Bone tissue 3D bioprinting in regenerative dentistry through the perspective of the diamond concept of healing: A narrative review.

Three-dimensional bioprinting technology appears to be a promising solution for the treatment and reconstruction of a wide range of maxillofacial bone defects. In this review, the authors discuss different bioprinting solutions and options in the context of the 4 factors of bone healing: structures or scaffolds, osteogenic cells, growth factors, and stabilization (diamond concept of healing), as well as the influence of a 5th factor - vascularization. Bone is a complex tissue; hence, bone bioprinting may require different technical approaches and mixed methods. Ultraviolet (UV) crosslinkable hydrogels, such as gelatin methacryloyl (GelMA), are among the most promising bioinks; they are enhanced by hydroxyapatite or 1-2.5 mm beta-tricalcium phosphate (ß-TCP) granules and porous scaffolds with recommended pore sizes greater than 300 µm. The advantages of mesenchymal stem cells (MSCs) are their significant availability, low tumorigenicity, and great potential for differentiation into osteoblasts or endothelial cells (ECs). Although growth factors require advanced delivery systems, they provide excellent improvement in the functionality of printed tissues. A proper vasculature system supplies cells with oxygen and nutrients, removes waste products, promotes osteogenesis, prevents ischemic necrosis, and improves the mechanical properties of bone. With all of these aspects perfectly balanced and working in synergy, the clinical use of bioprinting is only a matter of time.

An Experimental Anodized and Low-Pressure Oxygen Plasma-Treated Titanium Dental Implant Surface-Preliminary Report.

Chemical composition and physical parameters of the implant surface, such as roughness, regulate the cellular response leading to implant bone osseointegration. Possible implant surface modifications include anodization or the plasma electrolytic oxidation (PEO) treatment process that produces a thick and dense oxide coating superior to normal anodic oxidation. Experimental modifications with Plasma Electrolytic Oxidation (PEO) titanium and titanium alloy Ti6Al4V plates and PEO additionally treated with low-pressure oxygen plasma (PEO-S) were used in this study to evaluate their physical and chemical properties. Cytotoxicity of experimental titanium samples as well as cell adhesion to their surface were assessed using normal human dermal fibroblasts (NHDF) or L929 cell line. Moreover, the surface roughness, fractal dimension analysis, and texture analysis were calculated. Samples after surface treatment have substantially improved properties compared to the reference SLA (sandblasted and acid-etched) surface. The surface roughness (Sa) was 0.59-2.38 µm, and none of the tested surfaces had cytotoxic effect on NHDF and L929 cell lines. A greater cell growth of NHDF was observed on the tested PEO and PEO-S samples compared to reference SLA sample titanium.

Supporting the Wound Healing Process-Curcumin, Resveratrol and Baicalin in In Vitro Wound Healing Studies.

The purpose of the investigation was to evaluate the effect of the selected bioflavonoids curcumin, resveratrol and baicalin on the wound healing process in an in vitro model. In the study, Balb3t3 and L929 cell lines were used. The first step was the evaluation of the cytotoxicity of the substances tested (MTT assay). Then, using the scratch test (ST), the influence of bioflavonoids on the healing process was evaluated in an in vitro model. The second stage of the work was a mathematical analysis of the results obtained. On the basis of experimental data, the parameters of the Brian and Cousens model were determined in order to determine the maximum value of the cellular and metabolic response that occurs for the examined range of concentrations of selected bioflavonoids. In the MTT assays, no cytotoxic effect of curcumin, resveratrol and baicalin was observed in selected concentrations, while in the ST tests for selected substances, a stimulatory effect was observed on the cell division rate regardless of the cell lines tested. The results obtained encourage further research on the use of substances of natural origin to support the wound healing process.

An Experimental Anodized Titanium Surface for Transgingival Dental Implant Elements-Preliminary Report.

