Dr.Rayyan is a Professor in Fixed Prosthodontics at Sinai University. He is Director of both Prosthodontics division and Research unit as well as Coordinator of In-house Dental Lab. He is a Member of American Academy for Cosmetic Dentistry (AACD), International Congress of Oral Implantologists (ICOI) and International Association for Dental Research (IADR). He is the founder and director of “Train the Trainers” program. Dr.Rayyan is an author and co-author of 70 publications in national and international journals, as well as a member in Editorial Boards 3 Dental Journals. He also has 5 techniques in prosthodontics carrying his name.
Abstract: Purpose: To evaluate color stability and fracture resistance of CAD/CAM and manually fa... more Abstract: Purpose: To evaluate color stability and fracture resistance of CAD/CAM and manually fabricated tooth colored materials as crowns on primary molars. Methodology : Eighty epoxy replicas (Vertex- Dental B.V., The Netherlands) of minimally prepared primary molar were constructed to receive a tooth colored crown. Replicas were assigned into 4 groups (n=20) according to crown material used: CAD/CAM PMMA blocks (Telio Cad, Ivoclar Vivadent AG, Liechtenstein) [CC], self-polymerizing temporary resin material [SP] (Snap, Parkell, NY 11717 USA), auto-mix temporary resin material [AT] (Telio CS CB SP (∆E =5.4 ± 1.6), AM (∆E =6.7 ± 1.2) and TP (∆E =4.4 ± 2.5). On the other hand, CC crowns demonstrated high color stability (∆E=1.7 ± 0.2). CAD/CAM crowns demonstrated significantly higher fracture resistance (1417.9 ± 62 N) compared to manually fabricated crowns (SP=1096 ± 50, AM=989 ± 41 and TP=1297 ± 45). Conclusions: CAD/CAM PMMA crowns revealed superior fracture resistance and color ...
Journal of International Society of Preventive & Community Dentistry, 2021
Objective: Precision attachments may exert unfavorable stresses on abutments in distal extension ... more Objective: Precision attachments may exert unfavorable stresses on abutments in distal extension bases. This study compared between two reciprocation designs in attachment removable partial dentures (RPDs). Materials and Methods: Fourteen patients were allocated into two groups. Each patient received an attachment-retained RPD with one of the two types of attachments being studied. Group I received the integrated interlock type of reciprocation and group II received the parallel interlock type. Abutments were examined for modified plaque index, modified bleeding index, periodontal probing pocket depth, clinical attachment level, and modified papillary bleeding Index. Results: Comparisons of periodontal parameters between mesial and distal abutments within each group revealed no statistically significant difference. Means of these parameters were used for the comparisons. There was a significant difference at P < 0.05 in all parameters between the two groups at time of insertion a...
This study aimed to evaluate the clinical effect of crown margin position and crown material on t... more This study aimed to evaluate the clinical effect of crown margin position and crown material on the periodontal health. 200 patients were examined, half of the patients received all ceramic crowns and the rest received porcelain fused to metal crowns. Contra-lateral tooth of same patient served as control. Teeth restored with supragingival margins scored better bleeding index, plaque index and probing pocket depth index as compared to teeth restored with subgingival margins and there was no difference between all ceramic and porcelain fused to metal crowns on periodontal health.
Statement of problem: Removing cemented crowns is usually a complicated procedure that may lead t... more Statement of problem: Removing cemented crowns is usually a complicated procedure that may lead to irreversible damage to the tooth/crown and mostly necessitate remake of crown with added effort for both patient and clinician. Purpose: This in-vitro study evaluated an experimental two-component, screw-retained retrievable crown design in comparison to the conventional design. Materials and methods: A total of 120 extracted maxillary 2nd premolars received root canal treatment and were divided into two groups (n=60 each) according to the crown design they will receive. Gp CC received a threaded modified post, a composite core and a metal coping, while Gp RC received a two-component retrievable crown design. Fracture resistance was assessed by a 90 degrees vertical load to the center of the occlusal surface, using universal testing machine, under a constant crosshead speed of 0.5 mm/min until failure. Microleakage was assessed by placing specimens in methylene blue dye for 12 hours, s...
