Case by:
Gabriele Bavosi DDS, Pesaro, Italy
Andrea Tesei DDS, Pesaro, Italy
Tommaso Bologna DDS, Pesaro, Italy
Filippo Ban CDT, San Marino, Republic of San Marino
Alex Monticelli CDT, Pesaro, Italy

Lithium Disilicate Crown upon Zirconia Abutment.

A 50 years old nonsmoking female presented to our dental office for a routinely follow-up exam in November 2016 referring mild pian to 2.1 area.
Medical history was negative.
At physical examination VM 6mm and VD 4mm periodontal probing was observed. Pulp vitality test was negative.
Radiographic examination revealed external root resorption of 2.1 element some millimeters below the crestal bone.
Intra-oral examination revealed a fair oral hygiene.
Upon presentation of the various treatments, the patient refused veneers treatment plan and opted to extraction of the hopeless tooth and immediate restoration implant-supported. Clinically we observed enough bone to place an implant size 4.1 mm. Radiographically, enough bone heigh was available to receive up to 12mm implant to achieve the best primary stability.
Treatment plan consisted in post-extraction implant placement and immediate loading with a temporary resin crown upon temporary titanium abutment. Finalization at two months consisted in a lithium disilicate crown upon a zirconia abutment.
Maxillary and mandibular study models was obtained and a diagnostic wax up of the maxillary central incisor was performed.
Before surgery, the patient received a session of prophylaxis with oral hygiene instruction and 2g amoxicillin prophylactic regimen for endocarditis was administred.
Atraumatic extraction was made without forceps and after excluding acute purulent infection in the extraction site and implant placement was performed with good primary stability (Straumann Roxolid BLT, SLActive implant 4.1mm x 12mm).
To facilitate restorative procedures, to improve aesthetic and plaque control during oral hygiene a connective tissue augmentation procedure was performed harvesting in palatal region near maxillary tuberosity.
The procured graft from the palate was secured over the recipient site using an absorbable, synthetic, braided 6-0 sutures (Vicryl, Ethicon Inc, Johnson & Johnson International, Belgium) 1 mm coronal than adjacent elements in order to maintain a correct gingival contour after healing apical migration.
Porous deproteinized bovine bone scaffold (Bio-oss, Geistlich Pharma AG,Switzerland) then applied to completely fill the compartment among implant and post-extraction socket.
The temporary abutment was screwed to the implant and a provisional crown was fabricated using an A2 cold curing resin (Vertys Templus, Vertysystem, Vicenza).
The resin was added inter proximally to gently push the soft tissue and create a concavity on the ridge area until the optimum esthetic result of the emergence profile achieved but not buccally where autograft was secured in order to exclude every possibile load on it.
Finishing and polishing were completed using pumice polishing paste and the occlusal area was adjusted to made the provisional non functionally.
The implant screw access canal was sealed using a provisional composite material (Vertise Flow, Kerr, USA).
A transparent mouth-guard was fabricated and administered to improving the impact absorption ability, patient had to wear the mouth-guard all over the day except for meals.
Two months later, the provisional restoration was removed and the implant was examined to control soft tissue healing that was completed and stable with an optimal gingival contour.
For the final impression, the mail goal was to transfer the created emergence profile to permanent restoration accurately.
The temporary abutment with provisional restoration was removed. A silicon putty impression material was mixed and placed in a plastic cup. While the putty material was still soft, the temporary abutment with the restoration fitted on an implant replica (Straumann, Switzerland) and placed directly in the soft mix. The implant replica and the gingival third of the crown were immersed in the putty material. After complete setting of the putting material, the temporary abutment with the restoration was removed and impression coping was screwed to the implant replica. An acrylic resin material powder and liquid (Pattern Resin LS, GC America Inc, Alsip) was mixed and placed around the impression coping in order to fill the area of gingival contour. After complete setting, the impression coping was transferred to patient mouth and fitted accurately. Final impression was taken using polyether impression material (Impregum, 3M Espe, Seefeld, Germany).
The impression was sent to laboratory with the prescription for a full-coverage IPS e.emax press lithium disilicate crown (Ivoclar Vivadent, Schaan, Liechtenstein)and a zirconia covered Variobase abutment (Straumann, Switzerland).
Zirconia covered Variobase abutment was design and milled using a computer-aided manufacturing (CAM) technique.
Lithium disilicate crown was pressed from A1 IPS empress MT ingots (Ivoclar Vivadent, Schaan, Liechtenstein) using a Programat EP 5010 (ivoclar Vivadent, Schaan, Liechtenstein) and stratified to obtain the best aesthetic result.
After ensured the optimal fitting, the abutment was screw-retained using a screw torque of 25 Ncm in accordance with manufacturer’s recommendation.
An advanced try-in at biscuit bake was made to ensure color match, aesthetic appearance, marginal contacts integrity and occlusion.
Abutment was sterilized using a alcohol-free disinfectant (Isorapid, Oro Clean Chemie AG,Switzerland)
To achieve the best adhesion from lithium disilicate crown and zirconia abutment, the in internal areas of crown were etched with 5% hydrofluoridric acid for 20 seconds and rinsed. A primer (Ceramic Primer Plus, Kuraray Noritake dental Inc. Japan) was applied on the same surface and dried.
Then zirconia abutment was blasted with 90 µm alumina powder and a primer Ceramic Primer Plus, Kuraray Noritake dental Inc. Japan) applied on his surface and dried.
The restoration was then cemented using an adhesive resin cement system(Panavia V5, Kuraray Noritake dental Inc. Japan).

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