The characteristics such as microtopography, physical and chemical properties influence the behavior of an implant in a soft tissue. Anodization-as a potent method of titanium alloy surface modification-of the transgingival abutment or healing screw, has achieved some improvement. One of the possible surface treatment method is low-pressure radiofrequency oxygen plasma treatment. The aim of the study was to evaluate the chemical properties and cytocompatibility of the experimental surface. Titanium discs made of grade-23 titanium alloy (Ti-6Al-4V) anodized (A sample) with different voltage parameters (28, 67, 78, and 98 V) were included in the study. Half of the samples regarded as the "S" group were additionally treated with low-pressure radiofrequency oxygen plasma treatment. The surfaces were characterized using scanning electron microscopy, X-ray spectroscopy and Raman spectroscopy, and electrochemically investigated via a corrosion test. Furthermore, two cell lines were used, including the CHO-compatible reference line and a primary human fibroblast line for the MTT assay; direct (contact) cytotoxicity of the materials was tested with the cells, and the growth of fibroblasts on the surfaces of the different materials was tested. The morphology of the "S"-treated samples did not differ from the morphology of only-anodized samples. However, the oxygen concentration on the surface in that group slightly increased by about 1% as a result of post-trial treatment. The highest corrosion resistance was observed for both A-78 V and S-78 V samples. The cytotoxicity assay revealed no changes in cell morphology or vitality. The MTT test proved comparable culture viability among all groups; however, the "S" samples showed statistically significantly higher fibroblast proliferation and adhesion scores compared to the "A" samples. Through the in vitro study, the low-pressure radiofrequency oxygen plasma treatment of the anodized Ti-6Al-4V alloy presented itself as an auspicious option in the field of transgingival element surface modification of implants.

Botox Therapy for Hypertrophy of the Masseter Muscle Causes a Compensatory Increase of Stiffness of Other Muscles of Masticatory Apparatus.

Little is known about the nature of masseter muscle hypertrophy. We investigated the masseter muscle stiffness change after a single intra-masseteric session of Botox injections in people with benign bilateral masseter hypertrophy and the effect of the treatment on the stiffness of the temporalis muscle. Stiffness of the muscles was measured with shear-wave elastography at baseline and 3 weeks after Botox injections in 22 otherwise healthy people. Before the treatment, the stiffness of the masseter was lower than of the temporalis muscle (10.18 ± 1.67 kPa vs. 11.59 ± 1.54 kPa; p = 0.002). After the treatment, this difference increased (6.38 ± 1.34 vs. 13.10 ± 1.92; p < 0.0001). The drop in the stiffness of the masseter muscle was symmetrical (left side by 3.78 kPa; right side by 3.83 kPa). No differences between the left and right sides of the face in terms of muscle stiffness were observed. The study shows that Botox injections reduce stiffness of the masticatory muscles which, in turn, increases the stiffness of the temporalis muscles. Due to the knock-on effect of the change in the masseter function on the other masticatory muscles, simultaneous evaluation and treatment of the temporalis muscle may be required to ensure the desired functional and cosmetic effect.

Role of implant loading time in the prevention of marginal bone loss after implant-supported restorations: A targeted review.

The implant-supported restoration of missing teeth is a recognized method of treatment that ensures a functional, esthetic and durable effect, along with patient satisfaction. However, the preferable time of dental implant loading is under debate. Currently, 3 protocols are used: immediate loading; early loading; and conventional (late) loading. Immediate loading provides benefits such as short treatment time, the elimination of the second surgery required for later loading protocols, the protection of the gingival papilla, an immediate esthetic effect, and high patient satisfaction. This review aimed to summarize the evidence on the impact of loading time on marginal bone loss (MBL) around dental implants, which is considered a useful measure of implantological treatment effects. A literature search was conducted based on the PubMed/MEDLINE database. The search focused on studies providing the MBL values by protocol. Out of the 1,366 hits received in the initial search, 10 studies were included in the qualitative analysis. At 12 months, the MBL range was 0.17-1.86 mm in patients undergoing the immediate protocol, 0.14-1.22 mm in patients undergoing the early protocol, and 0.44-0.91 mm in patients undergoing the late protocol. The studies were heterogeneous, but no significant differences in the occurrence of MBL were reported between the immediately and early loaded implants as compared with the conventionally loaded ones. Further studies are needed to determine other factors that might be related to the type of protocol, important for optimal patient treatment.

Fractal Dimension and Texture Analysis in the Assessment of Experimental Laser-Induced Periodic Surface Structures (LIPSS) Dental Implant Surface-In Vitro Study Preliminary Report.

