Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1) application of calcium phosphate into various fields in dentistry; (2) improving mechanical properties of calcium phosphate; (3) biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields.

Due to an increasing interest in esthetics and concerns about toxic and allergic reactions to certain alloys, zirconia was proposed as a new ceramic material in the later part of 20 th century. It has become a popular alternative to alumina as biomaterial and is being used in dental applications for fabricating endodontic posts, crown and bridge restorations and implant abutments. It has also been applied for the fabrication of esthetic orthodontic brackets. This article presents a brief history, dental applications and new methods for fabrication of zirconia improving its mechanical properties. Additionally, the bonding between zirconia and resin cements as well as conventional cementation has been discussed. The methods of the improvement of the bonding strength have also been highlighted.

This study aimed to analyse and compare the stability of two dental posts cemented with four different luting agents by examining their shear stress transfer through the FEM. Eight three-dimensional finite element models of a maxillary central incisor restored with glass fiber and Ni–Cr alloy cast dental posts. Each dental post was luted with zinc phosphate, Panavia resin, super bond C&B resin and glass ionomer materials. Finite element models were constructed and oblique loading of 100 N was applied. The distribution of shear stress was investigated at posts and cement/dentine interfaces using ABAQUS/CAE software. The peak shear stress for glass fiber post models minimized approximately three to four times of those for Ni–Cr alloy cast post models. There was negligible difference in peak of shear stress when various cements were compared, irrespective of post materials. The shear stress had same trend for all cement materials. This study found that the glass fiber dental post reduced the shear stress concentration at interfacial of post and cement/dentine compared to Ni–Cr alloy cast dental post.

Aim: To assess the root canal filling quality performed by general dental practitioners in Yemen through radiographic evaluation. Materials and Methods: Four hundred fifty-five digital panoramic radiographs were selected from the archive of the Dental Health Center in Sana'a, Yemen. The final sample consisted of 221 patients, 685 teeth, and 977 root canals. The criteria for overall radiographic adequacy of root canal fillings were defined as the presence of adequate length, density and taper, and absence of iatrogenic errors (ledges, transportations and perforations). Chi-square test was used to determine statistical significance between different parameters. Results: This study considered only radiographic criteria for evaluation of the root canal fillings. The percentage of root canal fillings with adequate length, density and taper was 30.8%, 29.6% and 20.7%, respectively. Considering the incidence of iatrogenic errors, perforations were present in 12 root canals (1.2%), while the presence of transportations was observed in 20 root canals (2.0%). However, ledges were no detected in any root canals. Conclusion: The root canal filling quality performed by general dental practitioners in Yemen is poor.

Determination the dental arch dimensions in human populations is necessary for various fields of dental sciences. This study was designed to evaluate the maxillary dental arch dimensions of Yemeni children aged (10-12) years. The sample was gathered from primary and intermediate school in Sana'a city, Yemen. Clinical examination was performed on 200 subjects (100 males and 100 females) that fulfillment the criteria of this study. The examination was carried out for subjects that have either normal occlusion or class I with anterior dental crowding. Pairs of studying models for the dental arch was constructed and evaluated by special software for digitizing and analyzing the data. This study reported that class I with anterior dental crowding is still high incidence, particularly for females, in Yemeni Population. Therefore, more prevention protocols and dental health educational programs about orthodontics needs are essential in Yemen.