Periklis Proussaefs

The use of resorbable collagen membrane in conjunction with autogenous bone graft and inorganic bovine mineral for buccal/labial alveolar ridge augmentation: A pilot study ☆

STATEMENT OF PROBLEMnNo study provides human histologic evidence regarding the use of resorbable collagen membrane for a 2-stage localized alveolar augmentation procedure.nnnPURPOSEnThe purpose of this pilot study was to evaluate the potential of use of a resorbable collagen membrane in conjunction with an autogenous bone graft and inorganic bovine mineral (IBM) for labial/buccal alveolar ridge augmentation prior to placing dental implants. Material and methods Seven consecutively treated human patients participated in the study. All patients received labial/buccal alveolar ridge augmentation. An autogenous block graft was secured at the recipient site with fixation screws and a mixture of autogenous particulate with IBM was placed at the periphery. Resorbable collagen membrane was used as a barrier. Radiographic and laboratory measurements were made to quantify ridge augmentation and resorption rate. Preoperative and postoperative stone casts were used to quantify alveolar ridge augmentation. Volumetric evaluation was measured in mL whereas linear laboratory evaluation was measured in millimeters. Measurements were made 1 and 6 months after bone grafting. Histologic and histomorphometric analysis from the grafted area evaluated new bone formation, and osteoconductivity of IBM.nnnRESULTSnFor all patients Type II to III bone quality was achieved at the augmented sites. The implant survival rate was 100% at second-stage surgery. No complication was observed at the recipient sites. Radiographic evaluation revealed 4.65 mm labial/lingual augmentation, whereas laboratory analysis revealed 4.57 mm. Volumetric laboratory analysis demonstrated 1.00 (+/- 0.29) mL alveolar ridge augmentation 6 months after bone grafting and 13.79% resorption between months 1 and 6. Histomorphometric analysis revealed that on average, the area occupied by bone was 34.28% (range 24 to 50; +/-9.05),] soft tissue 46.00% (+/-9.20%; range 30% to 55%), and IBM particles 19.71% (+/-11.74%, range 3% to 42%). The proportion of the surface of the IBM particles in contact with bone was 47.14% (range 15% to 64%; SD 17.21%).nnnCONCLUSIONSnResorbable collagen membranes may be used as barriers for labial/buccal alveolar ridge augmentation procedures.

Crowns Cemented on Crown Preparations Lacking Geometric Resistance Form. Part II: Effect of Cement

PURPOSEnThis study evaluated the effect of different cements on resistance to dislodgment of crowns cemented on preparations lacking geometric resistance form.nnnMATERIALS AND METHODSnA preparation that offered no geometric resistance form, with 20 degrees total occlusal convergence (TOC), 0.9 mm wide shoulder finish line, and a 2.5 mm axial wall height was created on an ivorine tooth using a milling machine. Ten metal test specimen die replicas and 10 standardized metal crowns with recipient sites for the application of external forces through a universal testing machine were fabricated. The crowns were cemented on the dies under 5 and 10 kg external loads, the marginal openings measured, loaded to dislodgment, and cleaned of cement. The process was repeated using zinc oxide and eugenol (ZOE), zinc phosphate (ZPh), resin modified glass ionomer (RMGI), and composite resin (CR) cements.nnnRESULTSnMarginal openings under 5 kg cementation loads were 74.63 (+/-15.04) for ZOE, 75.98 (+/-18.20) microm for ZPh, 98.58 (+/-22.62) microm for RMGI, and 105.82 (+/-20.07) microm for CR cements respectively; under 10 kg cementation loads they were 57.62 (+/-15.86) microm, 59.55 (+/-15.41) microm, 95.00 (+/-19.52) microm, 101.30 (+/-12.52) microm respectively. Oblique dislodgment forces, measured with a Universal testing machine, were 40.18 (+/- 6.76) N for ZOE, 215.65 (+/-45.79) N for ZPh, 165.43 (+/-19.53) N for RMGI, and 181.54 (+/-30.75) N for CR respectively when crowns were cemented under 5 kg loads. The corresponding values for 10 kg loads were 38.62 (+/-4.19), 274.86 (+/-54.22), 139.70 (+/-21.71), and 160.40 (+/-21.21) respectively. Only zinc phosphate cement produced statistically enhanced resistance when crowns were cemented under 10 kg force (p value = 0.035).nnnCONCLUSIONSnUnder the conditions of the present study only crowns cemented with zinc phosphate displayed increased resistance to dislodgment on preparations lacking resistance form.

Immediate provisionalization with a CAD/CAM interim abutment and crown: A guided soft tissue healing technique

A technique is described in which a single interim abutment and crown were fabricated in advance and placed the day of dental implant surgery. The contours of the interim crown were identical to the contours of a tentatively designed definitive prosthesis and allowed the tissue to heal and obtain contours that accommodated the contours of the definitive prosthesis. After osseointegration wasxa0established, a definitive impression was made with a custom computer-assisted design and computer-assisted manufacturing impression coping. The definitive prosthesis then was fabricated.