Laser-induced periodic surface structures (LIPSS) are the sub-wavelength periodic nanostructures generated by the femtosecond laser. Implant topography and its nanostructural changes can be important for biomedical applications. In order to compare the surface topography of different implants, appropriate mathematical and physical descriptive methods should be provided. The aim of the study was to evaluate the experimental LIPSS-based-Low Spatial Frequency LIPSS (LSFL) dental implant surfaces. Novel methods of surface analysis, such as Fractal Dimension Analysis and Texture Analysis, were compared to the standard surface roughness evaluation. Secondary, cell viability, and attachment tests were applied in order to evaluate the biological properties of the new titanium surface and to compare their correlation with the physical properties of the new surfaces. A Normal Human Dermal Fibroblast (NHDF) cytotoxicity test did not show an impact on the vitality of the cells. Our study has shown that the laser LIPSS implant surface modifications significantly improved the cell adhesion to the tested surfaces. We observed a strong correlation of adhesion and the growth of cells on the tested surface, with an increase in implant surface roughness with the best results for the moderately rough (2 µm) surfaces. Texture and fractal dimension analyses are promising methods to evaluate dental implants with complex geometry.

Aesthetic Outcomes of Early Occlusal Loaded SLA Dental Implants with Hydroxyl Ion Modified Surface-A 12 Months Prospective Study.

BACKGROUND: Many efforts have been made recently to arrange a newer, more hydrophilic and more osteoconductive implant surface. One of the possible options in this matter is modification with hydroxyl ion. MATERIALS AND METHODS: Forty implants with the diameters 3.5 and 4.0 mm were inserted as a single missing tooth restoration protocol in the frontal aspect of the maxilla. All implants were loaded early in a 4 week period. Prior to and during the surgery, the following indices were considered: height of keratinized tissue, the thickness of soft tissue, and the initial level of bone tissue. After 12 months, the implant and the tissues in its direct vicinity were evaluated once more with the following indices: marginal bone loss (MBL), height of keratinized tissue (HKT), probing pocket depth (PPD), pink and white aesthetics scores (PES, WES), as well as pain sensations combined with the procedure (VAS). All results were related to the diameter of the implant and thickness of periodontal biotype. RESULTS: High aesthetic outcomes were reported regardless of soft tissue thickness and implant diameter. The VAS score was higher for the 4.0 implant group, and the thickness of soft tissue had no influence on VAS. In case of implantation in thin or soft tissue, higher MBL levels were reported (0.26 mm), while in case of a thick phenotype, MBL was 0.06 mm. CONCLUSIONS: Hydrophilic surface implants can be used for a protocol of early functional occlusal loading. The initial thickness of soft tissue does not influence aesthetic outcomes and does not raise pain perception, although it may elevate crestal bone resorption.

PRF versus xenograft in sinus augmentation in case of HA-coating implant placement: A 36-month retrospective study.

BACKGROUND: Sinus lift with a simultaneous implant placement in the residual maxilla is a common technique used worldwide. Nevertheless, choosing an ideal grafting material remains an object of dispute. The use of an autologous blood-derived graft, known as platelet-rich fibrin (PRF), has not yet been recognized to be as good as xenografts and alloplastic materials. However, initial results have been promising. OBJECTIVES: To conduct a clinical and radiological comparison of implantation with a simultaneous sinus lift using xenograft or PRF clots. MATERIAL AND METHODS: Thirty sinus lifts with simultaneous implantation were conducted using a lateral window approach and the tent pole technique, with xenograft (group 1 (G1)) or PRF (group 2 (G2)) as a filling material. To be included in the study, patients must have had an alveolar ridge height of 4-5 mm, no signs of inflammatory processes, good oral hygiene, and no other grafting procedures performed in region of implant insertion. In each case, the measurements taken were probing pocket depth (PPD), height of keratinized tissue (HKT), clinical attachment level (CAL), recession depth/width (RD/RW), and, on panoramic X-rays, marginal bone loss (MBL), grafted sinus high (GSH), and bone gain (BG). Preand post-operative treatment was applied to reduce the chance of infection. RESULTS: During the study, 30 implants (hydroxyapatite-coated implants manufactured by SGS - 10 mm in length and 4.2 mm in diameter) were placed. The survival rate of implants in both groups was 100% with no implant mobility, pain, paresthesia, or inflammatory processes in the direct vicinity of the implants observed, except in 1 patient. After 36 months of follow-up, the radiological assessments for G1 were: GSH 4.5 mm, MBL 0.46 mm and BG 4.53 mm; and for G2: 3.4 mm, 0.6 mm and 3.4 mm, respectively. Results of the clinical measurements were for G1: HKT after 36 months (HKT36) 2.46 mm, CAL 0.47 mm and PPD 2 mm; and for G2: HKT36 3.13 mm, CAL 0.6 mm and PPD 2.07 mm. CONCLUSIONS: After 3 years of follow-up, the results of sinus lifting solely using PRF with simultaneous implantation were promising, especially in terms of soft tissue management. Therefore, PRF can be regarded as an alternative to previously used materials.

