Randomized controlled multi-centre study comparing shorter dental implants (6 mm) to longer dental implants (11-15 mm) in combination with sinus floor elevation procedures: 10-year data.

AIM: To compare implant survival and complication rates between shorter and standard-length implants with sinus augmentation and restored with single crowns, at 10 years of loading. MATERIALS AND METHODS: One-hundred and one patients (137 implants) with a ridge height of 5-7 mm in the posterior maxilla were randomly assigned to two treatment modalities: shorter implants (6 mm) (group short [GS]) or standard-length implants (11-15 mm) with sinus grafting (group graft [GG]). Following the insertion of final restorations, patients were regularly recalled for up to 10 years. Assessed outcomes encompassed implant survival, marginal bone levels (MBLs), biological and technical parameters and patient-reported outcome measures (OHIP-49 = Oral Health Impact Profile). Non-parametric statistical analysis was used to analyse the data. RESULTS: For the 5- to 10-year follow-up period, 77 patients with 105 implants (GS: 36 patients/48 implants; GG: 41/57) were available for re-examination (drop-out rate 21%). Implant survival rates at the patient level were 96.0% (GS; 2 failures) and 100% (GG) (inter-group p = .24). Median MBLs amounted to 0.00 mm (min 0.00; max 3.25; GS) and 0.00 mm (min 0.00; max 4.55; GG) (inter-group p = .73). Technical complications predominantly occurred within the first 5 years (inter-group p > .05). Peri-implantitis rates were 4.2% (GS) and 13.3% (GG) (intergroup p = .37). Median OHIP-49 scores were 7.00 (0.00; 39.00; GS) and 9.00 (0.00; 196; GG) (inter-group p = .61) at 10 years. CONCLUSIONS: Based on similar 10-year implant survival rates, reduced patient morbidity and lower costs, the use of shorter dental implants might well serve as an alternative treatment concept to longer implants placed in conjunction with sinus grafting for patients with a limited ridge height in the posterior maxilla. Study register: https://clinicaltrials.gov/ct2/show/NCT01030523.

Comparison of electronic versus mechanical torque-limiting devices for dental implants: An in vitro study.

PURPOSE: To determine the accuracy of new electronic torque-limiting devices (ET) when compared to new and used conventional-style beam-type (BT) mechanical torque-limiting devices and hand-piece style (HS) mechanical torque-limiting devices. The secondary purpose was to compare any difference in accuracy between new and used mechanical torque-limiting devices, and any difference in accuracy when used on a straight versus an angled screw channel abutment. MATERIALS AND METHODS: A total of five torque-limiting devices were used to obtain 2000 readings under standardized conditions. An implant analog was fastened into a digital torque meter, to which an abutment was connected. Pre-determined torque values of 15 Ncm and 35 Ncm were applied, and actual torque values were recorded. A straight and an angled abutment were used to record 1000 readings each using the five torque-limiting devices. An overall Kruskal-Wallis test was applied to compare the median deviation among devices followed by a pairwise comparison ( = 0.05). RESULTS: For a target torque value of 15 Ncm on a straight abutment, the electronic device (ET) was statistically more accurate than the beam type (BT) new (p < 0.001) and used (p < 0.048) devices but less accurate than the hand-piece style (HS) used device (p < 0.001). On an angled abutment for a target value of 15 Ncm, the electronic device (ET) was statistically more accurate than hand-piece style (HS) new and used devices (p < 0.001). For a target torque value of 35 Ncm on a straight abutment, the ET was statistically more accurate than the HS new device (p < 0.001) but less accurate than the BT new device (p < 0.001). On an angled abutment for a target value of 35 Ncm, the electronic device (ET) was statistically less accurate than the beam-type (BT) new device (p < 0.001), the beam-type (BT) used device (p = 0.001), and the hand-piece style (HS) used device (p < 0.001). The electronic device (ET) was the only device accurate within the ISO standard of accuracy of 6% for each of the target torque value/abutment design combinations. There was no statistically significant difference related to the type of abutment used (angled vs. straight). CONCLUSIONS: Electronic torque limiting devices (ET) are an acceptable method for delivering torque for implant restorations for straight and angled abutments at 15 Ncm and 35 Ncm torque values. Conventional style beam-type (BT) mechanical torque-limiting devices are a simple, predictable, validated, and inexpensive tool for delivering accurate torque at 15 Ncm and 35 Ncm torque values. The hand-piece style (HS) mechanical torque-limiting devices are predictable to deliver 15 Ncm torque values.

