Tikrit Journal for Dental Sciences

Studies in a variety of scientific disciplines have experimented with various techniques for recycling and reusing the materials they utilize on a regular basis, in this study suggest to re cycling waste of acetal resin.
Purpose: The purpose of this study was to assess and compare the color change of re-injection acetal resin with different percentages or several times.
Material and Methods: Specimens were prepared with dimensions (20±1 mm in diameter x 0.5 mm in thickness) for color stability test and injection according to the manufacture’s instruction for acetal resin as denture base materials and aesthetic clasp. The first group represent control group with (100% New) and other five groups as experimental groups (group II, group III, and group III) with different percentages between new acetal materials and old acetal materials, while two last groups with several times (group IV and group V) only used old acetal materials. Preparation the ratio between the new material with the old material according to pilot study and the best ratio in this study is 25% new acetal material and 75% old acetal material (group II). The old material is preparation by acetal sprue is collected and cutting by cutter and re-injection with new acetal resin.
Results: Statistically non-significant difference in color change in re-injection acetal resin, when comparing the control group with mean (1.046±0.094) and re-injection groups with means respectively (1.040 ±0.076,0.942±0.115,0.993±0.137, 0.978±0.060, and 0.970±0.098).
Conclusion: Color change was statistically non-significant differences between all studied groups

One of the most promising CAD/CAM approaches is milling denture base materials from highly condensed pre-polymerized resin discs. In an effort to overcome the disadvantages of acrylic resin denture base materials, nano-filler materials have been added as well as denture base chemistry adjusted to strengthen the denture base.This eliminates disadvantages associated with polymerization shrinkage compared to conventional heat-cured acrylic resin. Aim of this study: evaluate the surface roughness of PMMA acrylic resin after strengthening the denture- base by addition of zinc oxide nano-filler material to acrylic resin PMMA with concentration (1%) and compare with milled CAD/CAM and non-modified heat-cured PMMA denture base materials. Materials and methods: thirty specimens of acrylic resin PMMA were prepared and divided into three groups 10 specimens for each groups as follows; Control Group (Group1) without ZnO nanoparticles ; Group (2) with (1%) by weight of ZnO nanoparticles ; Group (3) milled CAD/CAM.Each specimen is of dimension ( 10 x 10 x 3 ) in mm and was fabricated using conventional processing method and milling the CAD/CAM blocks .Results: showed the lowest mean value was recorded by milled CAD/CAM (0.230 Ra) Then the non-significant reduction with mean value (0.312 Ra) by PMMA+ ZnO 1% and highest mean value of surface roughness was recorded by pure PMMA without additive (0.327 Ra).Conclusions: There were significant differences between control group PMMA and milled (CAD/CAM) with slight reduction of surface roughness of PMMA with (1%) Zno nanoparticles.

Aim: This study was assumed to investigate the effect of incorporation of nanoparticles “Titanium Dioxide Nanoparticles (TiO2)” in two different percentages which are 3% and 5% (by weight) on compressive strength and surface roughness of glass ionomer cement (GIC) so to improve the conventional glass ionomer cement properties.
Materials and Methods: the powder of GIC was incorporated with TiO2 nanoparticles at two concentrations: 3% and 5% (w/w). An unmodified conventional GIC used as the control group. Ten specimens of each GIC group were used to study the compressive strength using a Universal Testing Machine. Also, 10 discs from each GIC group were used for surface roughness measurement by using profilometer. one way analysis of variance ANOVA test and Tukey’s test were used to analyze data. Results: Nanoparticles incorporation to GIC lead to improve its compressive strength for both percentages 3% and 5%, Tukey’s test showed a significant increase in compressive strength between nanoparticles incorporated and conventional group. The surface roughness measurement also show significantly improvement in both 3% and 5% nanoparticles groups (p<0.05). Conclusion: GIC with TiO2 nanoparticles.

