Carl F. Driscoll

The change in retentive values of locator attachments and hader clips over time.

PURPOSE The aim of this study was to examine early changes in retentive values of implant overdenture attachments during multiple pulls. MATERIALS AND METHODS Two implant attachment systems (Hader bar and clip, Locator system) were used in this study. The experimental groups were divided into yellow Hader clips, white Locator attachments, and green Locator attachments. Each group consisted of 21 matrix attachments. The attachments were placed into a custom-made acrylic resin block seated passively on another acrylic block containing a Hader bar or two Locator abutments with different angulations. Each attachment was subjected to 20 consecutive pulls using a universal testing machine. The peak load-to-dislodgement of the attachments after each pull was documented, and the percent reduction of the peak load-to-dislodgement was calculated. One-way ANOVA and Tukeys honestly significant difference test were used for data analyses. A p < or = 0.05 was considered significant. RESULTS There was a significant difference in the percent reduction in peak load-to-dislodgement between the attachments after the first pull (p= 0.005) and after the final pull (p= 0.0001). The yellow Hader clips exhibited the least percent reduction in peak load-to-dislodgement (6.50 +/- 3.59%) after the first pull, followed by the white Locator attachments (8.60 +/- 4.42%); the green Locator attachments exhibited the greatest reduction (11.05 +/- 4.94%). CONCLUSION The results of this in vitro study demonstrate that retentive values of the Locator attachments are reduced significantly after multiple pulls. Although this reduction might not be noticeable to the patient, it is recommended that the clinician place and remove the overdenture multiple times before delivery.

The effect of denture cleansing solutions on the retention of pink Locator attachments: an in vitro study.

PURPOSE To evaluate the changes in retention of pink Locator attachments after exposure to various denture cleansers. MATERIALS AND METHODS Six groups (20 pairs each) of pink Locator attachments (3.0 lb. Light Retention replacement patrix attachments) were soaked for the equivalent of 6 months of clinical use in the following solutions: Water (control), Polident Regular, Efferdent, 6.15% sodium hypochlorite (NaOCL, 1:10 dilution), Polident Overnight, and Cool Mint Listerine mouthwash. A universal testing machine set at a crosshead speed of 2 in/min was used to perform one pull. The peak load-to-dislodgement was recorded to reflect changes in the retention of the Locator attachments after soaking. Data were analyzed by one-way ANOVA followed by Tukeys Honestly Significant Difference test. A p< or = 0.05 was considered significant. RESULTS Denture cleansing solutions significantly affected the retentive values of pink Locator attachments (F = 344.3, p< or = 0.0001). Cool Mint Listerine mouthwash increased the retentive values of the attachments (51.10 +/- 5.31 N) when compared to the control group (45.25 +/- 3.49 N). There was no significant difference in the retentive values of attachments soaked in Polident Regular or Polident Overnight when compared to the control group. Efferdent caused a small reduction in the retentive values (40.81 +/- 2.56 N) and most importantly, diluted NaOCl caused a large reduction in the retentive values (7.83 +/- 2.50 N) of pink Locator attachments. In addition, Cool Mint Listerine mouthwash caused blue discoloration of the Locator attachments, and NaOCl caused whitening and softening of the pink Locator attachments. CONCLUSION Cool Mint Listerine and Efferdents small effect on the retentive values of the Locators might be clinically unimportant; however, NaOCl caused a large reduction in the retentive values of the attachments. Because of their effect on retentive values and on the color of the Locator attachments, NaOCl and Cool Mint Listerine are not recommended. These results should be interpreted clinically with caution, realizing that different results may be obtained when fatigue stress during function and multiple pulls (in vivo) are combined with the chemical action of denture cleansers.

