John R. Agar

Cement removal from restorations luted to titanium abutments with simulated subgingival margins

STATEMENT OF PROBLEM The process of removing excess cement from subgingival margins after cementation of restorations to implant abutments may lead to scratching of the abutments or incomplete cement removal. PURPOSE The purpose of this study was to investigate and to compare the surfaces of abutments after the removal of three cements (glass ionomer, resin, and zinc phosphate) by use of three instruments (gold coated scaler, rigid plastic scaler, and stainless steel explorer). MATERIAL AND METHODS Six investigators removed zinc phosphate, glass ionomer, and resin cements with explorers, gold coated scalers, and rigid plastic scalers with a model simulating clinical conditions. The surface of Brånemark abutments with cemented restorations were examined with a microscope at 20x for scratches and cement remnants. RESULTS Statistical analysis of the results were inconclusive about which combination of instrument and cement worked most effectively. CONCLUSION A surprising amount of cement remnants and scratching of abutments was observed. Although the six investigators were experienced in prosthodontic and implant procedures, there was variation in the results of their cement removal.

Computer-aided technology for fabricating complete dentures: systematic review of historical background, current status, and future perspectives.

STATEMENT OF PROBLEM Computer-aided technology is an emerging method for fabricating complete dentures. Consolidated information about historical background, current status, and scope for the future is lacking. PURPOSE The purpose of this systematic review was to analyze the existing literature on computer-aided technology for fabricating complete dentures and provide the reader with a historical background, current status, and future perspectives on this emerging technology. MATERIAL AND METHODS An electronic search of the English language literature between the periods of January 1957 and June 2012 was performed by using PubMed/MEDLINE with the following specific search terms: CAD-CAM complete dentures, digital complete dentures, computer dentures, designed dentures, machined dentures, manufactured dentures, milled dentures, and rapid prototyping dentures. Additionally, the search terms were used on the Google search engine to identify current commercial manufacturers and their protocols. RESULTS A total of 1584 English language titles were obtained from the electronic database, and the systematic application of exclusion criteria resulted in the identification of 8 articles pertaining to computer-aided technology for complete dentures. Since the first published report in 1994, multiple authors have described different theoretical models and protocols for fabricating complete dentures with computer-aided technology. Although no clinical trials or clinical reports were identified in the scientific literature, the Google search engine identified 2 commercial manufacturers in the United States currently fabricating complete dentures with computer-aided design and computer-aided manufacturing (CAD/CAM) technology for clinicians world-wide. These manufacturers have definitive protocols in place and offer exclusive dental materials, techniques, and laboratory support. Their protocols contrast with conventional paradigms for fabricating complete dentures and allow the fabrication of complete dentures in 2 clinical appointments. CONCLUSIONS A body of scientific literature related to computer-aided technology for complete dentures is emerging. Significant advancements in this technology have now resulted in their commercial availability with shorter clinical protocols. However, prospective clinical trials with true clinical endpoints are necessary to validate this technology. This could affect dental education, patient care, research, and public health worldwide.

Retention forces of spherical attachments as a function of implant and matrix angulation in mandibular overdentures: An in vitro study

STATEMENT OF PROBLEM Nonparallel implants, when used to retain overdentures, may present a restorative challenge, particularly when using attachments. Premature wear of the components and loss of retention may be observed, resulting in increased maintenance. PURPOSE The purpose of this study was to compare the retentive behavior, over time, of spherical attachments when used in nonparallel and parallel implant scenarios in a cyclic testing mode. MATERIAL AND METHODS Thirty sets of 2-implant-supported overdenture models were evaluated: 4.0 x 13-mm implants (Astra-Tech Osseospeed) with 1.5-mm ball abutments (Astra-Tech) were used as the intraoral analog to the implants, and spherical attachments (Preci Clix) were used as the overdenture analog. Five different attachment and implant-abutment complex angulations were evaluated. Angulation was determined by deviation from the vertical reference plane. The groups consisted of the following: Group 0-0, 0-degree implants/0-degree attachments; Group 10-0, 10-degree implants/0-degree attachments; Group 15-0, 15-degree implants/0-degree attachments; Group 10-10, 10-degree implants/10-degree attachments; and Group 15-15, 15-degree implants/15-degree attachments. The specimens were subjected to cyclic loading (3500 cycles). Peak and valley retention loads were recorded at the first pull and then after every 100 cycles; therefore, 36 data points per specimen were recorded. Nonparametric analyses followed by post hoc analyses were conducted to test for differences in median peak load among groups (alpha=.05). RESULTS Peak load to dislodgment values for all groups ranged from 11.43 N to 23.56 N. Group 0-0 had the highest median retention value overall, 21.3 N, and Group 15-15 had the lowest median value, 17.3 N. Nonparametric analyses showed significant differences between Groups 0-0 and 15-15 (P=.014); and 10-0 and 15-15 (P=.002). CONCLUSIONS Within the limitations of this study, it was observed that there was a decrease in retention in the groups with 30-degree divergent implants and divergent attachments compared to the groups with parallel implants and parallel attachments. In general, retention varied from 11 N to 23 N, and attachment retention stabilized after initial loss in most groups.