The Aim: The aim of this research was to investigate how distilled water, tea, coffee, and cola affected the surface roughness of poly ether ether ketone CAD-CAM, 3D printing, and heat cure acrylic resin denture bases at specific intervals (6 ,12days). Materials and Methods: Disk shape 10 mm (diameter) ×2 mm (thickness), manufactured from materials used which were PEEK, 3D printing and heat cure acrylic resin. Total number of samples are n= (75) samples, control samples not immersed in beverage media n= 15, experimental samples immersed in beverage solutions (distilled water, tea, coffee and cola) n=60 for evaluating the surface roughness at (6, 12 and 24 days).Then all collecting data were statically analyzed by spss version 25, by means of descriptive statistics, analysis of variance (ANOVA) and duncan multiple range tests at p ≤ 0.05. The Results: The results revealed a significant increase in surface roughness in all beverage solutions at p ≤ 0.05. Conclusions: All beverage solutions had a negative effect on surface roughness of all experimental materials, the surface roughness increased. cola had the most aggressive effect followed by coffee then tea and distilled water have the least effect

This research was to evaluate the effect of distilled water (D.W.), tea, coffee, and cola on flexural strength of PEEK CAD-CAM, 3D printing and heat cure acrylic resin denture base at different durations (6, 12and 24 days). Material used in this research are PEEK, 3D printing and Heat cure acrylic resin with dimension (64 × 10 × 3.3 ±0.2 mm, ISO 20795- 1:201320) for each tested material. Total number of samples are n= (195) samples, Control samples n=15, experimental samples n=180.The control samples were non immersed in beverage media. The experimental samples were immersed in beverage media (distilled water, tea, coffee, and cola) for evaluating the flexural strength at different time which are (6, 12 and 24 days), then all collecting data were statically analyzed by spss version 25, by means of Descriptive statistics, analysis of Variance (ANOVA) and Duncan multiple range tests at p ≤ 0.05. The beverage solutions had been non significantly decreased the flexural strength and this decreasing worst as the immersion periods increased, the most decreasing in flexural strength of PEEK denture base was achieved in 24 immersion days in cola (252.0960 MPa ±5.19825) followed by coffee (253.4360 MPa ± 6.60975) followed by tea(253.7780 MPa ± 6.44697) followed by distilled water (254.1420 MPa ±7.41318) as comparing with control(260.2420MPa ±5.08412), the most decreasing in flexural strength of 3D printing denture base was achieved in 24 immersion days in cola (103.1680 MPa ±12.26532) followed by coffee (105.4360 MPa ±12.36951) followed by tea (107.4530MPa ±11.47399) followed by distilled water (109.1320MPa ±11.66156) as comparing with control(119.7140 MPa ± 12.25421), the most decreasing in flexural strength of heat cure acrylic resin denture base was achieved in 24 immersion days in cola (118.5640MPa ±13.06764) followed by coffee (122.3640MPa ± 9.78213) followed by tea(123.5600MPa ±14.05144) followed by distilled water (126.3620 MPa ± 11.35254) as comparing with control (134.6420 MPa ± 9.79330) at p ≤ 0.05. All beverage media had been negatively affected the flexural strength of all experimental materials and as the immersion periods increased the affect became worst. The aggressive effect was in cola followed by coffee followed by tea and the least effect was in D.W. beverage media. The worst immersion period was 24 then 12 and 6 days. for all tests use but this affect was non significantly.

Post-heat treatment may enhance mechanical properties of selective laser melting (SLM) Cobalt chromium (Co-Cr) alloys, however it is unknown what duration the heat treatment needs to last and how the rate of cooling impacts the alloy's flexural strength and surface roughness. In this study, SLM Co-Cr alloy specimens were heated at 1150 C for 1 or 6 hours and subsequently cooled by air cooling (AC), furnace cooling (FC), or water quenching (WC). Flexural strength and surface roughness were then tested. Aim of this study: Investigate the effect of heat treatment and different cooling conditions on the flexural strength and surface roughness of SLM Co-Cr alloy specimens. The heat treatment will be conducted at 1150 C for two different durations (1-hour and 6-hours) and under three cooling conditions (AC, FC, and WC). Materials and methods: A total of forty-two rectangular specimens, measuring (34×13×1.5 mm) were manufactured through SLM and divided into seven groups, six specimens for each group as follows: The first group denoted as control with no heat treatment and no cooling applied, second and third groups heated for 1 or 6 hours then cooled in the air (AH-1 and AH-6), fourth and fifth groups heated for 1 or 6 hours and left inside the furnace until they cooled (FH-1 and FH-6), sixth and seventh groups heated for 1 or 6 hours and cooled by water quenching (WH-1 and WH-6). Flexural strength and surface roughness tests were performed on the specimens. A flexural strength value of (2147.33 MPa) was indicated that the control group exhibited the highest flexural strength, whereas the FH-6 group exhibited the lowest flexural strength value (1282.66 MPa). The control group showed the worst surface roughness (1.63 μm) while all other groups demonstrated no significant differences in surface roughness ranging from (0.32 to 0.49 μm) with a slight increase in the 6-hours heated groups. Conclusions: Slow cooling rate inside the furnace affects flexural strength negatively. Therefore, a high cooling rate is recommended to get a better flexural strength. On the other hand, surface roughness results suggests that 1-hour is better than 6-hours in terms of heat treatment duration and time saving.

