Dental practice today used a lot of different materials. This paper evaluates tribological and mechanical properties of two dental materials CeramX and I-Light. Tribological analysisad of samples was conducted at temperature 37°C and in the environment of artificial saliva. The wear rate was evaluated with a ball-on-disc tribotester, in accordance to ASTM G-133 norm. The counterbodies were 6-mm-in-diameter Al 2 O 3 steel balls. The load of 2, 10 and 20 N was applied. The tests were conducted at 0.15 m/s sliding velocity over a sliding stroke of 1000 m. The changes in the value of the following parameters were measured during the trials: friction coefficient, friction force, temperature and wear depth. After completing the tribological tests the surface of samples was carried out.

Introduction. Color of teeth is undoubtedly one of the most important factors considering patients' satisfaction with the quality of their restoration, especially in the anterior region of the mouth. Therefore, the determination of color is an integral part of esthetic dentistry and therefore it should be given the highest importance in dentistry in order to achieve the esthetic requirements of patients.Aim. The aim of this study was to evaluate tooth color in 3 different ethnic groups and its relationship with gender and type of tooth using a clinical spectrophotometer.Material and methods. A total of 90 dental students of the Medical University of Lublin was divided into three groups of 30 each according to participant's ethnicity, which was as follows: Polish, Saudi Arabian and Taiwanese. Then, different divisions were made according to gender as well as the type of teeth. The tooth color was identified by spectrophotometer. The data was statistically analyzed.Results. For the Vita Classical shade guide, A3.5 shade was the most frequently chosen in Taiwanese and Saudi students' teeth. However, the most common shade observed for the anterior teeth of Polish students was A3. The most common shade among males was A3.5 and in females A3 was the most frequent shade. In all 360 central incisors, overall, the most common shades noticed were A2, D3 and C1. In all 360 lateral incisors, D3, A3 and A2 were the most frequent shades for this group of teeth. In all 360 canines, A3.5 and A3 were the most common shade with almost half of the number of canines in this study was measured with A3.5.Conclusions. Based on the performed preliminary research, it was observed that Polish students tend to have brighter teeth than Saudis which in turn have even brighter teeth than Taiwanese students. It was also noted that men are more likely to have darker shade values than women. Central incisors have higher values of tooth color than lateral incisors and canines.

Sev eral new cal cium sili cate based ma te ri als have been re cently de vel oped [5]. Bio den tine (Sep to dont, France)-"bio ac tive den tin sub sti tute" is a one among them. This is a mod ern den tine re place ment based on Port land ce ment. The ef fect of "bio ac tive den tin sub sti tute" con sists in origi nat ing min er al ized mi cro conec tions be tween the mate rial and den tin tu bules. Bio ac tive na ture of Bio den tine is based on odon to tropic fea tures caus ing for ma tion of ter tiary den tin and den tin bridges. This is the rea son why it is rec om mended in di rect and in di rect pulp cap ping, per fora tions, apexi fi ca tion, re sorp tions, pulp ex po sures and ret ro grade root fill ing. Its wide use and very good physical prop er ties are the best as sets [9,11,12,14]. The main core of the pow der mix ture are sili cates: tricalcium sili cate and di-calcium sili cate. It also con tains cal cium car bon ate and ox ide as filler, iron ox ide re spon si-ble for shade and zir co nium ox ide as ra dio pa ci fier. Adding cal cium chlo ride to the liq uid part ac cel er ates the sys tem and hy dro solu ble polymer com po nent re duces wa ter in the mix ture. The abil ity of cal cium sili cate to inter act with wa ter pro vide set ting and hard en ing of the ce ment. This is a hy dra tion of the tri cal cium sili cate, which pro duces a hy drated cal cium sili cate gel and calcium hy drox ide. This dis so lu tion pro cess oc curs on the sur face of each grain of cal cium sili cate. The hy drated calcium sili cate gel and the ex cess of cal cium hy drox ide tend to pre cipi tate at the sur face of the par ti cles and in the pores of the pow der, due to satu ra tion of the me dium. The precipi ta tion pro cess is re in forced in sys tems with low wa ter con tent. The un re acted tri cal cium sili cate grains are surrounded by lay ers of cal cium sili cate hy drated gel, which are rela tively im per me able to wa ter, thereby slow ing down the ef fects of fur ther re ac tions. The C-S-H gel forma tion is due to the per ma nent hy dra tion of the tri cal cium sili cate, which gradu ally fills in the spaces be tween the tri cal cium sili cate grains. The hard en ing pro cess re sults from the for ma tion of crys tals that are de pos ited in a super satu rated so lu tion [3,13].

