IU Indianapolis ScholarWorks :: Browsing by Author "Hennon, David K."

Browsing by Author "Hennon, David K."

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Apert Syndrome : A Descriptive Analysis of Selected Computed Tomographic Images of the Craniofacial Complex
(1988) Schafer, Alan Boulware; Garner, LaForrest D.; Bixler, David; Hennon, David K.; Kasle, Myron J.; Miller, James R.; Shanks, James C.
The purpose of this study was to demonstrate how selected computed tomographic images of the craniofacial complex may be used in a descriptive evaluation of cranial dysmorphology in living subjects with Apert syndrome. Computed tomographic images using coronal sections through the optic disc, planum sphenoidale, and axial sections through petrous ridges, pterygopalatine fossa, and midorbital level from two Apert syndrome and two non-syndrome controls were evaluated. Reference lines were established using actual and constructed landmarks. The results were tabulated for all four subjects. The two Apert subjects (in contrast to the non-syndrome subjects) demonstrated the following: a) orbital proptosis with a reduced bony orbital depth and elongation of the orbits in a superior direction with an altered vertical orbital axis b) increased lateral orbital wall angle c) alteration of the anterior cranial base with depression of the ethmoid complex d) midface regression Interestingly, ocular hypertelorism, which has been reported to be a feature of Apert syndrome, could not be confirmed by use of these CT scans. The findings obtained from this study are consistent with the published characteristics of Apert syndrome. In conclusion, this study demonstrates the utility of computed tomographic images in the evaluation of craniofacial dysmorphology.
A Clinical Study Evaluating a Mandibular Repositioning Appliance to Treat Obstructive Sleep Apnea
(1992) Coghlan, J. Kevin; Roberts, W. Eugene; Beiswanger, Bradley B.; Shanks, James C.; Garner, LaForrest D.; Hennon, David K.; Nelson, Charles L.
The study evaluated the effects of a mandibular repositioning appliance (MRA) in patients with obstructive sleep apnea. The MRA was designed to hold the mandible anteriorly in an attempt to maintain a patent airway. Eleven subjects completed a full-night polysomnogram wherein their normal sleep was recorded half the night without the appliance (control) and the other half with the appliance (test). The sequencing of test and control halves was randomly assigned to avoid bias. After seven subjects were tested with the MRA, the MRA was modified for four additional patients by placing anterior vertical elastics (MRA*) to minimize the opening of the mandible. The skeletal and soft tissue changes with both appliances were analyzed using lateral cephalometric radiographs. The MRA was found to have no significant effect on the obstructive sleep apnea patients as a group. Individual response to the appliance varied from noticeably worse to marked improvement. Subject #2A exhibited the reduction of a moderate-to-severe apnea (Apnea-hypopnea index 55.92) to a clinically acceptable level (Apnea-hypopnea index 9.57) with appliance wear. The treatment was considered successful. Significant cephalometric changes with appliance wear were increased lower facial height, a superiorly positioned hyoid bone relative to the mandibular plane, and a decreased posterior airway space. No cephalometric measurement could accurately predict the outcome of the treatment, and posterior airway space, commonly measured in sleep research, was not reliable. The mandibular repositioning appliance was effective in treating a small percentage of individuals with obstructive sleep apnea. A polysomnogram was needed to quantitatively measure the effectiveness of treatment. Under no circumstance should a subjective evaluation by the patient or the clinician be used to assess treatment results. Further investigation is required to evaluate the long-term effectiveness of this treatment. Periodic follow-up sleep studies are required for any patient treated with this appliance until more long term studies are completed.
Comparative Tensile Strengths of Brackets Bonded to Porcelain with Orthodontic Adhesives and Porcelain Repair Systems
(1986) Eustaquio, Robert I.; Garner, LaForrest D.; Barton, Paul; Hennon, David K.; Moore, B. Keith; Muñoz, Carlos; Shanks, James C.
This study evaluated the feasibility of bonding brackets to porcelain for orthodontic purposes by measuring and comparing tensile strengths of five silane-based adhesive systems. Each adhesive system bonded mesh pad brackets to 10 glazed and 10 deglazed metal-ceramic crowns and the specimens were then thermocycled between 16 degrees and 56 degrees for 2500 cycles. Clinically relevant bond strengths, comparable to those of adhesives bonding brackets to enamel, were recorded for four of the systems compared. System l+ and Porcelain Primer had the highest mean values followed by Lee's Enamelite 500, then Vivadent's Silanit, Contact-Resin and Isopast, then 3M's Concise and Scotchprime. Most, if not all, failure sites for the four were at the bracket-resin interface. Two-way factorial analysis of variance demonstrated significant differences at P<.001 among the four adhesives but no contribution of surface effect, whether glazed or deglazed, was suggested statistically. Neuman-Keul sequential range tests showed significant differences between System l+ and the three other systems but no significant differences among the three were detected. Den-Mat's Ultrabond recorded extremely low tensile strength values and was of dubious clinical value. A t-test suggested that deglazing porcelain contributed no significant difference in strength compared with intact, glazed porcelain. All failure sites were at the porcelain-resin interface for this product. Since resin may remain bonded to porcelain following debonding, George Taub's diamond polishing paste and Shofu porcelain polishing wheels were compared as to their ability in restoring the porcelain to its original state. Because of the great adhesive bond of the resin to porcelain, craters, pits or tears may be created when resin is cleaned from porcelain with conventional scalers and pliers. The diamond paste gave a better restorative finish than the stones but the end result depended on the extent of original damage following cleaning. Orthodontists should take this point into account when considering bonding to porcelain crowns or veneers for esthetics sake where final risks may outweigh initial benefits. In a limited survey of 100 orthodontists responding to a questionnaire, 89% indicated that they have bonded or contemplated bonding to composite restored teeth, and 83% indicated that they have bonded or contemplated bonding to porcelain.