This study aimed to evaluate the impact of surface treatment (polishing, polishing with diamond paste and glazing) on the Vickers microhardness of pressable ceramics IPS Emax porcelain in comparison with non-treated surface. Materials and Methods: Forty disc shaped samples of baseplate wax with 10 mm diameter and 2 mm thickness have been prepared. They were invested and lost wax technique was performed to fabricate the pressable ceramic. Following pressing, they were divided randomly into four groups (n=10): Group A: no surface treatment, Group B: glazing (paste, HT, Ivoclar,Vivadent, Germany) glazing (paste, HT, Ivoclar,Vivadent, Germany), Group C : polishing with burs (DIAPRO TWIST,EVE, GmbH, Germany) and diamond paste (All in one, RENFERT, GmbH, Germany), and Group D: polishing with burs (DIAPRO TWIST,EVE, GmbH, Germany). For all specimens, the Vickers hardness number (VHN) was determined using a digital tester. Vickers hardness was used in this analysis due to the small specimen size and multiple compositions. Each specimen was put on the device's stage, the Vickers indenter was then lowered slowly until it came into contact with the polished surface of the specimen. Results: The highest Vickers Hardness Number was for polishing with burs and diamond paste and polishing with burs, while the lowest Vickers Hardness Number was for control group. One-way ANOVA test showed a high significant difference at P < .000. LSD test reviled there was non-significant difference between polishing with burs and polishing with burs and diamond paste. Conclusions: Within the limitation of the present study, it can be concluded that, polishing can considered as an effective method as glazing to improve surface hardness of pressable ceramic, and polishing with or without diamond paste can be an effective method to improve surface hardness.

Bone morphogenetic protein-2 (BMP-2) has a significant function in the formation of cartilage and bones. Notably, dosing of only BMP-2 protein intravenously is ineffective. Persistent transportation of the stabilized BMP-2 through a carrier has been seen to be essential for enhancing the osteogenesis impact of BMP-2. The current research built a new system of drug delivery by utilising cockle shell derived calcium carbonate nanoparticles (CaCO3NPs) and studied the efficacy of the delivery system on the recombinant human bone morphogenetic protein (rhBMP-2). rhBMP-2-CaCO3NPs nanoparticles were synthesised by means of a modest precipitation procedure along with mechanical grinding. Fourier-transform infrared spectroscopy, UV–Vis spectrophotometer, scanning electron microscope, X-ray powder diffraction, transmission electron microscope, and zeta potential were utilised for characterising the conjugated rhBMP-2-CaCO3NPs. Cytotoxicity of rhBMP-2, CaCO3NPs and rhBMP-2-CaCO3NPs was studied by utilising methylthiazol tetrazolium assay against fibroblast (Rat-1) cells in comparison to rhBMP-2 and CaCO3NPs. The outcomes signified bio-stability of CaCO3NPs and lower toxicity for Rat-1 cells. In summary, CaCO3NPs were prepared by a simple precipitation process. The ensuing nanoparticles could competently entrap rhBMP-2 and generated stable rhBMP-2-CaCO3NPs. A sustained discharge of rhBMP-2 from the CaCO3NPs was seen. CaCO3NPs loaded with rhBMP-2 demonstrated reasonable bio-compatibility. The outcomes indicated that CaCO3NPs may have significant ability as carrier of therapeutic proteins within bone tissue engineering.