Comparison of cutting efficiencies between electric and air-turbine dental handpieces

STATEMENT OF PROBLEM Dentistry is gravitating toward the increased use of electric handpieces. The dental professional should have sufficient evidence to validate the switch from an air-turbine handpiece to an electric handpiece. However, there is little research quantifying the cutting efficiency of electric and air-turbine handpieces. Studies that do quantify cutting efficiency typically do so with only a single material. PURPOSE The purpose of this study was to compare the cutting efficiency of an electric handpiece and an air-turbine handpiece, using various materials commonly used in dentistry. MATERIAL AND METHODS Seven materials: Macor (machinable glass ceramic), silver amalgam, aluminum oxide, zirconium oxide, high noble metal alloy, noble metal alloy, and base metal alloy, were each cut with a bur 220 times; 110 times with an electric handpiece, and 110 times with an air-turbine handpiece. The weight difference of the material was calculated by subtracting the weight of the material after a cut from the weight of the material before the cut. The cutting efficiency was calculated by dividing the weight difference by the duration of the cut (g/s). Data were analyzed by a 2-way analysis of variance followed by Tukeys Honestly Significant Difference (HSD) test (alpha=.05). RESULTS The electric handpiece cut more efficiently than the air-turbine handpiece (F=3098.9, P<.001). In particular, the high noble metal alloy, silver amalgam, and Macor were cut more efficiently with the electric handpiece (0.0383 +/-0.0002 g/s, 0.0260 +/-0.0002 g/s, and 0.0122 +/-0.0002 g/s, respectively) than with the air-turbine handpiece (0.0125 +/-0.0002 g/s, 0.0142 +/-0.0002 g/s, and 0.008 +/-0.0002 g/s, respectively). CONCLUSIONS The electric handpiece is more efficient at cutting various materials used in dentistry, especially machinable glass ceramic, silver amalgam, and high noble alloy, than the air-turbine handpiece.

The effect of a denture adhesive on the colonization of candida species in vivo

PURPOSE The purpose of this study was to evaluate the effect of a single denture adhesive on oral quantities of Candida species in vivo by determination of absolute and proportional counts of Candida species on dentures and in saliva of individuals who used this denture adhesive for a period of 14 days. MATERIALS AND METHODS Samples were collected from saliva and maxillary dentures of 12 patients who wore existing dentures without adhesives for 2 weeks, then wore dentures with adhesive (Poly Grip Free; Glaxo Smith Kline, U.K.) for 2 weeks. Periodically, maxillary dentures were sampled by adding saline to the intaglio surface, dispersing by sonication and removing aliquots for culturing. These aliquots and saliva were diluted and plated in duplicate on bismuth sulfite, glycerine, and glucose yeast agar (Biggy) for recovery of Candida and on trypticase soy agar for total viable counts (TVC) of the microbiota. After 72 hours of incubation at 37 degrees C in air with 10% CO(2), colony-forming units were enumerated. In each individual, absolute counts of Candida and TVC, and proportional counts of Candida relative to TVC were compared and statistically evaluated during the periods of no adhesive use (control) and adhesive use (test). RESULTS There were no statistically significant differences between the test and control periods for recovery of total Candida or TVC in saliva or on dentures, or the percent of Candida relative to TVC in saliva or on dentures. CONCLUSION Within the limitations of this study, the data suggested that the denture adhesive tested did not significantly alter the denture microbiota during the 14-day trial period.

The Effect of Denture Cleansing Solutions on the Retention of Pink Locator Attachments after Multiple Pulls: An In Vitro Study