A Comparison Study of Temporomandibular Joint Symptoms in Patients Following Mandibular Advancement by Bilateral Sagittal Split Osteotomies: Rigid Fixation Versus Nonrigid Fixation
(1989) Flynn, Brent Cameron; Roberts, W. Eugene; Brown, David T.; Nelson, Charles L.; Shanks, James C.; Hennon, David K.
Primary consideration must be given to the temporomandibular joint when planning and performing orthognathic surgical procedures. It has long been understood that the status of the temporomandibular joint can easily and unintentionally be altered during orthognathic surgery, regardless of the method of fixation used. With the advent of modern fixation techniques, many clinicians and investigators have questioned the effects of rigid fixation on the temporomandibular joint. To investigate this, a clinical study of 40 patients treated with mandibular advancement for retrognathism was performed. Twenty patients were treated with rigid fixation while another 20 patients had inferior border wires placed with anterior skeletal fixation. All patients were asked questions regarding the history of their temporomandibular joints. In addition, all patients received a clinical postoperative temporomandibular joints. In addition, all patients received a clinical postoperative temporomandibular joint evaluation. The results were statistically analyzed with the Chi-square analysis and Standard T test. It was determined that the Null Hypothesis could not be rejected for any of the symptoms evaluated in this study. The results support the belief that rigid fixation is no different when compared to wire osteosynthesis in terms of prevalence of temporomandibular joint symptoms.
Evaluation of the Tensile Bond Strength of Orthodontic Bracket Bases Using Glass Ionomer Cement as an Adhesive
(1992) Burns, Richard D., Jr.; Roberts, W. Eugene, Jr.; Garetto, Lawrence P.; Moore, B. Keith; Miller, James R.; Shanks, James C., Jr.; Hennon, David K.
The search for an orthodontic bonding adhesive that has chemical adhesion to enamel and releases fluoride into the oral environment has led to experimentation with glass ionomer cements. This study compared the tensile bond strength of eight different orthodontic bracket base designs in vitro and assessed the amount of adhesive remaining on the bracket pad after debonding. Each bracket base design included in this study had unique characteristics warranting their inclusion. The groups contained brackets with 60, 80, and 100 gauge mesh pads; 100 gauge mesh sandblasted pads; perforated metal bases; Micro-Lock™ photo-etched bases; Dyna-Lock™ integral bracket/bases; and ceramic silane-coated bracket pads. Groups contained 20 to 22 specimens that were bonded to bovine incisor teeth embedded in a self-curing acrylic block that could be held in the testing machine. Pre-encapsulated glass ionomer cement (Ketac-Fil™) was the experimental adhesive. The adhesive was mixed according to the manufacturer's instructions in a dental amalgamator. The specimens were thermocycled between water oaths of 15°C and 55°C. The specimens spent 30 seconds in each bath for a total of 2,500 cycles and were stored in a humidor until debonding. After 14 days, the specimens were subjected to a tensile force using an Instron mechanical testing machine until failure occurred. The Micro-Loc™ photo-etched base had significantly higher mean tensile bond strength (p<0.05) than all other brackets tested. The ceramic brackets were unable to be tested due to the extremely weak bond strength which did not allow preparation of the samples for debonding. Following debonding, the percentage of adhesive remaining attached to the bracket base was determined using a grid in the ocular of a light microscope. In general, the site of bond failure involved the base/adhesive interface. The Dyna-Lock™ integral bracket/base and 80 gauge mesh base had a greater mean percent of adhesive remaining attached to the base. (Dyna-Lock™ 45 percent and 80 gauge mesh 43 percent vs. all other < 20 percent.) The results indicate that the bracket base design can influence the bond strength when GIC is used as an orthodontic adhesive and suggests that development of GIC with increased fracture toughness might increase bond strength.
Long Term Maxillary Growth Following Primary Bone Grafting in Unilateral Cleft Lip and Palate
(1996) Gandelsman, Genrikh; Hathaway, Ronald R.; Arbuckle, Gordon R.; Hennon, David K.; Katona, Thomas R.; Shanks, James C.