Background: The main disadvantage of soft liners is the low thermal conductivity between the denture base and soft liner material. Aim: The present study aims to estimate the impact of adding virgin coconut oil (1.5% vol and 2.5% vol) to a soft acrylic liner material in a thermal conductivity test. Material and Methods: For this project, we did 30 pieces of acrylic soft liner material. The specimens were divided into three groups: 10 control group specimens that only contained the soft liner material, 10 specimens mixed with virgin coconut oil at a volume of 1.5% with the soft liner material, and 10 specimens mi xed with virgin coconut oil at a volume of 2.5% with the soft liner material. Equipment in the Technologies, Department used to conduct thermal conductivity tests. 40mm diameter and 2.5mm thickness thermal conductivity sp ecimens were prepared. Results: Using static analysis, data showed that the soft liner with the highest t hermal conductivity contained virgin coconut oil at a volume of 2.5% compared to the soft liner containing virgin coconut oil at a volume of 1.5%, and the control group, the res ults revealed p < 0.01. Conclusion: Thermal conductivity is increased when virgin coconut oil (2.5% by volume) is incorporated into the soft acrylic liner material.

The effectiveness of fluoride-releasing materials in preventing caries is proportional to the concentration and duration of the fluoride ions they release. The goal of this study was to evaluate the fluoride ion release of two alkasite materials; Cention Forte and Cention-N in comparison to Glass Ionomer Cement (GIC) R iva at two time intervals (24 hours and 7 days) when they are bonded and non-bonded to tooth structures. Methodology: 72 samples were fabricated from the three types of fluoride releasing materials. 36 samples were bonded to teeth specimens (three bonded groups) and another 36 samples were constructed within a silicon mould (three non-bonded groups), each group consisted of 12 samples. The bonded groups were: BCF using Cention Forte, BCN using Cention N and BGI using GIC Riva. The non-bonded groups were: NBCF using Cention Forte, NBCN using Cention N and NBGI using GIC Riva. 5ml of deionized water was used as the storage medi a for all the samples. Fluoride ions measurements were performed by fluoride ion selective electrode at two time intervals; after 24 hours (immediate) and after 7 days (delayed) for all the groups. The mean values of the data were analyzed statistically using one-way ANOVA, Post hoc Tukey's HSD test and paired t-test at p≤0.05. Results: For both bonded and non-bonded groups, at 24h the initial fluoride release of GIC Riva was significantly higher (p=0.00) than both Alkasite groups. While after 7 days, the highest amount of fluoride ion release was recorded for BCF with significant difference with BCN (p=0.016) and BGI (p=0.006), respecti vely. Similarly, NBCF released significantly higher amount of fluoride ions than NBCN and NBGI (p=0.00). The results of paired t-test showed that the mean values of fl uoride ions release was significantly increased from the first 24 to 7 days for all the groups (p≤0.05). Conclusion : The immediate fluoride ions release was highest from GIC Riva. While the delayed fluoride ions release was highest from both Alkasite filling materials for both the bonded and non-bonded groups.

The goal of this research was to determine the surface hardness of heat cure acrylic resin reinforced with Nano Al2O3 after polishing with various materials. Materials and methods: - The 70 rectangular samples were made of a pink impact resistant thermoset acrylic (Vertex, Implacryl, The Netherlands) (65mm long x 10mm diameter x 3mm thick). Following polishing with each material (pumice stone, diamond suspension, colloidal silica), the surface roughness of each sample was determined using the Profilometer surface roughness instrument. The sample surface was glued to the profiler's horizontal base in a very flat position, and the stylus (the profiler's needle) was moved across each sample surface three times in three different directions over a distance of 1.7 mm. were separated into (7) groups were determined by the concentration of Nano powder, Group (A) Control without adding Nano filler of (Al2O3) (10) specimens, Group (B) Polishing with pumice Al2O3 (1%) (10) specimens, Group (C) Polishing with pumice Al2O3 (1.5 %) (10) specimens, Group (D) Polishing with Colloidal Al2O3 (1%) (10) specimens, Group (E) Polishing with Colloidal Al2O3 (1.5%) (10) specimens, Group (F) Polishing with Diamond Al2O3 (1%) (10) specimens, and Group (G) Polishing with Diamond Al2O3 (1.5%) (10) specimens. Data were statistically analyzed using statistical package for social science (SPSS), and the (ANOVA) test is used to determine whether the statistical hypothesis is true. Results: - For the hardness readings the higher mean value of hardness test found in group(D) (1%) polished by colloidal silica (82.74), then group (F)(1.5%)polished by colloidal(82.18), then group (F)(1%)polished by diamond( 81.12), then group(G)(1.5%)polished by diamond( 80.62),then group(C)(1.5%)polished with pumice(80.34),then group(B)(1%) polished with pumice(80.2),then at least group (A)control(80.18). Each of the three groups had a statistically significant difference with Highly sign. (P<0.01). Conclusions: -Specimens of acrylic reinforcement with adding 1.5% of Nano AL2O3 and polished with (colloidal silica, diamond suspension, and pumice, respectively) sequentially showed highly surface hardness then followed group (1%) low surface hardness then group control.