PURPOSE The effect of denture cleansing solutions and multiple pulls on the retention of pink Locator patrices was studied. MATERIALS AND METHODS Five groups of pink Locator attachments (3.0 lb. Light Retention replacement patrix attachments; five in each group) were soaked for the equivalent of 6 months of clinical use in the following solutions: water (control), Efferdent, Polident Overnight, 6.15% sodium hypochlorite (NaOCL, 1:10 dilution), and Listerine mouthwash. A universal testing machine set at a 2 in/min crosshead speed was used to perform 548 pulls (548 cycles of insertion and removal). The reduction in load to dislodgement (retention) after the initial pull and the final pull and the percent reduction in retention after 6 months were compared between the groups using a one-way ANOVA followed by Tukeys Honestly Significant Difference (HSD) Test (α= 0.05). RESULTS Denture cleansing solutions significantly reduced the retentive values of pink Locator attachments after the initial pull (F = 17.435, p < 0.0001). The retentive values of Efferdent, Listerine, Polident Overnight, and water were significantly higher than the retentive value of the attachments soaked in NaOCl. After 6 months of simulated use (548 pulls), the four denture cleansing solutions had significant effects on the retentive values of pink Locator attachments (F = 5.855, p = 0.003). The retentive values for attachments soaked in NaOCl (7.29 ± 1.0 N) were significantly lower than those of attachments soaked in Listerine (15.82 ± 4.7 N) and in Polident Overnight (14.41 ± 3.6 N). These cleansing solutions also had a significant effect on the percentage of retention lost (F = 3.271, p = 0.032). The loss of retention in attachments soaked in Listerine (29 ± 9%) was significantly lower than attachments soaked in water (53 ± 12%). The loss of retention in attachments soaked in Efferdent was 49 ± 9%; in Polident Overnight, 34 ± 18%; and in NaOCl, 42 ± 11%. There was no significant difference in the percentage of retention loss between water, Efferdent, NaOCl, and Polident Overnight. There was also no significant difference in the percentage of retention loss between Efferdent, NaOCl, Polident Overnight, and Listerine. CONCLUSION NaOCl significantly decreased the retentive value of Locators. Therefore, it should not be routinely recommended for use as a denture cleanser. Listerine significantly increased the retention of the Locator attachments; however, it is premature to recommend Listerine for use as a denture cleanser.

Reconstruction of a maxillectomy patient with an osteocutaneous flap and implant-retained fixed dental prosthesis: A clinical report

This clinical report describes a multidisciplinary approach in the implant rehabilitation of a 53-year-old white male diagnosed with chondrosarcoma. Following a maxillectomy and insertion of a surgical obturator, the patient was unable to adapt physically and psychologically to the removable prosthesis. The patient underwent a microvascular free tissue transfer using an osteocutaneous free fibula flap to reconstruct a right/left infrastructure maxillectomy defect, a soft tissue modification of the skin component using an implant retained stent, and placement of maxillary dental implants to retain a fixed prosthesis. Prosthodontic planning and treatment considerations are discussed.

Modified fluid wax impression for a severely resorbed edentulous mandibular ridge

This article describes a technique for making a definitive impression for highly displaceable residual ridges. The technique is especially applicable for mandibular edentulous ridges. The choice of the impression materials, as well as the design of the impression tray, focuses on preventing distortion of the displaceable residual ridges during impression making. Using an impression tray with an opening, modeling plastic impression compound and impression wax are used to accurately capture the shape of the residual ridge and place pressure onto denture load-bearing areas. Low-viscosity vinyl polysiloxane impression material is then used over the window opening to capture the surface details of the residual ridge without distorting the displaceable tissues. The use of this technique helps in maintaining the contour and capturing the detail of the tissues, as well as in accurately determining the extent of the muccobuccal denture extensions.

The effect of number and distribution of unsplinted maxillary implants on the load transfer in implant-retained maxillary overdentures: An in vitro study

STATEMENT OF PROBLEM There is little information as to how the number and distribution of implants affect the amount of load transmitted to the palate in implant-retained maxillary overdentures. PURPOSE The purpose of this study was to evaluate the effect of the number and distribution of dental implants on the load transmitted to the palate. MATERIAL AND METHODS Eight implant analogues were placed in a replica of an average sized edentulous maxilla corresponding to the position of canines, first and second premolars, and first molars. The anteroposterior distance between the centers of implants in each quadrant was 8 mm. Fifteen denture bases were fabricated to fit the edentulous maxilla analogue. The denture bases were attached to the oral analogue using 6 different configurations of attachments (6 groups): Either no Locator attachments were used (control group), or the 2 most anterior attachments were attached, or 4 implants were engaged with a distance of 8, 16, or 24 mm between the centers of implants on left and right side, and finally, when all 8 attachments were activated. A force-measuring sensor was used to measure the force transmitted to the palate when a static force of 245 N was applied on the occlusal rims of the denture bases. Data (Newtons) were analyzed using 1-way ANOVA and Tukeys HSD test α=.05). RESULTS The mean (SD) amount of force measured on the palate when the overdentures were supported by 4 Locator attachments; [49.84 (26.52) at 8 mm spacing], [24.42 (15.05) at 16 mm spacing], [35.66 (22.94) at 24 mm spacing] was significantly lower than when no attachments [90.98 (20.20), control], or when 2 Locator attachments were used [76.07 (27.63)] (P<.001). When the overdentures were supported by 8 Locator attachments, the force measured on the palate [20.67(16.06) N] was significantly lower than that for the control group (P<.001), overdentures supported by 2 Locator attachments (P<.001), and overdentures supported by 4 Locator attachments when the distance between the anterior and posterior implants was 8 mm P=.006). CONCLUSIONS The distribution of implants had a significant effect on the force measured on the palate of the oral analogue in overdentures retained by Locator attachments. When the distance between the 4 implants was 16 or more mm, the load was not significantly lower than the 8 implant design, suggesting that the palate of a 4 implant-retained overdenture with a distance of 16 mm or more, does not contribute significantly to the load transfer to underlying hard palate in the in vitro analogue evaluated.

