retested using the pull-out test, and the strength values were recorded. Descriptive statistics were applied to the data, and the mean and standard deviation values were calculated. Bonferroni corrections with pairwise comparisons were used to compare the group and test effect at each level. P&amp;lt;0.01 was considered as statistically significant. Results: The effect of the pre-test and end-test on bond strength (p&amp;lt;0.001), the group effect on titanium and zirconia (p&amp;lt;0.001) and the test-group interaction effect (p&amp;lt;0.001) were all found to be statistically significant. A significant difference was observed between the titanium and zirconia samples in terms of bond strength when the pre-test and end-tests were compared (titanium: p&amp;lt;0.05, zirconia: p&amp;lt;0.001). The end-test bond strength values were significantly lower than the pre-test bond strength values. Additionally, there was a significant difference between the titanium and zirconia samples in terms of bond strength change on comparison of the pre-test and the end-test. Decrease in bond strength values was higher in the zirconia samples (p&amp;lt;0.001). Conclusion: Re-cementation may adversely affect the bond strength of single-unit restorations on short abutments. In the case of re-cementation, a higher retention loss may occur in zirconia abutments than in titanium abutments.

DYNAMICS OF THE LEVEL OF PRO- AND ANTI-INFLAMMATORY CYTOKINES IN THE CREVICULAR FLUID AFTER DIRECT AND INDIRECT RESTORATION

The restoration of discolored teeth is conducted by direct and indirect restoration techniques. Impairment of marginal periodontium is possible during the stages of both direct and indirect restoration in gum retraction, cofferdam application, grinding and polishing for direct restoration, removal of fixation cement residues near indirect restorations and finishing preparation of the connection boundary with the tooth. Furthermore, the restorations affect the periodontal tissues in the long term due to the formation of biofilm and dental plaque in the precervical area of the abutment teeth.&#x0D; One of the earliest ways to detect the inflammatory process in the marginal periodontium is to determine the level of pro-inflammatory and anti-inflammatory cytokines in the crevicular fluid.&#x0D; The aim of the research was to study the level of pro-inflammatory and anti-inflammatory cytokines in the crevicular fluid after direct and indirect restorations, which were performed by classical fixation and via the proposed method of fixation on the heated composite in 24 hours and 12 months.&#x0D; Materials and methods of the research. For clinical substantiation and comparison of direct and indirect ceramic restorations with classical fixation and the proposed method of fixation on the heated composite, we examined and collected the material in 24 hours and 12 months after treatment in 84 patients, aged 18-65, with dental discoloration and defects of the crown of the frontal teeth.&#x0D; All patients were divided into 7 clinical groups with 12 patients in each. Group 1 was a control, which included patients with intact dentition, without discoloration and defects of the hard tissues of the teeth of the frontal area; group 2 embraced patients who were treated by direct restoration (a day after treatment); group 3 comprised patients, treated with indirect ceramic restorations, which were fixed by conventional methods on a double-cured composite (one day after treatment); group 4 included patients, whose veneers were fixed to the heated composite (one day after treatment); group 5 embraced patients 12 months after treatment with direct restorations; group 6 included patients, treated with indirect ceramic restorations, which were fixed by conventional methods on a double-cured composite (12 months after treatment); group 7 comprised patients, whose veneers were fixed to the heated composite (12 months after treatment). The material for the study was the crevicular fluid. We determined the tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and interleukin 10 (IL-10).&#x0D; The study showed that in all three study groups in 24 hours, the significant predominance of the IL-6 content as compared to the control group was observed. The presence of IL-6 in the crevicular fluid indicates inflammation in the periodontium. The level of another pro-inflammatory cytokine, TNF-α, was higher in the groups with direct and indirect restorations, which were fixed by conventional methods to the composite of double hardening, which relates to adverse factors, since this mediator activates the processes of osteoresorption and enhances inflammatory reactions in the periodontal tissues. When comparing the concentrations of pro-inflammatory cytokines TNF-α and IL-6 in the crevicular fluid between the direct and indirect restoration group, we detected their significantly lower level in the groups where indirect restorations were performed, fixed on the composite cement and on the heated composite. The concentration of IL-10 in the groups with direct and indirect restoration, fixed on the heated composite, was the same, and in the group with indirect restoration, fixed on the composite cement, it increased significantly. After 12 months, the level of pro-inflammatory cytokines TNF-α and IL-6 was significantly higher in the direct restoration group as compared to the indirect restoration groups and with fixation on the composite cement and on the heated composite. The absence of significant differences in pro-inflammatory cytokines in this period for the groups of indirect restorations indicates the absence of inflammatory phenomena in the marginal periodontium and proves the possibility of applying the method of veneer fixation on the heated composite.