The purpose of present study is to evaluate and comparison the effect of different milling technique surface of CAD/CAM for milled Co-Cr alloy specimens. Material and Methods: The diagnostic divides 20 disc-shaped specimens into 2 main groups, each consisting of 10 specimens for Co/Cr alloys according to their construction, the material used in hard milling and soft milling. All samples for further examination were prepared as drilled discs (diameter 15 mm, height 3 mm) whose surfaces were then finished and polishing with a diamond polisher. Scanning electron microscopy (SEM) images with energy-dispersive beam spectroscopy (EDS) were acquired for one sample in each set to assess the surface topography of the metal framework. All samples were degreased, and steam cleaned samples and heat treated in accordance with the complete firing procedure. Then scanning electron microscopy (SEM) after heating. Samples prepared in the lab for electrochemical corrosion testing were polarized and corroded in accordance with their electrical potential. Results were recorded using Levenes test and anova, with appropriate data analyzed for differences between groups. Results: The results of this study presented that the Descriptive statistics for corrosion test (mmpy) for all experimental groups revealed that the hard milling group mean was the lowest among all groups of the study is recorded (0005), followed, Group soft milling (.0071). The data were statistically analyzed using Welch’s ANOVA and Levene’s test which revealed highly significant differences (p<0.01) among groups. Conclusion: Corrosion resistance decreases in the following order: soft metal milling > hard metal milling, according to the obtained corrosion parameter values.

Fiber-based composite materials have gotten a lot of interest because of their strength, toughness, corrosion resistance, and lightweight. By functionally modifying the fiber components, fiber-based composit e materials can preserve their original qualities while enhancing or overcoming the drawbacks of any single material. Composites constructed from modified fibers are highly suited for usage in a range of industries, including aerospace, high-rise construction, bridge and highway building, and marit ime infrastructure, because of their excellent mechanica l qualities, impact resistance, wear resistance, and fire resistance. Offering a solid sc ientific basis for the synthesis of fiber-based composites a nd their practical applications is the aim of this research.

In the oral environment, the longevity and durability of aesthetic composite resin restorative materials are critical considerations. However, many studies have been done on the effect of certain mouthwashes on the surface hardness and accuracy of composite resin. Therefore, this study aims to examine the effect of GUM® alcohol-free and Listerine alcohol-contained mouthwashes on the surface hardness and dimensional accuracy of cured and dual-cured visible light-cured composite. Methods: Thirty-disc specimens of Nanohybrid light-cured composite resin were prepared according to ISO standardization (4049/2000). The sample was divided into three groups (n=10), the Control non-treated in distilled water; Alcohol-free GUM® and Alcohol-contained Listerine mouthwashes. The surface hardness and dimensional accuracy of specimens were measured at different immersion intervals. These include initial immersion, after one and four weeks, and after the light dual-curing procedure. Data were analyzed via one-way ANOVA (post-hoc Tukey test) performed at a significant P-value of (p ≤.05) and confidence level of 95%. Conclusion: After the dual-curing process, the alcohol-free GUM® mouthwash showed a reduction in the surface hardness of the composite material. Listerine mouthwash had a static reduction in the composite specimen in diameters.

Road traffic accidents (RTAs) are a leading cause of maxillofacial trauma and facial bone fractures. The present study aims to investigate the relationship between facial bone fractures, trauma severity, and the use of seat belts among passengers involved in road traffic accidents in Diyala Governorate, Iraq. To detect the relation of facial bone fractures and severity of trauma in relation to position of passenger and seat belts wearing during road traffic accident in Iraq, Diyala Governorate, especially these Governorate considered the main land road linking the capital and the southern governorates with the governorates of the Kurdistan province. This retrospective study examined patients with facial bone fractures admitted to Baquba Teaching Hospital in Diyala Governorate from October 2020 to September 2022. The study analyzed the data to determine the incidence of facial bone fractures and their severity in relation to the position of the passenger and the use of seat belts during road traffic accidents. Results: A total of 200 individuals were identified as having sustained 464 maxillofacial fractures as a result of road traffic accidents while seated inside a vehicle. The study revealed that the average number of fractures per patient was lowest (0.8 fractures per patient) among front passengers who were wearing seat belts. Drivers who wore seat belts had a slightly higher average number of fractures (2.8 fractures per patient). In contrast, rear passengers who did not wear seat belts had the highest average number of fractures (11 fractures per patient). CONCLUSION: The findings of this study emphasize the significant role of seat belts in reducing the occurrence of facial bone fractures, particularly for drivers and front passengers. In contrast, rear passengers who did not use seat belts were particularly vulnerable to facial bone fractures. These results underscore the importance of seat belt usage as an effective measure to minimize facial bone injuries in road traffic accidents. Further research with more comprehensive details is warranted to strengthen the understanding of the relationship between seat belt usage and facial bone fractures in Iraq.