Calcium silicate-based materials are interesting products widely used in dentistry. The study was designed to compare the chemical reaction between analyzed two preparates and dentin during cavity lining. In our work, dentinal discs were prepared from human extracted teeth filled with Biodentine and MTA+. The samples were then analyzed by way of SEM, EDS and Raman spectroscopy. The obtained results revealed differences in elemental composition between both materials. Biodentine showed higher activity in contact with dentine. Moreover, the interfacial layer in the tooth filled by Biodentine was wider than that in the tooth filled with MTA+. The applied methods of analysis confirmed that both materials have a bioactive potential which is a promising ability.

De tec tion and moni tor ing of the com plex pro cess of dem in er ali zation and re min er ali sa tion by the den tal car ies is a den tist's chal lenge. Even car ies start ing as a sub surface dem in er ali za tion of enamel, may prog ress to the un der ly ing den tine and, even tu ally, to cavi ta tion of the sur face [14]. Ac cu rate di ag no sis be fore cavi ta tion oc curs would per mit tar geted pre ven tive treat ment, thereby signifi cantly im prov ing den tal health and re duc ing the need for ex pen sive drill ing and fill ing [10]. Con ven tional di agnos tic meth ods in volv ing vis ual in spec tion and the use of sharp den tal ex plorer tools de pend on sub jec tive clini cal crite ria such as color, tex ture, soft ness and re sis tance to re moval. These meth ods are good for the de tec tion of larger or cavi tated le sions. How ever, they are not suit able for the de tec tion of early den tal car ies be cause of poor sen si tiv ity and speci fic ity. Rou tine den tal ra dio graphs also lack the abil ity to de tect early cari ous lesions on enamel sur face. Ap proxi mately 30-40% min eral loss is nec es sary be fore ra dio graphs can de tect the cari ous lesion. It can take a few months or longer for this ex tent of dem in er ali za tion. There fore, bet ter di ag nos tic tools are needed to de tect early cari ous le sions and help pre vent dental cavi ties. Over the last years, vari ous tech niques have been ex plored to ad dress the need for bet ter de tec tion tools to di ag nose early den tal car ies. These tech niques include mag ni fy ing loups, di rect digi tal ra di og ra phy, digi tal im ag ing fiber-optic tran sil lu mi na tion, elec tri cal con ductance, quan ti ta tive light-induced fluo res cence, laser-induced fluo res cence, auto fluo res cence, mul ti pho ton im ag ing, infra red ther mo gra phy, te ra hertz im ag ing, op ti cal co her ence to mo graphy, ul tra sound, Ra man spec tros copy and oth ers [1,2,11,14,15,16]. In spite of nu mer ous stud ies evalu at ing dif fer ent tools with re spect to car ies de tec tion, car ies di agno sis con tin ues to be a chal leng ing task for the den tal prac ti tio ner. Es pe cially oc clu sal car ies is a clini cally dif ficult one due to the com plex mor phol ogy of the fis sure and fossa sys tem and fre quent pres ence of stain ing. Ad di tionally, the ex ten sive use of fluo ride and re min er al iz ing agents seems to de lay cav ity for ma tion. There fore, the ac curate de tec tion in the pre cavi ta tion stages is very im por tant for un der tak ing proper pre ven tive and re stora tive pro cedures and avoid ing un nec es sary treat ment.Among al ter na tive tech niques, meas ure ment of elec trical re sis tance has shown the most prom is ing. Car ies di ag no sis by elec tri cal meas ure ment was in tro duced into den tistry many years ago. Even in 1878, Magi tot's first sug ges tion was to use elec tric cur rent for car ies de tec tion [15]. The method is based on the phe nome non that den tal enamel, con sist ing largely of hy droxy...