Short (6 mm) and Regular Dental Implants in the Posterior Maxilla-7-Years Follow-up Study.

Short 6 mm dental implants are considered as an alternative to the maxillary sinus elevation and bone augmentation procedure where there is a reduced alveolar ridge height. The aim of this study was to compare the implant survival rate between short dental implants (6 mm) and regular length implants (11-13 mm) when placed in combination with bone grafting and loaded with a single non splinted crown, seven years after placing the implant. It was conducted as a controlled clinical study of 30 patients with partial edentulism in the posterior maxilla. The protocol included radiological and clinical evaluation of the C/I ratio (length of the superstructure divided by the length of the implant crestal part), marginal bone level (MBL), ultrasonography measurement of soft tissue surrounding implant (STT), patient-reported outcomes, and biological and technical complications. A total number of 28 implants (93%) remained integrated during follow-up period. MBL of 0.50 and 0.52 mm was observed for short implants and regular implants, respectively. MBL was checked for correlation with STT, and a negative correlation was found between MBL: STT. Our study has demonstrated a significantly lower implant survival rate for short implants compared to regular implants (87% compared to 100%). Despite the loss of several implants, good clinical results were achieved in the remaining implants in both groups. It is, therefore, worth considering short implants as an alternative to regular implants with a sinus lift surgery.

Proanthocyanidins and Flavan-3-Ols in the Prevention and Treatment of Periodontitis-Antibacterial Effects.

Flavan-3-ols and their oligomeric forms called proanthocyanidins are polyphenolic compounds occurring in several foodstuffs and in many medicinal herbs. Their consumption is associated with numerous health benefits. They exhibit antioxidant, anti-inflammatory, cytoprotective, as well as antimicrobial activity. The latter property is important in the prevention and treatment of periodontal diseases. Periodontitis is a multifactorial polymicrobial infection characterized by a destructive inflammatory process affecting the periodontium. Using non-toxic and efficient natural products such as flavanol derivatives can significantly contribute to alleviating periodontitis symptoms and preventing the disease's progress. Therefore, a comprehensive systematic review of proanthocyanidins and flavan-3-ols in the prevention and treatment of periodontitis was performed. The present paper reviews the direct antibacterial effects of these compounds against periodontic pathogens. The immunomodulatory effects, including animal and clinical studies, are included in a separate, parallel article. There is significant evidence supporting the importance of the antibacterial action exerted by proanthocyanidins from edible fruits, tea, and medicinal herbs in the inhibition of periodontitis-causing pathogens.

Proanthocyanidins and Flavan-3-ols in the Prevention and Treatment of Periodontitis-Immunomodulatory Effects, Animal and Clinical Studies.

This paper continues the systematic review on proanthocyanidins and flavan-3-ols in the prevention and treatment of periodontal disease and covers the immunomodulatory effects, and animal- and clinical studies, while the other part discussed the direct antibacterial properties. Inflammation as a major response of the periodontal tissues attacked by pathogenic microbes can significantly exacerbate the condition. However, the bidirectional activity of phytochemicals that simultaneously inhibit bacterial proliferation and proinflammatory signaling can provide a substantial alleviation of both cause and symptoms. The modulatory effects on various aspects of inflammatory and overall immune response are covered, including confirmed and postulated mechanisms of action, structure activity relationships and molecular targets. Further, the clinical relevance of flavan-3-ols and available outcomes from clinical studies is analyzed and discussed. Among the numerous natural sources of flavan-3-ols and proanthocyanidins the most promising are, similarly to antibacterial properties, constituents of various foods, such as fruits of Vaccinium species, tea leaves, grape seeds, and tannin-rich medicinal herbs. Despite a vast amount of in vitro and cell-based evidence of immunomodulatory there are still only a few animal and clinical studies. Most of the reports, regardless of the used model, indicated the efficiency of these phytochemicals from cranberries and other Vaccinium species and tea extracts (green or black). Other sources such as grape seeds and traditional medicinal plants, were seldom. In conclusion, the potential of flavan-3-ols and their derivatives in prevention and alleviation of periodontal disease is remarkable but clinical evidence is urgently needed for issuing credible dietary recommendation and complementary treatments.