The relationship of facial anatomic landmarks with midlines of the face and mouth

STATEMENT OF PROBLEM The importance of the midline is well known to dentists. Currently, there are no verifiable guidelines that direct the choice of specific anatomic landmarks to determine the midline of the face or midline of the mouth. PURPOSE The purpose of this study was to determine the hierarchy of facial anatomic landmarks closest to the midline of the face as well as midline of the mouth. MATERIAL AND METHODS Three commonly used anatomic landmarks, nasion, tip of the nose, and tip of the philtrum, were marked clinically on 249 subjects (age range: 21-45 years). Frontal full-face digital images of the subjects in smile were then made under standardized conditions. A total of 107 subjects met the inclusion criteria. Upon applying exclusion criteria, images of 87 subjects were used for midline analysis using a novel concept called the Esthetic Frame. Deviations from the midlines of the face and mouth were measured for the 3 clinical landmarks; the existing dental midline was considered as the fourth landmark. The entire process of midline analysis was done by a single observer and repeated twice. Reliability analysis and 1-sample t tests were conducted at alpha values of .001 and .05, respectively. RESULTS The results indicated that each of the 4 landmarks deviated uniquely and significantly (P<.001) from the midlines of the face as well as the mouth. CONCLUSIONS Within the limitations of the study, the hierarchy of anatomic landmarks closest to the midline of the face in smile was as follows: the midline of the oral commissures, natural dental midline, tip of philtrum, nasion, and tip of the nose. The hierarchy of anatomic landmarks closest to the midline of the oral commissures was: natural dental midline, tip of philtrum, tip of the nose, and nasion. These relationships were the same for both genders and all ethnicities classified.

Management of patients with excessive gingival display for maxillary complete arch fixed implant-supported prostheses

Maxillary complete arch fixed implant-supported prostheses are a popular treatment option for edentulous patients. Excessive gingival display or gummy smile in edentulous patients is relatively uncommon. However, many partially edentulous patients or completely dentate patients with compromised dentition and excessive gingival display may seek a fixed implant-supported prosthesis. Some of these patients may be candidates for immediate implant placement and insertion of the prosthesis, while others may carry over their preexisting excessive gingival display to the edentulous state for a variable period of time. Both types of patients require meticulous treatment planning and often require additional preprosthetic interventions before the placement of dental implants. This report provides an overview of the etiology, diagnosis, treatment planning, and options for management of patients with excessive gingival display who seek a maxillary complete arch fixed implant-supported prosthesis.

Techniques for incorporation of attachments in implant-retained overdentures with unsplinted abutments

A variety of techniques have been reported in the literature for the incorporation of attachments in implant-retained partial and complete overdentures with unsplinted or individual abutments. Three important elements that are necessary in describing any technique for incorporation of attachments are the type of final impression method (tissue-level impression, abutment-level impression, or implant-level impression), stage of overdenture fabrication (record base stage, denture-processing stage, or denture insertion stage) and nature of technique (direct or indirect). This article reviews 7 different techniques for the incorporation of attachments in implant-retained complete and partial overdentures. Discussion of indications, contraindications, advantages, and disadvantages of each technique is provided to aid the clinician in making an appropriate choice.

Changes in Lower Facial Height and Facial Esthetics with Incremental Increases in Occlusal Vertical Dimension in Dentate Subjects.