Custom Made Device for Removal of Removable Partial Denture in a Patient with Manual Impairment.

Manual impairment could be part of the clinical presentation of a number of systemic conditions or traumas. Inability to successfully remove a removable partial denture is one of the contraindications of this type of treatment. This report presents a technique for fabrication of a custom device made chairside to assist a manually impaired patient due to osteoarthritis with the removal of a removable mandibular prosthesis. This technique could allow patients with similar conditions to replace their missing teeth with removable partial dentures, in cases where a fixed restoration is not an option.

Prosthodontic Rehabilitation of a Patient with Hypophosphatasia Using Dental Implants: A Case Report with Seven Years Follow-Up.

Hypophosphatasia is a rare metabolic inherited dento-osseous disorder. Although there is some available literature on various dental characteristics of hypophosphatasia patients, few reports focus on the effects of hypophosphatasia on the permanent dentition and prosthodontic rehabilitation, particularly in relation to the use of dental implants. This paper reports a case with hypophosphatasia and prosthodontic rehabilitation using dental implants with 7-year follow-up.

Randomized controlled multicentre study comparing short dental implants (6 mm) versus longer dental implants (11-15 mm) in combination with sinus floor elevation procedures: 5-Year data.

AIM: To compare the implant survival rate between short dental implants and standard length implants placed in combination with bone grafting at 5 years of loading. METHODS: This multicentre study enrolled 101 patients (137 implants) with a posterior maxillary bone height of 5-7 mm. Patients randomly received either short implants (6 mm; GS) or long implants (11-15 mm) with sinus grafting (GG). Six months later, implants were loaded with single crowns and patients re-examined at 1, 3 and 5 years of loading. Outcomes included: implant survival, marginal bone levels (MBLs), biological and technical parameters and patient-reported outcome measures (OHIP-49 = Oral Health Impact Profile). Statistical analysis was performed using a non-parametric approach. RESULTS: At 5 years, 90 patients (124 implants; GS: 60; GG: 64) were re-examined (drop-out rate 10%). Patient-level implant survival rates were 98.5% (GS; 1 implant failure) and 100% (GG; p = 0.49). Mean MBLs were 0.54 mm ± 0.87 (GS) and 0.46 mm ± 1.00 (GG; p = 0.34). Biological and technical parameters were not significantly different (p > 0.05). Median overall OHIP-49 scores improved significantly up to 5 years in both groups (GS: p = 0.03; GG: p = 0.00; intergroup comparison p = 0.11). CONCLUSIONS: Both treatment modalities were suitable for implant therapy in the atrophied posterior maxilla revealing no differences in terms of survival rates, marginal bone levels (changes), patient-reported outcomes and technical/biological complications.

Number of implants placed for complete-arch fixed prostheses: A systematic review and meta-analysis.

