Arthur Nimmo

Preservation of existing soft-tissue contours in the transition from a tooth to an implant restoration in the esthetic zone using a flapless approach: a clinical report.

Two-stage placement of a dental implant is a well-established method for restoring a missing anterior tooth; however, replacement of an anterior tooth by using two-stage implant surgery may result in changes in the interdental papilla height and loss of alveolar bone with compromised esthetic results. Alternatively, the use of a one-stage minimally invasive surgical technique followed by immediate provisionalization may facilitate achievement of esthetic and functional success with minimal discomfort and clinical time. This article presents a clinical case with a single anterior tooth replacement, illustrating ridge preservation with healing, delayed implant placement with immediate provisionalization of the implant to support the soft tissue, and a method of recording the soft-tissue contour in the final impression to achieve an optimal esthetic result.

A comparative study of the accuracy between plastic and metal impression transfer copings for implant restorations

PURPOSE A precise transfer of the position and orientation of the antirotational mechanism of an implant to the working cast is particularly important to achieve optimal fit of the final restoration. This study evaluated and compared the accuracy of metal and plastic impression copings for use in a full-arch mandibular edentulous simulation with four implants. MATERIALS AND METHODS Metal and plastic impression transfer copings for two implant systems, Nobel Biocare™ Replace and Straumann SynOcta®, were assessed on a laboratory model to simulate clinical practice. The accuracy of producing stone casts using these plastic and metal impression transfer copings was measured against a standard prosthetic framework consisting of a cast gold bar. A total of 20 casts from the four combinations were obtained. The fit of the framework on the cast was tested by a noncontact surface profilometer, the Proscan 3D 2000 A, using the one-screw test. The effects of implant/system and impression/coping material on gap measurements were analyzed using repeated measures ANOVA. RESULTS The findings of this in vitro study were as follows: plastic copings demonstrated significantly larger average gaps than metal for Straumann (p = 0.001). Plastic and metal copings were not significantly different for Nobel (p = 0.302). Nobel had significantly larger average gaps than Straumann for metal copings (p = 0.003). Nobel had marginally smaller average gaps than Straumann (p = 0.096) for plastic copings. The system-by-screw location interaction was significant as well (p < 0.001), indicating significant differences among the four screw locations, but the location differences were not the same for the two systems. A rank transformation of the data was necessary due to the nonnormal distribution of the gap measurements. No adjustments were made for multiple comparisons. CONCLUSIONS The metal impression copings were more accurate than plastic copings when using the Straumann system, and there was no difference between metal and plastic copings for the Nobel Replace system. The system-by-screw location was not conclusive, showing no correlation within each system.

Integrating conventional and CAD/CAM digital techniques for establishing canine protected articulation: A clinical report

Canine protected articulation is widely accepted for patients requiring extensive oral rehabilitation. Computer-aided design and computer-aided manufacturing (CAD/CAM) restorations have been primarily designed in occlusion at the maximum intercuspal position. Designing a virtual articulator that is capable of accepting excursive occlusal records and duplicating the mandibular movements is a challenge for CAD/CAM technology. Modifying tooth shape using composite resin trial restorations to produce esthetic results and later scanning the modified teeth to create milled crowns is becoming a popular use of the CAD/CAM technology. This report describes a technique that combines conventional and CAD/CAM prosthodontic techniques for milling crowns for canine teeth that are designed to establish or improve canine protected articulation. This technique involves designing and fabricating interim restorations based on diagnostic waxing, scanning the designs intraorally, and storing them in software as pretreatment digital records. The scanned designs are then applied to the digital representation of the prepared teeth to fabricate the definitive restorations.

Stabilized Record Base for Implant Treatment

It is important to obtain an accurate interocclusal record for the restoration of patients undergoing implant treatment. Atrophic alveolar bone in the mandible not only limits the placement of implants, but also contributes to deficient ridge morphology resulting in unstable record bases. Securing the record base to the implants is a useful way to obtain an accurate registration. The technique presented in this article uses two widely spaced implants as the optimal number of implants to stabilize record bases.

Metal denture inserts in the treatment of elongated maxillary tuberosities

L ack of space between the elongated maxillary tuberosity and the retromolar pad can cause technical problems for the dentist. The maxillary denture should cover the maxillary tuberosity, a primary stress bearing area, and should extend into the hamular notch. The mandibular denture should cover the retromolar pad to provide a good border seal. The denture base should be 2 mm thick for adequate strength. A minimum of 5 to 6 mm is necessary between the tuberosity and the retromolar pad to accommodate the denture base and movement. The preferred treatment for these patients is surgery to reduce the size of the tuberosity by removing bone or soft tissue or both and thus create more space.’ However, surgery may be contraindicated because of anatomic, medical, or psychologic reasons. For these patients, the use of metal inserts can provide an alternative method of conservative treatment. The inserts provide coverage of the maxillary tuberosities and the retromolar pads and permit free movement of the mandible without interference from the denture bases. This article outlines the technical procedures for using metal denture inserts in the treatment of elongated maxillary tuberosities.