Purpose: To compare between the effect of chair-side and laboratory air particle abrasion (APA) o... more Purpose: To compare between the effect of chair-side and laboratory air particle abrasion (APA) on shear bond strength of different types of zirconia to composite resin. Materials and Methods: Study was divided into 2 groups (n=36): laboratory (L) and chairside (C) according to APA application methods. Each group was further divided into 3 subgroups according to type of zirconia used (High-Translucency (HT), Super-Translucency (ST), and TopTranslucency (TT)). Using CADCAM 8x8x3 zirconia cuboids were constructed, cleaned and sintered. Composite cuboids having dimensions of 6x6x3 were also constructed using custom made plexi-plates. Composite cuboids were cemented centrally to the zirconia cuboids with light cure under 5kg for 6 mins. After thermocycling for 1000 cycles, all specimens were dried and collected for testing. The shear bond strength of the specimens was measured utilizing universal testing machine at a crosshead speed of 0.5 mm/min. Failure load was recorded in Newton and...
Odontology / the Society of the Nippon Dental University, Jan 15, 2016
Obtaining ideal prosthetic framework design is at times hindered by anatomical limitations in the... more Obtaining ideal prosthetic framework design is at times hindered by anatomical limitations in the posterior region that might increase the risk for zirconia restoration fracture. Modification such as increasing the bulk thickness especially in the connector region could result in strengthening the zirconia framework. Three-unit zirconia fixed partial dentures replacing mandibular molars were fabricated using the following two techniques: CAD/CAM technology and manual copy milling. Modified framework with unveneered full thickness connectors were designed and fabricated with the aforementioned methods. Conventional frameworks (0.5 mm thick with rounded 3 mm connectors) served as control (N = 20). After cementation on epoxy dies, the frameworks were loaded to fracture in a universal testing machine. Fractured surfaces were prepared for examination using scanning electron microscopy. Statistical analysis revealed significant differences in fracture resistance between conventional and m...
Abstract: Purpose: To evaluate color stability and fracture resistance of CAD/CAM and manually fa... more Abstract: Purpose: To evaluate color stability and fracture resistance of CAD/CAM and manually fabricated tooth colored materials as crowns on primary molars. Methodology : Eighty epoxy replicas (Vertex- Dental B.V., The Netherlands) of minimally prepared primary molar were constructed to receive a tooth colored crown. Replicas were assigned into 4 groups (n=20) according to crown material used: CAD/CAM PMMA blocks (Telio Cad, Ivoclar Vivadent AG, Liechtenstein) [CC], self-polymerizing temporary resin material [SP] (Snap, Parkell, NY 11717 USA), auto-mix temporary resin material [AT] (Telio CS CB SP (∆E =5.4 ± 1.6), AM (∆E =6.7 ± 1.2) and TP (∆E =4.4 ± 2.5). On the other hand, CC crowns demonstrated high color stability (∆E=1.7 ± 0.2). CAD/CAM crowns demonstrated significantly higher fracture resistance (1417.9 ± 62 N) compared to manually fabricated crowns (SP=1096 ± 50, AM=989 ± 41 and TP=1297 ± 45). Conclusions: CAD/CAM PMMA crowns revealed superior fracture resistance and color ...
Journal of International Society of Preventive & Community Dentistry, 2021
Objective: Precision attachments may exert unfavorable stresses on abutments in distal extension ... more Objective: Precision attachments may exert unfavorable stresses on abutments in distal extension bases. This study compared between two reciprocation designs in attachment removable partial dentures (RPDs). Materials and Methods: Fourteen patients were allocated into two groups. Each patient received an attachment-retained RPD with one of the two types of attachments being studied. Group I received the integrated interlock type of reciprocation and group II received the parallel interlock type. Abutments were examined for modified plaque index, modified bleeding index, periodontal probing pocket depth, clinical attachment level, and modified papillary bleeding Index. Results: Comparisons of periodontal parameters between mesial and distal abutments within each group revealed no statistically significant difference. Means of these parameters were used for the comparisons. There was a significant difference at P < 0.05 in all parameters between the two groups at time of insertion a...
