Differences in Lip Support with and without Labial Flanges in a Maxillary Edentulous Population. 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.

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 judge's 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 judge's evaluation of facial esthetics irrespective of the judge's background status (layperson, general dentist, or prosthodontist) or sex.

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.

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.

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.

A classification system of patients for esthetic fixed implant-supported prostheses in the edentulous maxilla.

Edentulous maxillary fixed rehabilitation using dental implants is challenging and requires meticulous planning because of anatomic variations and the importance of facial and dental esthetics. This article reviews the application of facial esthetics, lip support, smile lines, residual ridge position, tooth proportions, and tooth positions for different types of patients. Based on these parameters, a simple new classification system is proposed to classify patients into four categories, which will help facilitate an easier diagnostic and communicative system. It will also enable the clinician to understand when and why gingiva-colored prosthetic material is needed. Using this classification system, a stepwise method of diagnosis and management techniques are described in detail for each of the four classes. The proposed classification system has been based on an analysis of various successfully treated patients with a minimum follow-up period of 2 years.

Clinical experience of residents with RPD treatment in U.S. graduate prosthodontics programs.

This cross-sectional study was conducted to quantify the clinical experience of prosthodontic residents with cast metal removable partial denture (RPD) treatment based on their year of training, geographic location of the program, and nature of the program. A web-based survey consisting of five questions was e-mailed to program directors from forty-two programs across the United States. A 62 percent response rate was obtained (26/42). Thirteen of the programs (50 percent of respondents) stipulated a specific number of RPDs to be done prior to completion of the program. Clinical experience of residents varied vastly based on year of training, geographic location of the program, and nature of the program. Prosthodontic residents from southern states, university-based programs, and public school programs had more clinical experience than residents from other programs. The average clinical experience for a prosthodontic resident during three years of training was eight traditional RPDs and two implant-supported RPDs. This is the first study done exploring this topic and provides baseline information on residents' clinical experience in RPD treatment. Future studies will determine educational trends and reassess this portion of the curriculum in graduate prosthodontics.

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.

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.

A comparison of debonding strengths of four metal-ceramic systems with and without opaque porcelain.

STATEMENT OF PROBLEM: When performing an adjustment on metal-ceramic restorations, opaque porcelain may become exposed, particularly on the lingual surface of maxillary anterior teeth. It is generally believed that exposed opaque porcelain can be more abrasive and destructive to an opposing dentition than body porcelain, and that these teeth may require restoration as a consequence. PURPOSE: This study compared the debonding strengths of 2 types of porcelain, with and without opaque porcelain, to 2 types of dental casting alloys. MATERIAL AND METHODS: Two porcelain systems, Ceramco3 and Vita 900, and 2 metal alloys, a high noble (Encore) and a base metal (Duceranium U), were used to fabricate and test 56 flexure bars in accordance with ISO 9693:1999(E): Metal-Ceramic Dental Restorative Systems. Half of the bars received opaque porcelain prior to body porcelain additions, and the other half did not. The metal-ceramic debonding strength was determined by using a 3-point flexure apparatus and a mechanical testing device (Instron). A center load was applied at a crosshead speed of 1.5 mm/min(-1) until debonding occurred. In addition to the load-versus-displacement curve, a precision measurement microphone was used to assist in ascertaining the point in time when debonding occurred. Since the sound analysis and the mechanical test were started simultaneously, the debonding load could be more accurately determined. Data were statistically analyzed using 3-way analysis of variance, and all pairwise multiple comparisons were made with the Tukey HSD test (alpha=.05). RESULTS: The difference in mean debonding strength values for opaqued and non-opaqued flexure bars were statistically significant (P=.028). The mean debonding strength values (MPa) for each metal-ceramic system were as follows: Encore-Opaque-Ceramco3 (EOC), 31.43 +/- 6.92(a); Encore-Opaque-Vita 900 (EOV), 30.37 +/- 3.25(a); Duceranium U-No Opaque-Ceramco3 (DNC), 29.20 +/- 6.97(a); Duceranium U-Opaque-Ceramco3 (DOC), 26.61 +/- 4.98(a); Duceranium U-Opaque-Vita 900 (DOV), 26.15 +/- 4.29(a); Encore-No Opaque-Vita 900 (ENV), 25.45 +/- 4.04(a); Encore-No Opaque-Ceramco3 (ENC), 23.96 +/- 4.14(a); Duceranium U-No Opaque-Vita 900 (DNV), 22.88 +/- 6.15(a). Identical superscript letters denote no significant difference among groups. The precision measurement microphone resulted in selection of a debonding strength/crack initiation load that was lower than the peak load recorded during strength testing. CONCLUSION: Initial debonding during crack initiation strength testing may not always correspond to the peak load recorded, but rather to the point on the load-versus-displacement curve beyond which the relationship is no longer a straight line. Presence of opaque porcelain generally increased the debonding strength for metal-ceramic systems; however, opaque porcelain may not be necessary for a clinically acceptable metal-ceramic bond for some metal-ceramic systems.

Surgical and prosthetic planning for a two-implant-retained mandibular overdenture: a clinical report.

