SIMPLIFIED TECHNIQUE FOR REMOVAL OF PREFABRICATED THREADED POSTS

This paper describes a time-saving procedure for the removal of prefabricated threaded posts. In this technique, a slit is prepared in the head of the post to-be-removed so that it can be engaged by a jewelers’ precision stainless steel flat-blade screwdriver which would drive it out when rotated counterclockwise. This simple technique spares the clinician valuable time and effort during removal, requires minimal or no loss of valuable tooth structure compared to other techniques. It is also conservative in the sense that it does not expose dental tissue to thermal insults from use of ultrasound

“Orange-Peeling” An innovative fixed tooth preparation technique

This report describes an innovative technique of crown preparation, called “Orange-Peeling”, a straight forward technique valuable for increasing accuracy and speed of the procedure. The concept of this new technique evolves about undermining surface enamel by cutting through it from the side rather than grinding throughout the entire hard surface enamel

LOS FALSOS AMIGOS EN LA FRASEOLOGÍA ESPAÑOL–ÁRABE: EL CASO DE LOS FRASEOLOGISMOS SOMÁTICOS

The aim of this paper is to stimulate the attention of contrastive phraseology between Arabic and Spanish languages. In this work will be studied the contrastive analysis of false friends in the somatic phraseology between Spanish and Arabic languages. On the other hand, this paper finds out, by examples, the serious problem of false friends, which set out in the translatological and linguistic field.Este artículo tiene como objetivo estimular el interés de la investigación fraseológica contrastiva entre el árabe – español. Se investiga el análisis contrastivo de los falsos amigos en la fraseología somática español - árabe.Por otro lado, éste trabajo averigua, a través de los ejemplos, el serio problema que plantean los falsos amigos en el campo traductológico y lingüístico

Comparison between different surface treatment methods on shear bond strength of zirconia (in vitro study)

To compare the effect of Er:YAG Laser and Air particle abrasion (APA) surface treatments on shear bond strength of Y-TZP to composite resin cuboids in the presence and absence of primer application and salivary contamination. Seventy-two cuboidal shaped specimens 7x7x3 were prepared from Y-TZP using CADCAM, cleaned and sintered. Specimens were divided into 2 main groups (n=36) according to surface treatment method; Air particle abrasion (A) and laser (L). Each group was subdivided into 2 subgroups (N = 18) according to surface modification using primer; each subgroup was further divided into 2 subdivisions (N=9) according to the presence of salivary contamination; APC (Air particle abrasion, primer, contamination), AP (Air particle abrasion, primer), AC (Air particle abrasion, contamination), A (Air particle abrasion), LPC (Laser, primer, contamination), LP (Laser, primer), LC (Laser, contamination), L (Laser). Composite cuboids having dimensions of 6x6x3 were also fabricated using custom made plexi plates. Composite cuboids were cemented centrally to zirconia cuboids and light cured under 5 kg weight for 6 mins. Shear bond strength of specimens was measured utilizing universal testing machine at a crosshead speed of 0.5 mm/min. Failure loads were recorded in Newton. SBS was calculated according to equation: SBS (MPa) = load (N)/area(mm2). Viewing shear bond strength between studied groups, group APNC (484.02±85.02) showed higher mean value compared to ANPNC (122.09±55.80), also LNPNC (120.87±65.10) showed higher mean value in comparison to LPNC (170.78±53.22). APNC (484.02±85.02) and APC (592.22±189.65) showed higher mean values than LPNC (170.78±53.22) and LPC (3227.66±108.28) in sequence. APA showed higher SBS values than Er:YAG surface treatment. Primer showed better results than no primer coating. Artificial saliva contamination did not affect the SBS of zirconia compared with no contamination results

Fracture Resistance of computer aided endo-crowns versus conventional endo-supported computer aided full crowns