Background: Recurrent aphthous stomatitis (RAS) is one of the most widespread disorders affecting the oral mucosa, with a prevalence of 50–66%. This study investigated the serum and salivary levels of ferritin between participants with recurrent aphthous ulcers and healthy. Methods: A total of 75 individuals participated in the research separated into three groups, clinically healthy control group (n=25), iron deficiency anemic patient with recurrent aphthous stomatitis (n=25), and iron deficiency anemic patient without recurrent aphthous stomatitis (n=25). The enzyme-linked immunosorbent assay measured the serum and salivary ferritin levels. Result: the serum and salivary levels of ferritin were significantly lower (p<0.05) in anemic groups compared to healthy controls.in the salivary ferritin, there was a statistically significant difference between anemic patients without aphthous ulcer and anemic with aphthous ulcer (p=0.015), while in the serum ferritin, there was non-significant difference. Conclusion: The severity of ferritin deficiency paly as a cofactor for the development and recurrence of recurrent aphthous stomatitis.

Temporo-mandibular joint function has been extensively studied for more despite extensive investigation, the complicated etiology of TMJ dysfunction has remained a mystery for more than a century. Temporomandibular disorder (TMD) is a sub - class of painful orofacial conditions characterized by complaints of pain in the region of the temporomandibular joint (TMJ), difficulty concentrating craniocervicofacial muscles, especially mastication muscles, limitations of mandibular movement, and the presence of articular clicking. Emotional stress, occlusal interferences, tooth loss, postural deviation, muscles of mastication neuromuscular both internal and external dysfunction anomalies in Temporo-mandibular joint anatomy, and the multiple interrelationships between these factors all contribute to the complicated etiology of TMD.
Aim: Determine the prevalence of temporomandibular joint disorder between college students. The sample for this sectional potential study consisted of 691 college students (339 male and 352 female). Self-reported questionnaires were used to determine the incidence and severity of TMJ disorders. By virtue of the quantity and frequency of notable replies, the rankings were upgraded to an intensity ranking. Results:56.6% of students reported some level of TMD, including 39.7% with mild TMD, 12.2% with moderate TMD, and 4.6% with severe TMD. Historically, no significant correlation between gender and TMD severity was observed.
Conclusion: This student population exhibited a high prevalence of TMD; however, the majority of cases were mild. The statistical significance of the association between TMD severity and gender is no longer proven. Despite having TMD. The students had little knowledge of their conditions.

Background: All ceramic CAD/CAM materials require surface treatment protocols varying from one type to another according to their chemical composition, including hydrofluoric acid etching, sandblasting, silica coating, laser etching, and non-thermal plasma treatment. This review's objective to analyze and bring up-to-date data about the surface treatment of ceramics.
Data: The review just searched electronic publications of papers. Websites "Google Scholar" and "PubMed" were utilized as sources for performing data searches using the following keywords: Surface modification, plasma surface treatment, indirect restoration, ceramics The original papers and clinical investigations that were published between the years 2006 to March 2023 that were the most relevant to the subject at hand were chosen.
Conclusion: A variety of surface treatment methods have been proposed to enhance the bonding of restorative materials to resin cement and provide micromechanical retention by altering the restoration's surface mechanically by increasing the degree of roughness or physico/chemically by activating the surface. Hydrophloric acid etch is a golden standard for the surface treatment of feldspathic and lithium disilicate ceramics, the APC concept for zirconia, and hydrofluoric acid or sandblast surface treatment for resin nano-ceramic. A new approach used for surface treatment is plasma treatment, which is really promising in dentistry