A 2-implant-retained mandibular overdenture is considered by some to be the standard of care for mandibular edentulism. Compared to a conventional complete denture, an implant-retained overdenture requires more thorough planning. Careful consideration is necessary regarding the 3-dimensional orientation of the implants to ensure adequate horizontal and vertical space for prosthetic components. This clinical report describes a patient with a compromised mandibular overdenture in whom the position of the existing implants yielded insufficient space for prosthetic components. This report describes the concepts for treatment planning prior to fabricating a new mandibular overdenture, including considerations for the surgical removal of the existing implants, alveoloplasty to create the necessary space for prosthetic components, and placement of the new implants to ensure an esthetic and functional prosthesis.

Effect of implant angulation upon retention of overdenture attachments.

INTRODUCTION: Overdentures supported and retained by endosteal implants depend upon mechanical components to provide retention. Ball attachments are frequently described because of simplicity and low cost, but retentive capacity of these components may be altered by a lack of implant parallelism. PURPOSE: The aim of this in vitro study was to investigate the retention of gold and titanium overdenture attachments when placed on ball abutments positioned off-axis. METHODS AND MATERIALS: Four ball abutments were hand-tightened onto ITI dental implants and placed in an aluminum fixture that allowed positioning of the implants at 0 degrees, 10 degrees, 20 degrees, and 30 degrees from a vertical reference axis. Gold and titanium matrices were then coupled to the ball abutments at various angles and then subjected to pull tests at a rate of 2 mm/second; the peak loads of release (maximum dislodging forces) were recorded and subjected to statistical analyses. A balanced and randomized factorial experimental design testing procedure was implemented. RESULTS: Statistically significant differences in retention of gold matrices were noted when ball abutments were positioned at 20 degrees and 30 degrees , but not at 0 degrees and 10 degrees. Statistically significant differences were noted among the titanium matrices employed for the testing procedure, as well as for the 4 ball abutments tested. Angle was not a factor affecting retention for titanium matrices. CONCLUSIONS: (1) The gold matrices employed for the testing procedures exhibited consistent values in retention compared to titanium matrices, which exhibited large variability in retention. (2) Angle had an effect upon the retention of gold matrices, but not for titanium matrices.

Evaluation of margin angles of collarless metal ceramic restorations.

This study was designed to measure the porcelain margin angles of completed collarless metal ceramic restorations and determine if these angles correspond to the most frequently recommended porcelain margin angle of 90 degrees. A sample of 99 metal ceramic restorations with porcelain labial margins were evaluated. A 1.0 mm slice taken from the midfacial impression of each restoration was evaluated by tooth location with a stereomaster microscope and the angle of the labial porcelain margin was calculated. The comparison of margin angles by tooth location showed no statistical difference between the groups. Comparison of the average margin angle with the most suggested 90-degree angle was analyzed with a One-Sample t-test and found to be statistically significant (p = 0.000). Although the majority of dental schools teach the shoulder preparation for collarless metal ceramic restorations, only 43% of the restorations measured fell within 10 degrees of this standard.

Patient self-reported satisfaction with maxillary anterior dental implant treatment.

PURPOSE: Dental implants are accepted as a successful alternative to conventional fixed and removable prostheses for the treatment of partial or complete edentulism. However, there have been few studies of the success of implants from the patients' perspective. The purpose of this study was to assess patient overall satisfaction with the outcome of treatment with maxillary anterior implants. MATERIALS AND METHODS: A self-administered mailed questionnaire, which was developed for this project, and a data abstraction form, which was designed based on information available from the corresponding dental records of 123 eligible subjects, were utilized to survey implant patients. RESULTS: Seventy-eight of 123 eligible subjects responded to the mailed, self-administered, structured questionnaire. Twelve of the 24 questionnaire variables demonstrated statistically significant bivariate associations with the dependent variable "overall patient satisfaction." Five variables--implant position, definitive restoration shape, appearance, effect on speech, and chewing capacity--were strongly associated with overall satisfaction. No demographic or treatment-related, dental record-abstracted variable, of the 25 that were examined, was statistically significant. DISCUSSION: The practitioner who provides implant restorations should be aware of the multidimensional aspects of patient satisfaction with implant treatment. This study suggests that patient satisfaction with key elements influences the overall acceptance of maxillary anterior implant prostheses, which are esthetically critical. Communication between dentist and patient is important to achieve optimal results that will be satisfactory to both. Discussion of treatment limitations may also help patients to develop realistic expectations of the final result. CONCLUSIONS: In this limited investigation, patient satisfaction with implant position, restoration shape, overall appearance, effect on speech, and chewing capacity were critical for patient overall acceptance of the dental implant treatment.

Twenty years of progress in implant prosthodontics.

Prosthodontic focus on the restoration of osseointegrated dental implants has evolved dramatically in the last 20 years. Many of the original guiding principles for restoring implants have changed and/or disappeared altogether, and new ideas have taken their place. It is appropriate that this evolution be examined with a 2-fold focus. First, the art and science of prosthodontics as it relates to dental implants today is the result of very real and important lessons learned during the past 2 decades. Second, an appreciation of the history of implant prosthodontics as it relates to osseointegration gives insight into the future direction of research and clinical exploration aimed at continually improving the state of the art and, ultimately, the quality of care provided to patients. This article reviews what the authors consider the most important aspects of the evolution of osseointegrated implants. Pertinent literature was selected for citation, but the discussion does not represent a comprehensive review of the literature.