OBJECTIVES: The main purpose of this systematic review was to evaluate outcomes related to the number of implants utilized to support complete-arch fixed prostheses, both for the maxilla and the mandible. MATERIALS AND METHODS: This review followed the reporting guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A focused question using the PICO format was developed, questioning whether "In patients with an implant supported fixed complete dental prosthesis, do implant and prosthetic survival outcomes differ between five or more compared to fewer than five supporting implants?". A comprehensive search of the literature was formulated and performed electronically and by hand search. Two independent reviewers selected the papers and tabulated results. Primary outcomes analyzed were implant and prosthesis survival. Implant distribution, loading, and type of retention were observed as secondary outcomes, as they relate to the number of implants. A meta-analysis was performed to compare results for studies by number of implants. RESULTS: The search strategy identified 1,579 abstracts for initial review. Based on evaluation of the abstracts, 359 articles were identified for full-text evaluation. From these, 93 were selected and included in this review, being nine RCTs, 42 prospective and 42 retrospective. Of the 93 selected studies, 28 reported number of implants for the maxilla, 46 for the mandible, and 19 for both maxilla and mandible. The most reported number of implants for the "fewer than five" group is 4 for the maxilla, and 3 and 4 for the mandible, whereas for the "five or more" implants group, the most reported number of implants was 6 for the maxilla and 5 for the mandible. No significant differences in the primary outcomes analyzed were identified when fewer than five implants per arch were compared with five or more implants per arch (p > 0.05), in a follow-up time ranging from 1 to 15 years (median of 8 years). CONCLUSIONS: Evidence from this systematic review and meta-analysis suggests that the use of fewer than five implants per arch, when compared to five or more implants per arch, to support a fixed prosthesis of the completely edentulous maxilla or mandible, present similar survival rates, with no statistical significant difference at a p < 0.05 and a confidence interval of 95%.

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.

Short dental implants (6 mm) versus long dental implants (11-15 mm) in combination with sinus floor elevation procedures: 3-year results from a multicentre, randomized, controlled clinical trial.

AIM: To test whether the use of short dental implants (6 mm) results in an implant survival rate similar to that with longer implants (11-15 mm) in combination with sinus grafting. METHODS: This multicentre study enrolled 101 patients with partial edentulism in the posterior maxilla and a remaining bone height of 5-7 mm. Included patients were randomly assigned to receive short implants (6 mm; GS/group short) or long implants (11-15 mm) simultaneously with sinus grafting (GG/group graft). Six months after implant placement (IP), implants were loaded with single crowns (PR) and patients were re-examined yearly thereafter. Assessed outcomes included: implant survival, marginal bone level changes (MBL), probing pocket depth (PPD), bleeding on probing (BoP) and plaque accumulation (PCR) during 3 years of loading as well as recording of any adverse effects. In addition to descriptive statistics, statistical analysis has been performed for the two treatment modalities using a non-parametric approach. RESULTS: In 101 patients, 137 implants were placed. At the 3-year follow-up (FU-3), 94 patients with 129 implants were re-examined. The implant survival rate was 100% in both groups. MBL at FU-3 was 0.45 mm (GG) and 0.44 mm (GS) (p > 0.05). A statistically significant loss of MBL was observed in both GG (-0.43 ± 0.58 mm) and GS (-0.44 ± 0.56 mm) from IP to FU-3, and from PR to FU-3 in GG (-0.25 ± 0.58 mm) but not in GS (-0.1 ± 0.54 mm). PCR and BoP at FU-3 did not show any difference between the groups but for PPD (p = 0.035). CONCLUSIONS: Within the limitations of this study, implants with a length of 6 mm as well as longer implants in combination with a lateral sinus lift may be considered as a treatment option provided a residual ridge height of 5-7 mm in the atrophied posterior maxilla is present.

Clinical significance of immediate mandibular lateral translation: A systematic review.

STATEMENT OF PROBLEM: Immediate mandibular lateral translation (IMLT) has been widely described in theory, but its clinical significance in prosthodontics and restorative dentistry is not clear. PURPOSE: The purpose of this study was to systematically review the existing literature to identify the clinical significance of IMLT (immediate side shift). MATERIAL AND METHODS: An electronic search for articles in the English language literature was performed independently by multiple investigators using a systematic search process with the PubMed search engine. After applying predetermined inclusion and exclusion criteria, the final list of studies was analyzed to identify the clinical significance of IMLT. RESULTS: The initial electronic search yielded 858 titles. The systematic application of the inclusion and exclusion criteria eventually produced 23 studies addressing IMLT in 914 human participants. Eleven studies reported use of voluntary movements, 5 articles reported use of only induced movements, 2 studies reported use of both voluntary and induced movements, and 5 articles did not report the recording method. The amount of IMLT reported ranged from 0 to 3 mm with minimal clarity among authors on the exact description of IMLT. No studies reported on any clinical implication (harm or benefit to patients or clinicians) of incorporating IMLT in diagnosis and treatment planning. CONCLUSIONS: This systematic review did not identify any scientific evidence on the clinical implications of IMLT. Furthermore, there is a lack of clear terminology related to IMLT and the timing of the side shift, occurrence of IMLT on the working versus nonworking condyle, and induced versus noninduced methods of recording and measuring. Current scientific evidence does not support the need to include IMLT as a factor when prosthodontic or restorative treatment is planned and executed.