Antimicrobial Efficacy of Different Decontamination Methods as Tested on Dental Implants with Various Types of Surfaces.

BACKGROUND Peri-implantitis is an inflammatory reaction affecting both hard and soft tissues surrounding dental implants. This pathological condition is caused by a polymicrobial aggressive biofilm that colonizes the implant and abutment surface at the peri-implant crevice level. The present in vitro study evaluated different methods of implant surface decontamination and assessed whether the type of the implant surface influences the results. MATERIAL AND METHODS The study was conducted in an in vitro model of peri-implantitis using 30 implants. The implants were divided into 3 equal groups based on the surface characteristics: machined-surface, sand-blasted and acid-etched, and HA-coated. Implants were coated with E. coli biofilm. After an incubation period, they were decontaminated with 4 different methods: sonic scaler application, sonic scaler application with the chemical agent Perisolv® combination, Er: YAG laser treatment, and PDT therapy with methylene blue as a photosensitizer. RESULTS The highest level of decontamination was achieved for machined-surface implants and for the combined chemical-mechanical and Er: YAG laser treatment. CONCLUSIONS The results of our study suggest that the method of implant decontamination should be customized to the type of implant surface.

Evaluation of the three methods of bacterial decontamination on implants with three different surfaces.

BACKGROUND: The main goal of the treatment of the peri-implantitis is to decontaminate the surface of the implant, thereby enabling further treatment involving, e.g., guided bone regeneration. Since new implants of the rougher surface were introduced to the common dental practice, decontamination is even more difficult. OBJECTIVES: The aim of the study was to evaluate 3 different methods of decontaminating implants with 3 different surfaces. MATERIAL AND METHODS: A total of 30 dental implants with 3 different surface types (machined, sandblasted, and acid-etched (SLA) and hydroxyapatite (HA)-coated) were used in the study. Each group of implants was coated with Escherichia coli biofilm and cultivated. Afterwards, the implants were transferred to the jaw model and treated with a different method: sonic scaler mechanical debridement with a Woodpecker PT5 sonic scaler (1st group), and mechanical debridement with sonic scaler and with the combination with chemical agent Perisolv® (2nd group), and with Er:YAG laser treatment (3rd group). Each implant was treated with the specific method and sent for further microbiological evaluation. RESULTS: The highest level of decontamination was achieved for machined-surface implants and the lowest for HA-coated implants. The method with the highest biofilm reduction was the scaler and Perisolv® group. The highest level of decontamination of HA-coated implants were achieved for Er:YAG laser irradiation method. CONCLUSIONS: In the following paper, the superiority of combined chemical-mechanical method of decontaminating the surface of the implant on SLA and machined-surface implants was proved. On the contrary, Er:YAG laser irradiation was reported as the best option for decontamination of the HA-coated implants. In our opinion, it is a significant finding, revealing that the method of peri-implantitis management should be considered in accordance to the type of the surface of the implant (customized to the surface of the implant).

Chemical Composition of East Asian Invasive Knotweeds, their Cytotoxicity and Antimicrobial Efficacy Against Cariogenic Pathogens: An In-Vitro Study.