Managing Gag Reflex during Removable Partial Denture Treatment: A Review and a Clinical Report: Managing Gag Reflex during RPD Treatment

A gag reflex is a common occurrence during dental procedures. A hypersensitive gag reflex is less frequently encountered and may prevent the dental provider from successfully completing critical clinical stages, resulting in poor treatment outcomes. Once patients suffer an unpleasant gag reflex experience in a dental office, they may become phobic, delaying or postponing their dental treatment. The purpose of this article is to review available treatment options and present a report of a partially edentulous patient with an exaggerated gag reflex, focusing on clinical management using a simple yet effective table salt technique and proper prosthesis design.

Impression Making and Lab Work Authorization Forms in Fixed Prosthodontics: A Preclinical Exercise

Introduction Making a final impression using a custom tray for fixed prosthodontics is a widely accepted procedure that is taught in many dental schools. As such, achieving competency in impression making and lab communication is a new Commission on Dental Accreditation curriculum requirement for all dental schools in the US. Methods This resource presents an instructional slide show on the clinical steps required in fabricating a custom tray using a visible light-cured resin, making a successful impression, and writing a work authorization form for the fabrication of a fixed dental prosthesis. The presentation also contains a brief overview of alternative techniques and materials used as well as basic points for self-evaluation for the custom tray and the final impression. This activity was conducted as a small-group team-based learning exercise in a preclinical setting, where a self-assessment form was provided for students to evaluate their work. Results Examiners indicated that students who completed this exercise had a deeper understanding of the sequencing of steps involved in the construction of a fixed partial denture as well as better lab communication skills compared to students from previous classes who did not participate in the exercise. Discussion The preclinical setting provided students with a relaxed atmosphere for fabricating a custom tray using visible light-curing material. This exercise is part of a larger preclinical exercise that takes students through all the steps involved in the fabrication of a fixed dental prosthesis, from impression making to the evaluation of the framework made by the lab.

A Single Visit Direct Technique to Provisionally Restore Occlusion for a Full-Mouth Rehabilitation: A Clinical Report.

Attrition of the dentition can negatively affect esthetics and function. When reconstructing patients with attrition who require restoration at increased occlusal vertical dimension (OVD), it is necessary to first evaluate the OVD using a removable interim prosthesis to ensure that the patient will tolerate the new position. The transition to fixed interim prostheses has to be carefully planned to achieve the desired OVD. One approach is to prepare all teeth in a single day and place full-arch interim prostheses; however, this can be tiring for the patient and prosthodontist. An alternative approach is to prepare one arch and place interim prostheses, while using composite resin in the opposing arch to maintain the newly established OVD. A diagnostic wax-up at the proposed OVD is completed and duplicated in stone. A vacuform matrix is loaded with composite resin and applied to the unprepared etched teeth of the opposing arch to restore form and occlusion until full contour interim prostheses are placed at a later visit.

A conservative approach to rebasing an implant-retained fixed complete denture

After years of service, the acrylic resin base of an implant-retained fixed complete dental prosthesis may need to be replaced because of the wear of the acrylic resin teeth. The most common methods used by dental laboratories to remove the acrylic resin from the metal framework are either burning with a flame or grinding. Both of these methods risk exposing the dental laboratory technician to hazardous by-products and damaging or contaminating the metal framework or the gold cylinders. This article presents a safe approach to removing acrylic resin while preserving the integrity of the framework. The technique involves heating the prosthesis to beyond the glass transitional temperature of the acrylic resin to allow the resin to be safely peeled off the framework.

Using a posterior provisional crown as a matrix for an amalgam foundation.

Echeto and Nimmo Echeto and Nimmo When a crown is planned for a posterior tooth, there may be insufficient remaining tooth structure. In this situation, the integrity of the tooth has been compromised and it may be difficult to stabilize the matrix for amalgam foundation placement. Using a provisional crown as a matrix for the amalgam foundation is one approach to this dilemma. The tooth is prepared and a provisional crown is fabricated and modified to serve as a matrix for the amalgam foundation placement. This article describes a technique to make an amalgam foundation in a posterior tooth with minimal remaining tooth structure and the use of bonding material in vital teeth. A well placed core restoration is essential for tissue health, patient comfort, and a successful definitive restoration. The structural integrity of posterior teeth is frequently compromised due to extensive restorations with failing margins, fracture, and/or extensive recurrent caries. Clinically and radiographically, it may be difficult to assess whether the amount of tooth structure remaining is adequate for the fabrication of a fixed restoration (Fig. 1). The process of crown preparation aids in determining the restorability of a tooth and the need for adjunctive procedures. If endodontic therapy is indicated, the restorability of the tooth must be determined prior to treatment.1 After preparation, the wall thickness should be at least 1 mm and the crown margins should be positioned with a minimum of 1.5 mm of Using a posterior provisional crown as a matrix for an amalgam foundation