Prospective cohort pilot study of 2-visit CAD/CAM monolithic complete dentures and implant-retained overdentures: Clinical and patient-centered outcomes.

STATEMENT OF PROBLEM: Presently, no studies have evaluated clinical outcomes or patient-centered outcomes for complete dentures fabricated with computer-aided design and computer aided manufacturing (CAD/CAM) technology. PURPOSE: The purpose of this prospective cohort pilot study was to evaluate the clinical and patient-centered outcomes for CAD/CAM monolithic dentures fabricated in 2 visits. MATERIAL AND METHODS: Twenty participants with an existing set of maxillary complete dentures opposing either mandibular complete dentures or implant-retained overdentures that required replacement were recruited in this study. A 2-visit duplicate denture protocol was used to fabricate 40 arches of monolithic dentures with CAD/CAM technology. A 100-mm visual analog scale (VAS) instrument was then used to record 12 outcomes at baseline and at 1-year follow-up. Predetermined values were assigned to grade the VAS rating of each outcome as favorable (70.1-100) and unfavorable (≤70). Favorable ratings were sub-divided as excellent (90.1-100), good (80.1-90), and fair (70.1-80). The clinical outcomes were evaluated independently by 2 experienced prosthodontists at baseline and at 1-year follow-up. Patients evaluated the corresponding patient-centered outcomes during the same time intervals. Additional descriptive variables were also recorded. Each clinical and patient-centered outcome was summarized by medians and ranges. Differences in all ratings recorded at baseline and at 1 year were tested by 1-sided sign test (α=.05). RESULTS: Of 20 participants, 3 were lost to follow-up, and 3 were unsatisfied with the digital dentures and withdrew from the study. These 3 participants were considered treatment failures. Of the 14 remaining participants, 9 had implant-retained mandibular overdentures, and 5 had conventional mandibular complete dentures. For clinical outcomes, the 12 studied outcomes were favorably evaluated by the 2 prosthodontist judges at the 1-year follow-up. Evaluations showed minimal differences between baseline and 1 year. An average of 5 emails (0-11) per patient were sent to the laboratory technicians to communicate the improvisation the CAD design of the dentures. An average of 3.3 denture adjustments were needed after insertion (0-10) during the 1-year period. For patient-centered outcomes, median ratings of all 14 participants indicated each of the 12 studied outcomes was favorable at the 1-year recall. Statistically significant improvements in patient ratings from baseline to 1 year were observed for the absence of denture sore spots and treatment time to make the dentures (P<.05). Minor complications related to loss of retention, excessive wear of teeth and the need for additional visits were observed in 5 participants. No other adverse clinical outcomes related to the CAD/CAM dentures were noted in the 14 evaluated participants, and all dentures were intact and in good condition at the 1-year follow-up. CONCLUSIONS: Clinical and patient-centered outcomes for CAD/CAM monolithic dentures fabricated using a 2-visit protocol were evaluated favorably at a 1-year follow-up. However, the proportion of excellent and good ratings for overall satisfaction and assessment was higher for patients than clinicians. A considerable amount of the clinician's time and effort was devoted to aiding in the digital process for the fabrication of CAD/CAM dentures.

Randomized controlled multicenter study comparing short dental implants (6 mm) versus longer dental implants (11-15 mm) in combination with sinus floor elevation procedures. Part 2: clinical and radiographic outcomes at 1 year of loading.