BACKGROUND Giant knotweeds originating from East Asia, such as Reynoutria japonica, and Reynoutria sachalinensis, and their hybrid such as Reynoutria x bohemica, are invasive plants in Europe and North America. However, R. japonica is also a traditional East Asian drug (Polygoni cuspidati rhizoma) used in Korean folk medicine to improve oral hygiene. The aim of this study was to evaluate the antibacterial activity of acetone extracts of Reynoutria species against dominant caries pathogen such as Streptococcus mutans and alternative pathogens, as well as characterize the phytochemical composition of extracts and examine their cytotoxicity. MATERIAL AND METHODS Ultrasonic extraction was used to obtain polyphenol-rich extracts. The extracts were characterized by HPLC-DAD-ESI-MS. To test bacterial viability, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against S. mutans, S. salivarius, S. sanguinis, and S. pyogenes were determined. The cytotoxicity of the extracts to human fibroblasts derived from gingiva was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. RESULTS The R. japonica extract had the highest bacteriostatic and bactericidal activity against pathogens causing caries, mainly dominant caries pathogen S. mutans (mean MIC 1000 µg/mL and MBC 2000 µg/mL), which was most likely associated with a higher content of stilbene aglycons and anthraquinone aglycons in the extract. Moreover, the R. japonica extract demonstrated the lowest cytotoxic effect on human fibroblasts and exhibited cytotoxic activity only at the concentration causing the death of all S. mutans. CONCLUSIONS The results indicate that the R. japonica acetone extract can be considered as a natural, antimicrobial agent for caries control.

Short Implants and Conventional Implants in The Residual Maxillary Alveolar Ridge: A 36-Month Follow-Up Observation.

BACKGROUND Short dental implants are considered an alternative method of treatment to the maxillary sinus elevation and bone augmentation procedure at the sites of a reduced alveolar ridge height. The aim of the study was to determine the most effective therapeutic approach for a single tooth replacement in a reduced maxillary alveolar crest. MATERIAL AND METHODS We enrolled 30 partially edentulous patients having a residual crestal height of 6 mm and a minimal width of the alveolar ridge of 6-7 mm: 15 patients received regular dental implants (OsseoSpeed™ L11 Ø4 mm and L13 Ø4 mm) and the implantation was preceded by the sinus lift procedure from a lateral window approach with the application of a xenogeneic bone graft, whereas the remaining 15 patients received short implants (OsseoSpeed™ L6 mm Ø4 mm) without the sinus lift and augmentation procedure. All implants were loaded with single non-splinted crowns. Radiological examination (CBCT, RVG) was performed before the surgery and after 36 months. Primary and secondary stabilization with Osstell ISQ® and Periotest® were assessed. RESULTS Good results in primary and secondary stability were achieved in both systems. The marginal bone level (MBL) loss was low (0.22±0.46 mm and 0.34±0.24 mm, for short and conventional implants, respectively). No significant difference in MBL between groups was found. CONCLUSIONS Short implants can be successfully used to support single crowns in the lateral part of the maxilla.

Application of fractal dimension analysis and photodynamic diagnosis in the case of differentiation between lichen planus and leukoplakia: A preliminary study.

BACKGROUND: Photodynamic therapy (PDT) is a noninvasive method for the treatment of premalignant lesions, such as leukoplakia and lichen planus (LP). These lesions are very irregular. In the case of such irregular lesions, fractal dimension analysis (FDA) is very helpful. Photodynamic diagnosis (PDD) enables the visualization of irregular lesion shapes more precisely than a classical white-light examination. OBJECTIVES: In our study, we tried to distinguish oral leukoplakia and LP, using FDA in a classical examination with white light and PDD. Lesions treated using PDT were histopathologically verified. MATERIAL AND METHODS: We enrolled 35 patients in our study. Fractalyse software v. 2.4 (University of Franche-Comté, Besançon, France) was used to count fractal dimensions (FDs). Photodynamic therapy and PDD were mediated with 20% delta-aminolevulinic acid (5-ALA). RESULTS: Fractal dimensions of leukoplakia foci of the tongue in a white-light examination were significantly lower than in PDD. In the case of LP, a significant difference of FDs was observed between lesions in the cheek and in the alveolar ridge region. Differences in FDs were observed between leukoplakia foci of the alveolar ridge, tongue and palate. A complete response of leukoplakia foci to PDT was observed in 10 out of 34 lesions, partial remission occurred in 20 lesions and a total lack of response was noted in 4 lesions. Generally, LP was completely treated in 7 out of 14 cases, a partial response was observed in 5 lesions and a failure of PDT treatment was noted in 2 cases. CONCLUSIONS: Fractal dimension analysis may be a useful method in the comparison of complicated shapes of such lesions as LP or leukoplakia, but our study did not confirm that this method may be used to distinguish LP and leukoplakia without a histopathological examination. Photodynamic therapy is an effective treatment method in the case of LP and leukoplakia of the oral cavity.

Fractal dimension analysis a supplementary mathematical method for bone defect regeneration measurement.