PURPOSE To determine if there are objective changes in lower facial height and subjective changes in facial esthetics with incremental increases in occlusal vertical dimension in dentate subjects. MATERIALS AND METHODS Twenty subjects of four different races and both sexes with a Class I dental occlusion had custom diagnostic occlusal prostheses (mandibular overlays) fabricated on casts mounted on a semi-adjustable articulator. The overlays were fabricated at 2-mm, 3-mm, 4-mm, and 5-mm openings of the anterior guide pin of a semi-adjustable articulator. Direct facial measurements were made between pronasale and menton on each subject while wearing the four different overlays. Thereafter, two digital photographs (frontal and profile) were taken for each subject at maximum intercuspation (baseline) and wearing each of the four mandibular overlays. The photographs of eight subjects were standardized and displayed in a random order to 60 judges comprising 30 laypeople, 15 general dentists, and 15 prosthodontists. Using a visual analog scale, each judge was asked to rate the facial esthetics twice for each of the 80 images. RESULTS For objective changes, although an anterior guide pin-lower facial height relationship of 1:0.63 mm was observed, the findings were not correlated (P>.20). For subjective changes, the visual analog scale ratings of judges were uncorrelated with increases in anterior guide pin opening up to 5 mm, irrespective of the judges background status or the sexes of the judges or the subjects (P>.80). CONCLUSIONS Incremental increases in anterior guide pin opening up to 5 mm did not correlate to similar increases in lower facial height. Additionally, it made no difference in a judges evaluation of facial esthetics irrespective of the judges background status (layperson, general dentist, or prosthodontist) or sex.

Differences in Lip Support with and without Labial Flanges in a Maxillary Edentulous Population. Part 1: Objective Analysis: Part 1: Objective Analysis

PURPOSE To study the objective differences in lip support using common facial soft tissue markers, when evaluating patients wearing a maxillary denture with a labial flange in comparison to an experimental flangeless denture. MATERIALS AND METHODS A total of 31 maxillary edentulous patients who were esthetically satisfied with their existing maxillary denture were recruited in this clinical study. The maxillary denture was then duplicated in clear acrylic resin. Two standardized full-face digital photographs (frontal and profile) were made with the duplicate denture in the mouth. The labial flange of the duplicate denture was then removed from first premolar to first premolar region, to create the experimental flangeless denture. It was returned to the oral cavity, and 2 additional full-face digital photographs were made. The differences between these images were studied using 5 facial anatomic markers (subnasale, labrale superior, stomion, nasolabial angle, lip thickness). A paired sample t-test was used to compare differences in measurements for various anatomic markers using an alpha value of 0.05. RESULTS For profile images, there were no statistically significant differences between photographs with and without a labial flange for anatomic markers- labrale superior and stomion (p < 0.05). There was a statistically significant difference for subnasale as well as the nasolabial angle but the magnitude of the difference was too small to be clinically significant (p < 0.05). For frontal images, there was no statistically significant difference in lip thickness between photographs with and without a labial flange. Additionally, there was no association between differences in measurements and patient-related factors such as gender and prior years of edentulism. CONCLUSIONS Removal of a labial flange in a maxillary denture resulted in minimal and clinically insignificant anatomic differences in lip support between flange and flangeless dentures, when analyzed in frontal and profile images.

Management of misangulated implants for a maxillary overdenture with spherical abutments: a clinical report.

Misangulated and malpositioned implants pose a significant challenge for the prosthodontic treatment of edentulous patients. Most reports of maxillary overdenture patients have described the use of a bar to splint malaligned implants, followed by successful fabrication of the prosthesis. Few reports have discussed the use of individual abutments in such situations. This clinical report describes the successful use of spherical/ball abutments for the management of 4 malaligned implants in the edentulous maxilla for an overdenture. The rationale and technique for the use of spherical abutments for overdenture fabrication in such situations are described.

Academy of Prosthodontics centennial: The educational roots of our specialty

The Academy of Prosthodontics was there at the beginning of prosthodontics as a specialty. In 1918, a few distinguished individuals saw the need to develop prosthetic techniques and concepts and formed the National Society of Denture Prosthetists. Renamed the Academy of Denture Prosthetics (ADP) in 1940, the organization recognized the need to study, investigate, and disseminate knowledge related to prosthodontics. As the discipline evolved, the need to establish prosthodontics as a specialty became apparent. In 1947, the first 5 specialties, oral surgery, orthodontics, pedodontia, periodontia, and prosthodontia were recognized by the American Dental Association House of Delegates (ADA HOD). The ADA Council on Dental Education (CDE) formally approved the American Board of Prosthodontics at the 1948 ADA House of Delegates, along with boards for oral surgery, pedodontia, and periodontia. The Academy of Prosthodontics sponsored the American Board of Prosthodontics (ABP) from its beginning in 1947. The ABP developed and administered the specialty certification examination. In 1965, the ADA HOD adopted the eligibility requirement that all individuals taking the board examination must complete