This study aimed to evaluate the clinical effect of crown margin position and crown material on t... more This study aimed to evaluate the clinical effect of crown margin position and crown material on the periodontal health. 200 patients were examined, half of the patients received all ceramic crowns and the rest received porcelain fused to metal crowns. Contra-lateral tooth of same patient served as control. Teeth restored with supragingival margins scored better bleeding index, plaque index and probing pocket depth index as compared to teeth restored with subgingival margins and there was no difference between all ceramic and porcelain fused to metal crowns on periodontal health.
Statement of problem: Removing cemented crowns is usually a complicated procedure that may lead t... more Statement of problem: Removing cemented crowns is usually a complicated procedure that may lead to irreversible damage to the tooth/crown and mostly necessitate remake of crown with added effort for both patient and clinician. Purpose: This in-vitro study evaluated an experimental two-component, screw-retained retrievable crown design in comparison to the conventional design. Materials and methods: A total of 120 extracted maxillary 2nd premolars received root canal treatment and were divided into two groups (n=60 each) according to the crown design they will receive. Gp CC received a threaded modified post, a composite core and a metal coping, while Gp RC received a two-component retrievable crown design. Fracture resistance was assessed by a 90 degrees vertical load to the center of the occlusal surface, using universal testing machine, under a constant crosshead speed of 0.5 mm/min until failure. Microleakage was assessed by placing specimens in methylene blue dye for 12 hours, s...
Purpose: To compare between the effect of chair-side and laboratory air particle abrasion (APA) o... more Purpose: To compare between the effect of chair-side and laboratory air particle abrasion (APA) on shear bond strength of different types of zirconia to composite resin. Materials and Methods: Study was divided into 2 groups (n=36): laboratory (L) and chairside (C) according to APA application methods. Each group was further divided into 3 subgroups according to type of zirconia used (High-Translucency (HT), Super-Translucency (ST), and TopTranslucency (TT)). Using CADCAM 8x8x3 zirconia cuboids were constructed, cleaned and sintered. Composite cuboids having dimensions of 6x6x3 were also constructed using custom made plexi-plates. Composite cuboids were cemented centrally to the zirconia cuboids with light cure under 5kg for 6 mins. After thermocycling for 1000 cycles, all specimens were dried and collected for testing. The shear bond strength of the specimens was measured utilizing universal testing machine at a crosshead speed of 0.5 mm/min. Failure load was recorded in Newton and...
Odontology / the Society of the Nippon Dental University, Jan 15, 2016
Obtaining ideal prosthetic framework design is at times hindered by anatomical limitations in the... more Obtaining ideal prosthetic framework design is at times hindered by anatomical limitations in the posterior region that might increase the risk for zirconia restoration fracture. Modification such as increasing the bulk thickness especially in the connector region could result in strengthening the zirconia framework. Three-unit zirconia fixed partial dentures replacing mandibular molars were fabricated using the following two techniques: CAD/CAM technology and manual copy milling. Modified framework with unveneered full thickness connectors were designed and fabricated with the aforementioned methods. Conventional frameworks (0.5 mm thick with rounded 3 mm connectors) served as control (N = 20). After cementation on epoxy dies, the frameworks were loaded to fracture in a universal testing machine. Fractured surfaces were prepared for examination using scanning electron microscopy. Statistical analysis revealed significant differences in fracture resistance between conventional and m...
Purpose: evaluate the bond strength of 2 fiber post systems to root canal dentine using 3 differe... more Purpose: evaluate the bond strength of 2 fiber post systems to root canal dentine using 3 different protocols of dual-cure resin cements.
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