At the beginning of orthodontic practice, with fixed appliances, the multi-banding technique of the teeth was used, which had aesthetic disadvantages and often provoked aggression to the gingival tissues. To overcome these unfavorable characteristics, developing the technique of direct bonding of brackets brings the advantages of reducing the cost and time during the treatment and make easier cleaning. The advent of using acid etching in a dental practice which was introduced by Buonocore (Error! Reference source not found.) in 1955, enabling bonding between bracket base and enamel of the teeth. This adhesion had a high impact on esthetic and conservative orthodontics. The advantages of such a direct bonding technique to the tooth surface are reduced the cost and time of overall orthodontic treatment. Additionally, it makes the oral hygiene for the patients more simple and easy. The aims of this paper is to conduct a review of formerly published articles that are dealing with the orthodontic bonding to teeth enamel. It was confirmed that composites resin (CR) beside glass ionomer cement (GIC) are suitable material for such bonding. This could be because of its GIC biocompatibility, fluoride-releasing capacity, as well as lack of acid etching on the tooth surface. In another hand, resin-modified glass ionomer (RMGI) has grown in acceptance among orthodontists. Light polymerized orthodontic adhesives, on the other hand, remain the best adhesives for bracket bonding due to their esthetic and mechanical features, and their use is widespread (Error! Reference source not found., Error! Reference source not found.). In 1958, Sadler (2) recorded the first attempt at direct bonding of orthodontic accessories to the tooth surface. Since the 1960s, studies have been made for improving the procedure in such a way that success in this practice is guaranteed and the use of metallic brackets, directly bonded to enamel. The introduction of acid etching that was presented by Buonocore (Error! Reference source not found.) in 1955 carried out the opportunity of bonding the base of the bracket with the enamel surfaces and create mechanical retentions in the teeth. Thus, from the 1970s onwards, composite resin for bonding orthodontic brackets have been used.

Mastication is a chewing route, that implicates a group of muscles that are responsible for moving the mandible condyle in the temporomandibular joint (TMJ) to chore food between the teeth in the maxillary and mandibular arches (1) .
Regarding the growth of the craniofacial system (CFS),there are an agreement which is strongminded via genetic and ecological aspects (2) . Masticatory forces considered as one of the chief environmental incentives that produce craniofacial difference amongst modern humans. New researeches on a broad variety of creatures, counting those having retro-gnathic post canine teeth, expect that retorts to the force of mastication that determined the superior in the occlusal plane (3) . The effect of masticatory stroke induced by the muscles of the mastication on the development of the morphology of craniofacial portion, has established significant attention in the recent oral invistigations (4) . Meanwhile the skeletal of the CFS adapts to the applied loads by bone remodeling in order to get the optimum formula to resist loads according to Wollf ’s law (5) . CFS has been assumed that it formula is mainly resolute by loading induced by mucsles of mastication. This has been reinforced by numerous clinical and experimental readings (6-9) . Investigational studies displayed that the reduced stresses induced by function on the animals mandibles, whose nourished a lenient diet outcomes in organizational variations in their masticatory systems (10) , in addition to morphological modifications of the lower jaw, like diminished of the alveolar bone size (11, 12) .
Diet could be considered as a element of masticatory magnitude. Recent humans in developed countries eat an additional treated and softer diet rather than old humans. The change from hard to soft nourishment has been join by reduce in mandibular dimension and the growth of the alveolar bone, along with enlarged occurrence of malocclusion (1,5,7

Objectives: The objective of this research was to investigate how boron nitride powder addition in percentages of 1% weight and 1.5% weight, affected the thermal conductivity, transverse strength, and surface hardness of heat cured acrylic resin denture base material. Methods: Ninety specimens were made from heat-cured acrylic resin and then divided into three groups based on the tests: a control group, a reinforced poly methyl methacrylate group with 1% weight boron nitride particles, and a reinforced poly methyl methacrylate group with 1.5% weight boron nitride particles. They investigated into the thermal conductivity, transverse strength, and surface hardness tests. Results: This research showed that 1% and 1.5% weight boron nitride particles significantly increased thermal conductivity and surface hardness in comparison to the controlled group. There was a highly significant increase in transverse strength compared to the control group; at the concentration of 1% weight boron nitride particles. Conclusion: Boron nitride particles enhance the thermal conductivity, transverse strength, and surface hardness when added to heat cure acrylic resin denture base material.