The purpose of the present study was to investigate the fracture resistance of computer aided endo-crowns versus conventional core-supported computer aided full crowns. Ninety human teeth were collected, 30 for each type (maxillary central incisors, maxillary 1st premolars and maxillary 1st molars). Specimens were divided into 3 groups (n=10) according to restoration used: 1) PC: Post-core and crown; 2) NC: Nayyar core and crown and 3) EC: Endo-crown. Each group was further subdivided into 3 subgroups according to the tooth used: I (Incisor), P (Premolar) and M (Molar). For group PC: Fiber post (Radix, Dentsply Maillefer) were cemented using resin cement (Calibra Dual Cure, Denstply Detrey GmbH). For group NC: 3 mm of gutta percha of every canal was removed. For groups PC and NC, after etching and bonding of root-face, transparent core former (Coltène/ Whaledent) was filled with SDR (Smart Dentine Replacement, Dentsply Detrey GmbH) and inverted onto root-face and cured. All specimens were individually scanned and thermocycled for 1000 cycles then submitted to compression test using universal testing machine (Instron 8874; Instron Corp.) Fracture was confirmed by sudden drop in load readings. Subgroup IPC scored the highest mean among group I and subgroup PNC scored the highest mean among group P. One-Way ANOVA detected significant differences among groups I and M with p\u3c 0.05 in I and M groups. Regarding P group, P-value was \u3e 0.05 indicating no significant differences among group. Endocrown showed the highest fracture resistance means in molars, while Nayyar core and crown showed the highest fracture resistance means in premolars. However, post-core and crown revealed the highest fracture resistance means in incisors

EFFECT OF LIGHT TRANSMITTING ABILITY OF FIBER POST ON BOND STRENGTH OF SELFADHESIVE RESIN CEMENT TO RADICULAR DENTINE

Aim: to investigate the effect of different light transmitting ability of two fiber posts systems on bond strength to the root canal dentine using dual cure self-adhesive resin cement. Materials and methods: 24 freshly extracted human premolars were decoronated and endodontically treated. Post spaces were prepared to a depth of 8 mm and width of 1.3 mm using manufacture’s supplied drills. Teeth were randomly classified into two main groups (n= 12) according to fiber post light transmission ability; group I; non-light transmitting fiber posts (NLT) (Reforpost, Angelus), group II; light transmitting fiber post (LT) (Exacto, Angelus). Both groups were cemented using self-adhesive resin cement (SpeedCEM, Ivoclar Vivadent). Using low speed saw (IsoMet, Buehler), a 2 mm thickness coronal, middle and apical sections were obtained from each sample. Then they were subjected to push out test using Instron machine (Lloyd Instruments Ltd) until failure. Data was collected and statistically analyzed. Results: the highest means in the coronal and middle parts was found, when using light transmitting fiber post, which scored (11.75, 10.30 MPa) compared with (6.51, 6.98 MPa) when using non-light transmitting group. One-way ANOVA among the groups revealed a significant difference between non-light and light transmitting fiber post. However, there is no significant difference on the middle and the coronal parts. Conclusions: There was no significant difference between non-light and light transmitting fiber post when all sections were added together. There is a reasonable doubt regarding the ability of light to reach more than 4 mm depth

A COMPARISON BETWEEN THE EFFECT OF DIFFERENT PRESSURES OF AIR PARTICLE ABRASION BEFORE AND AFTER SINTERING WITH AND WITHOUT ZIRCONIA LINER ON BOND STRENGTH OF RESIN TO ZIRCONIA SURFACE

This study aimed to compare the effect of different pressures of air particle abrasion 2 and 4 bars before and after sintering with and without zirconia liner on SBS of resin to zirconia Surface. Materials and Methods: 54 zirconia cuboids 8×8×3 mm were milled and divided into 6 equal groups (N=9) according to surface treatment; sintered with ceramic liner application and 2 bars pressure (SL2) and with 4 bars pressure (SL4), sintered with no ceramic liner and 2 bars pressure (SN2) and 4 bars pressure (SN4), unsintered with no ceramic liner and 2 bars pressure (UN2) and 4 bars pressure (UN4). Specimens underwent thermocycling (1000 cycles) between 5 ̊ and 55 ̊ Celsius with dwell time of 10 seconds, and submitted to SBS test. Data was statistically analysed. Results: All 4 bars APA groups showed higher SBS than 2 bars groups with significant difference between SL4 group (4.7±2.07) and SL2 group (2.58±1.94). Groups with APA before sintering (12.42±2.56) showed significantly higher SBS than APA after sintering (6.35±3.7). SL2 group showed least SBS with significant difference (2.58±1.94) compared to UN2 (11.83±3.35) and SN2 (7.87±2.12). SL4 group (4.7±2.07) showed the least SBS compared to the UN4 (13±1.38), and SN4 (10.24±2.94) groups. Conclusion: It was found that APA of zirconia surface before sintering yielded superior performance than APA after sintering, also 4 bars APA pressure application showed higher SBS than 2 bars pressure, application and firing of ceramic liner onto zirconia surface didn’t enhance SBS