CAD-CAM implant-supported fixed complete dental prosthesis with titanium milled molars: A clinical report

Implant-supported fixed complete dental prostheses have been associated with a high implant success rate in long-term studies. However, they have also been associated with a high frequency of prosthetic complications. The most frequent and primary prosthetic complication has been the fracture or wear of the occlusal surface of acrylic resin teeth that are typically attached to a metal framework. The design of the framework in this clinical report involved the incorporation of metal occlusal surfaces for the posterior first molars to the framework. The titanium framework was fabricated with computer-aided design and computer-aided manufacturing (CAD-CAM) technology.xa0The remaining teeth were restored in a conventional manner with acrylic resin denture teeth bonded to the titanium framework. This was expected to maintain the occlusal vertical dimension and also reduce the frequency of the primary complications associated with these prostheses.

Combining guided alveolar ridge reduction and guided implant placement for all-on-4 surgery: A clinical report

Immediate restoration with the all-on-4 concept has become an established treatment option. The technique involves alveoloplasty before implant placement to provide space for the prosthetic components and to provide a platform on which dental implants can be placed in clinical situations where a knife-edge alveolar ridge is present. Guided implant surgery involves the fabrication of a guide by using data from cone-beam computed tomography (CBCT) and implant surgery performed without flap reflection. In the presented technique, a printed cast based on a CBCT is used to fabricate a guide for both alveolar ridge reduction and guided implant surgery. The alveolar ridge reduction and implant surgery are virtually simulated in the laboratory to provide space for the restorative components and to avoid critical anatomic landmarks (mental nerve or perforation of the lingual mandibular plate). The described surgical guide enables guided alveolar ridge reduction and guided implant placement where the implant placement performed in the laboratory can be duplicated clinically during implant surgery.

A technique for immediately restoring single dental implants with a CAD-CAM implant-supported crown milled from a poly(methyl methacrylate) block

This technique is used when a single dental implant is placed. A stent made of autopolymerized acrylic resin was used to transfer the implant position to the laboratory. Once the implant position was transferred, the stone cast was scanned, and a computer-aided design and computer-aided manufacturing (CAD-CAM) interim implant-supported crown was milled from a poly(methyl methacrylate) (PMMA) block. A titanium insert, in contact with the implant platform and not the PMMA material, was used to support the crown. The interim prosthesis was then placed intraorally. The soft tissues were sutured, and the interim prosthesis was left for a period of at least 3 months to confirm osseointegration and allow the soft tissue to heal. A CAD-CAM titanium impression coping was made and used for the definitive impression. The contours of the impression coping were identical to the contours of the interim restoration. The data of the digital design of the interim prosthesis were saved, and the definitive prosthesis was fabricated with contours identical to those of the interim prosthesis.

Use of a CAD-CAM poly(methyl methacrylate) interim prosthesis for direct intraoral splinting

This article describes a technique where an interim computer-aided design and computer-aided manufacturing (CAD-CAM) prosthesis is milled from a poly(methyl methacrylate) blank to confirm esthetics, occlusion, function, phonetics, and accessibility for oral hygiene. The interim prosthesis is then sectioned and reconnected intraorally with autopolymerizing acrylic resin. This interim prosthesis is used to fabricate the definitive stone cast. The interim prosthesis is then scanned with a laboratory scanner. By applying this technique, the implant positioning can be related to the occlusal plane, the contours of the teeth, and the flange. The clinician can more effectively design the definitive prosthesis because the location of the implants and the exact contours of the teeth are all captured in a single digital file.

The combination prosthesis: A digitally designed retrievable cement- and screw-retained implant-supported prosthesis

The technique described offers a digital workflow for designing and fabricating a combination cement- and screw-retained implant-supported prosthesis. After making the definitive impression and definitive stone cast, the definitive combination prosthesis is digitally designed. Custom-milled titanium abutments and cementable superstructure prosthesis are designed and milled by having occlusal access channels of the prosthesis correspond to the occlusal access channels of the custom abutments. After intraorally confirming the esthetics, occlusion, and fit, the prosthesis is cemented intraorally and removed as a screw-retained prosthesis. After excess cement is removed, the combination prosthesis is placed intraorally, and composite resin is used to seal the occlusal access channels.

Custom CAD-CAM healing abutment and impression coping milled from a poly(methyl methacrylate) block and bonded to a titanium insert

This article describes a technique in which a custom-made computer-aided design and computer-aided manufacturing (CAD-CAM) healing abutment milled from a poly(methyl methacrylate) (PMMA) block is fabricated and bonded to a titanium metal insert. An impression is made during dental implant surgery, and the CAD-CAM custom-made healing abutment is fabricated before second-stage surgery while appropriate healing time is allowed for the dental implant to osseointegrate. The contours of the healing abutment are based on the contours of a tentatively designed definitive prosthesis. The healing tissue obtains contours that will be compatible with the contours of the definitive prosthesis. After the milling process is complete, a titanium metal insert is bonded to the healing abutment. Placement of the custom-made CAD-CAM healing abutment at second-stage surgery allows the tissue to obtain contours similar to those of the definitive prosthesis. A custom-made CAD-CAM impression coping milled from a PMMA block and with a titanium insert is used for the definitive impression after the soft tissue has healed. This technique allows guided soft tissue healing by using a custom-made CAD-CAM healing abutment and impression coping.