AIM: To compare, clinically and radiographically, short dental implants (6 mm) to long implants (11-15 mm) placed with sinus grafting. METHODS: Participants with 5-7 mm of bone height in the posterior maxilla were randomly allocated to receive short implants (GS) or long implants with sinus grafting (GG). Implants were loaded with single crowns 6 months after placement (PR). Patients were re-evaluated 12 months after loading (FU-1). Outcome variables included: Implant survival rate (CSR), marginal bone level alteration (MBL), periodontal probing depth (PPD), bleeding on probing (BoP), plaque control record (PCR) and crown-to-implant ratios (C/I). Statistical analysis was performed using parametric tests. RESULTS: In 97 subjects, 132 implants were re-evaluated at FU-1. The CSR was 100%. The MBL from implant placement (IP) to (PR) was -0.22 ± 0.4 mm for GG and -0.3 ± 0.45 mm for GS (p < 0.001). MBL from IP to FU-1 was -0.37 ± 0.59 mm for GG and -0.22 ± 0.3 mm for GS (p < 0.001). Intergroup comparisons showed non-significant differences for MBL (p > 0.05), PPD (p = 1) and PCR (p = 0.09). BoP was higher in the GS (p = 0.04). The C/I was 0.99 ± 0.17 for GG and 1.86 ± 0.23 for GS (p < 0.001). No correlation was observed between C/I and MBL, (GG: p = 0.13; GS: p = 0.38). CONCLUSIONS: Both treatment modalities provided similar outcomes.

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.

Classification of maxillectomy defects: a systematic review and criteria necessary for a universal description.

STATEMENT OF PROBLEM: Maxillectomy defects are complex and involve a number of anatomic structures. Several maxillectomy defect classifications have been proposed with no universal acceptance among surgeons and prosthodontists. Established criteria for describing the maxillectomy defect are lacking. PURPOSE: This systematic review aimed to evaluate classification systems in the available literature, to provide a critical appraisal, and to identify the criteria necessary for a universal description of maxillectomy and midfacial defects. MATERIAL AND METHODS: An electronic search of the English language literature between the periods of 1974 and June 2011 was performed by using PubMed, Scopus, and Cochrane databases with predetermined inclusion criteria. Key terms included in the search were maxillectomy classification, maxillary resection classification, maxillary removal classification, maxillary reconstruction classification, midfacial defect classification, and midfacial reconstruction classification. This was supplemented by a manual search of selected journals. After application of predetermined exclusion criteria, the final list of articles was reviewed in-depth to provide a critical appraisal and identify criteria for a universal description of a maxillectomy defect. RESULTS: The electronic database search yielded 261 titles. Systematic application of inclusion and exclusion criteria resulted in identification of 14 maxillectomy and midfacial defect classification systems. From these articles, 6 different criteria were identified as necessary for a universal description of a maxillectomy defect. Multiple deficiencies were noted in each classification system. Though most articles described the superior-inferior extent of the defect, only a small number of articles described the anterior-posterior and medial-lateral extent of the defect. Few articles listed dental status and soft palate involvement when describing maxillectomy defects. CONCLUSIONS: No classification system has accurately described the maxillectomy defect, based on criteria that satisfy both surgical and prosthodontic needs. The 6 criteria identified in this systematic review for a universal description of a maxillectomy defect are: 1) dental status; 2) oroantral/nasal communication status; 3) soft palate and other contiguous structure involvement; 4) superior-inferior extent; 5) anterior-posterior extent; and 6) medial-lateral extent of the defect. A criteria-based description appears more objective and amenable for universal use than a classification-based description.

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.

The RPH clasp assembly: a simple alternative to traditional designs.

One of the popular designs for the distal extension partial removable dental prosthesis is the RPI clasp assembly. A modification of the RPI clasp assembly is introduced. It incorporates a mesial rest (R), proximal plate (P), and a horizontal retentive arm (H-RPH). This clasp assembly provides benefits of the RPI clasp and can be used in clinical situations where the RPI clasp is contraindicated.

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.