AIM OR PURPOSE: The geometry of a bone defect is very complex. Its shape is too complicated to measure or compare with other bone defects using only traditional measuring methods Traditional measuring techniques based on the histomorphometric analysis of a bone specimen require supplementary measuring. For the fractal dimension analysis (FDA) mathematic formulas are used to describe complicated and chaotic shapes. The FDA offers a possibility of a comparison between complicated and complex shapes such as a histological image of a bone defect. The aim of this study was to evaluate the FDA of bone defects as a supplementary method for a defect regeneration assessment. MATERIALS AND METHODS: For the purpose of this study, microscopic photographs of bone specimens stained with hematoxylin and eosin obtained during a block biopsy were used. The bone blocks used in this study were obtained during a rat animal model study. Specimens were collected from 36 Wistar rats where a cranial defect was created and augmented with five different novel biomaterials and compared to the unfilled defect in the control group. New bone formation in every specimen was histomorphometrically measured by two independent operators and compared to FDA measurements. RESULTS: Both traditional and FDA techniques have shown statistically significant differences between bone formation in test groups compared to the control one; on the other hand, no statistically significant difference was found between other groups. The Pearson's r-test was conducted to measure the linear dependence (correlation) between standard measurements and the FDA, and a positive linear correlation was found -r=0.94. CONCLUSIONS: The FDA can be used as a supplementary method for bone regeneration measurements.

Osseointegration of zirconia implants with 3 varying surface textures and a titanium implant: A histological and micro-CT study.

BACKGROUND: Zirconium - a bioinert metal - in comparison with titanium implants, offers a variety of potential advantages for use in the esthetic area of dentistry due to its tooth-like color. Zirconium dental implants are considered to be an alternative method of treatment to conventional titanium dental implants for patients with a thin gingival biotype. OBJECTIVES: This study was designed to study the bone tissue response to new zirconia implants with modified surfaces in comparison with commercially available titanium dental implants and commercially available zirconia implants. MATERIAL AND METHODS: The study was carried out on a group of 12 16-month-old minipigs. New zirconia implants with 3 different surfaces were used: M1 - blasted surface, M2 - etched surface and M3 - blasted and etched surface (Maxon Motor GmbH, Sexau, Germany) and compared to conventional titanium implants with an sandblasted and acid etched (SLA) surface (Straumann GmbH, Freiburg, Germany) and commercially available zirconia implants (Ziterion GmbH, Uffenheim, Germany). Histological and micro-computed tomopgraphy (micro-CT) evaluation was performed. RESULTS: In the micro-CT assessment, the average bone-implant contact (BIC) of the zirconia experimental implants was 41.44%. In particular, the BIC% for M1 was 39.72%, for M2 it was 43.97%, and for M3 - 40.63%; in the control group it was 49.63% and 27.77% for ceramic and titanium control implants, respectively. The intra-group analysis showed no statistically important differences between the BIC values for implants in any group. However, the analysis of BIC for different regions of the same implant showed statistically significant differences in all of the groups between the results of the threaded region and the neck and the apex. CONCLUSIONS: The results of our study suggest that zirconia implants with modified surfaces display features of osseointegration similar to those of titanium implants. These results are promising in using zirconia implants for dental applications in the future.

Zirconium: The material of the future in modern implantology.

The authors present the contemporary state of knowledge concerning alternative materials for dental implantology. First of all, factors influencing osseointegration are stated. The most important factors seem to be the type of implant surface. Among the numerous parameters describing them, the most important are: average roughness and porous density. Some studies proved that materials with comparable surface roughness provide similar osseointegration. In modern implantology titanium is the material still considered as a "gold standard". However, aesthetic features of titanium still bear several disadvantages, especially in the case of periodontium with a thin biotype in the anterior, aesthetic sensitive area of the jaw. If a titanium implant is used in such a case, the mucosa at the implant's neck may become grayish and, consequently limits the success of the overall treatment. That was the reason for seeking alternative materials to manufacture dental implants. Initiated by general medicine, mainly orthopedics, the search led to the discovery of zirconium dioxide used in dental implantology. A small number of complications, good chemical parameters, anticorrosion, mechanical strength, elasticity module close to the one of steel, and especially biocompatibility made zirconium a perfect material for this purpose, although this material presents several problems in achieving optimal roughness. In this overview one of the probable methods, a process of partial synterization, is presented.