EFFECT OF LIGHT TRANSMITTING ABILITY OF FIBER POST ON BOND STRENGTH OF SELFADHESIVE RESIN CEMENT TO RADICULAR DENTINE

Aim: to investigate the effect of different light transmitting ability of two fiber posts systems on bond strength to the root canal dentine using dual cure self-adhesive resin cement. Materials and methods: 24 freshly extracted human premolars were decoronated and endodontically treated. Post spaces were prepared to a depth of 8 mm and width of 1.3 mm using manufacture’s supplied drills. Teeth were randomly classified into two main groups (n= 12) according to fiber post light transmission ability; group I; non-light transmitting fiber posts (NLT) (Reforpost, Angelus), group II; light transmitting fiber post (LT) (Exacto, Angelus). Both groups were cemented using self-adhesive resin cement (SpeedCEM, Ivoclar Vivadent). Using low speed saw (IsoMet, Buehler), a 2 mm thickness coronal, middle and apical sections were obtained from each sample. Then they were subjected to push out test using Instron machine (Lloyd Instruments Ltd) until failure. Data was collected and statistically analyzed. Results: the highest means in the coronal and middle parts was found, when using light transmitting fiber post, which scored (11.75, 10.30 MPa) compared with (6.51, 6.98 MPa) when using non-light transmitting group. One-way ANOVA among the groups revealed a significant difference between non-light and light transmitting fiber post. However, there is no significant difference on the middle and the coronal parts. Conclusions: There was no significant difference between non-light and light transmitting fiber post when all sections were added together. There is a reasonable doubt regarding the ability of light to reach more than 4 mm depth

Influence of core color on final shade reproduction of zirconia crown in single central incisor situation ? An in vivo study

A lot of shaded zirconia blocks are being introduced into the market. Their effect on the final shade of the restoration is yet uncertain. Twenty-four zirconia crowns were fabricated for 8 patients who needed to restore a single maxillary central incisor, and divided into 3 groups according to the color and type of the zirconia (Zr) used (white Zr core, colored Zr core, and monolithic high translucency (ht) Zr crowns). Using Easyshade spectrophotometer, delta E color difference was calculated between fabricated crown and adjacent tooth. The ?Es obtained were assessed based on 1.6 ?E which represented the color difference that could not be detected by the human eye and considered clinically acceptable. No statistically significant values were found between the 3 groups related to different Zr color and type. Within the limitations of this study, it could be concluded that the shade of the zirconia blank had no significant effect on the final color of the crown. This raises reasonable doubt about the necessity to use colored zirconia blanks or use of dip-in solutions. The clinical implications were that, there was no need to use colored zirconia cores to get more esthetically pleasing restorations with respect to color perception. The use of monolithic high translucent zirconia crowns gained the advantages of high translucency and color reproduction

Influence of resin cement shade on the color and translucency of zirconia crowns

Zirconia crowns are highly attractive for clinicians, although have poor translucency when used as single restorations, in addition to unknown effect of resin cement shade on final cemented crown shade. This study aimed to assess effect of resin cement opacity on color replication potential of different zirconia frameworks with target tooth color, in addition to different zirconia crowns translucency evaluation. Twenty-four zirconia crown restorations were fabricated to restore single central maxillary incisor for 8 patients, divided into 3 groups according to color and type of zirconia used (white Zr core, colored Zr core and monolithic HT Zrcowns). Each group was further subdivided into 2 subgroups according to resin cement shade. Using Easyshade spectrophotometer, Delta E color difference was calculated between each crown parameters using 2 different resin luting cement shades and adjacent target tooth. Translucency parameters (TP) were tested for finished crowns. ?Es obtained were assessed based on ?Eof 1.6 which represented color difference that could not be detected by human eye and considered clinically acceptable. No statistically significant values were found between subgroups related to different resin cement shade. Translucency parameters showed statistically significant different values. Monolithic crowns showed highest translucency parameters followed by Zr crowns on white cores then Zr crowns on colored cores. Resin cement shade didn?t affect final color perception. Monolithic high translucency crowns usage gained advantages of high translucency and delamination prevention. Zirconia crowns could be cemented by opaque or transparent cement without affecting final color