Effect of axial wall modification on the retention of cement-retained, implant-supported crowns

STATEMENT OF PROBLEM Compromised angulation of implants may result in abutment preparation that is less than ideal. Compromised abutment preparation may affect the retention of implant-retained crowns. PURPOSE The purpose of this study was to investigate the effect of 5 implant abutment designs on the retention of cement-retained crowns by varying the number and position of the axial walls. MATERIAL AND METHODS Five prefabricated abutments were attached to an implant analog and embedded in an acrylic resin block. The first abutment was left intact without modification. Axial walls were partially removed from the remaining abutments to produce abutments with 3 walls, 2 adjacent walls, 2 opposing walls, and 1 wall. Five crowns were made for each group. The screw access channel for the first abutment was completely filled with composite resin and the rest were partially filled. The retentive surface area of each abutment was calculated. Crowns were cemented with zinc phosphate cement. Tensile force was applied to separate the castings from the abutments. Peak load to dislodgment was recorded. A 1-way ANOVA was used to test for a significant difference followed by the Tukey Honestly Significant Difference test (α=.05). RESULTS The abutment with 2 opposing axial walls had significantly higher retention than that of all other groups (F=149.9, df =24, P<.001). The abutment with 3 walls exhibited the second highest retention and was significantly greater than abutments with 2 adjacent walls, 1, and 4 walls. Abutments with 2 adjacent walls and 1 wall were not significantly different from each other. The unmodified abutment with 4 walls exhibited the lowest retention despite having a large retentive surface area. CONCLUSIONS The retention of cemented crowns on implant abutments is influenced by the number and position of axial walls.

Effect of implant angulation and impression technique on impressions of NobelActive implants

STATEMENT OF PROBLEM How the configuration of the NobelActive internal conical connection affects implant impressions is uncertain. PURPOSE The purpose of this study was to measure the effect in vitro of closed and open tray impression techniques for NobelActive implants placed at various angulations. MATERIAL AND METHODS Six NobelActive implants were placed in a master maxillary cast as follows: 0 degrees of angulation to a line drawn perpendicular to the occlusal plane in the first molar area, 15 degrees of angulation to a line drawn perpendicular to the occlusal plane in the first premolar area, and 30 degrees of angulation to a line drawn perpendicular to the occlusal plane in the lateral incisor area. Twelve open tray and 12 closed tray impressions were made. Occlusal, lateral, and frontal view photographs of the resulting casts were used to measure the linear and angular displacement of implant analogs. Statistical analysis was performed with a factorial analysis of variance (ANOVA), followed by the Tukey HSD test (α=.05). RESULTS No significant difference was found in the impressions made of NobelActive implants with the open or closed tray technique (linear displacement: F=0.93, P=.34; angular displacement: F=2.09, P=.15). In addition, implant angulation (0, 15, or 30 degrees) had no effect on the linear or angular displacement of impressions (linear displacement: F=2.72, P=.07; angular displacement: F=0.86, P=.43). Finally, no significant interaction was found between impression technique and implant angulation on NobelActive implants (F=0.25, P=.77; F=1.60, P=.20). CONCLUSIONS Within the limitations of this study, impression technique (open vs closed tray) and implant angulation (0, 15, and 30 degrees) had no significant effect on in vitro impressions of NobelActive implants.