The question of growth attenuation of the maxillary complex arises in connection with primary osteoplasty procedure. The deficiencies associated with the development of the jaws in unilateral complete cleft lip and palate (UCLP) children is an ongoing problem in terms of growth inhibition and orthodontic treatment. Retardation of growth can be attributed to intrinsic cleft factors and/or associated with the treatment of the cleft condition. In this study, the extent of such deficiency, if any, was investigated by assessing arch length, arch width, arch symmetry and inter-arch harmony. Seventeen orthodontic casts of UCLP children (mean age 7 years 11 months) were obtained. All were treated with a primary osteoplasty at James Whitcomb Riley Hospital for Children at Indianapolis, Indiana. The sample was compared to an age and sex matched non-cleft control group (n=38). None of the subjects had undergone orthodontic treatment beyond infant maxillary orthopedics. Anatomic landmarks were identified and digitized by means of optical electronics. The data were automatically fed into a computer which executed preprogrammed data manipulation algorithms. Significant (p<0.05) inhibition of growth has taken place in the maxillary arches of the UCLP group in both anteroposterior and transverse directions. lntercanine width (ICW) was reduced on average by 7.6 mm (23.6 percent) while the intermolar width (IMW) was shortened by 3.9 mm (7.8 percent). Sagittal growth was retarded by 5.5 mm (17.4 percent). A gradient of "normalization" originating at a point of surgical insult was observed anteroposteriorly in the transverse maxillary dimension. In the mandible, ICW was retarded by 2.0 mm (7.8 percent) while IMW and A-P growth vectors were not significantly affected. This investigation also revealed significant (p = 0.0001) differences in the size of the maxillary anterior palatal area (cleft mean = 83.5 mm2, non-cleft mean = 133.9 mm2). These findings lead to the conclusion that primary osteoplasty may contribute to maxillary growth attenuation with concomitant mandibular compensatory growth patterns.
Reducing Frictional Resistance between Orthodontic Bracket and Arch Wire
(1986) Souweine, Leon E., Jr.; Garner, LaForrest D.; Barton, Paul; Hennon, David K.; Lund, Melvin R.; Shanks, James C.
This investigation evaluated a proposed clinical method for decreasing frictional resistance between an orthodontic bracket and an archwire during usage of the continuous edgewise method of space closure. It was hypothesized that altering the leading edge of the bracket (in the direction of retraction) would significantly decrease the force required to retract a bracket along an archwire at several angulations. Fifteen medium twin brackets with .018 inch slots from three manufacturers were tested on an Instron testing machine, and the force needed to overcome binding friction at five angulations on an .016 inch wire was recorded and submitted for statistical analysis. In addition, the edge of each bracket was partially immersed into the electrolytic solution of the Esmadent bracket and band reconditioner and reduced for one minute. These brackets were then retested twice: once with the reduced edge leading and once with the reduced edge rotated 180° so that it was trailing. There was a statistically significant difference between manufacturers as well as between procedures. The reduced leading bracket edge resulted in the greatest decrease in friction. These differences were significant at the p<.01 level. The advantage of reducing only one edge of the bracket instead of both, is that the unaltered wing allows maximum slot engagement with the larger wires normally utilized during finishing. This study provided a rationale as well as a procedure for the clinician to selectively alter aspects of stock bracket configuration to meet the needs of decreased friction as well as total control.
Tensile Bond Strength of Light-Activated Composite for Bonding Metal and Ceramic Brackets
(1989) Shepherd, Jeffrey Dean; Roberts, W. Eugene; Moore, B. Keith; Shanks, James C.; Hennon, David K.; Nelson, Charles L.
Visible light-activated composite adhesives offer several advantages over conventional autopolymerizing adhesives such as extended working time, immediate ligation and easier cleanup. This study compared in vitro tensile bond strength and site of failure of a new light-activated adhesive and a commonly used two-paste adhesive for bonding ceramic and metal brackets. Manufacturer recommended light-activation times were evaluated using hardness as an indicator of cure. Light-activated composite specimens 0.3 mm in thickness were cured beneath metal brackets for 30 seconds and ceramic brackets for 10 seconds. Knoop hardness values were determined at various time intervals over a seven-day period. An evaluation of the hardness testing data indicated that manufacturer recommended cure times for both brackets were adequate. A significant increase in hardness over time also was noted for all specimens. Mean tensile bond strength comparisons were determined by dividing 88 human maxillary premolars into four groups of 22 specimens each. Each group had either metal or ceramic brackets bonded with either two-paste or light-activated adhesive. After bonding, specimens were thermocycled and stored in a humidor set at 37°C for seven days. Ceramic bracket specimens underwent further preparation to decrease bracket failures during debonding. At the end of seven days specimens were subjected to tensile stress using an Instron mechanical testing machine until failure occurred. No significant differences in tensile bond strength were found between light-activated and two-paste adhesives when similar brackets were used. Ceramic brackets bonded with either adhesive had significantly higher bond strengths than metal brackets bonded with the same adhesive. Nineteen ceramic brackets failed during debonding; however, tensile bond strengths of these specimens were not significantly different from those specimens where adhesive failure occurred. Specimens were viewed by light microscopy to determine percent bond failure at enamel surface. Groups using ceramic brackets tended to have a higher percent bond failure at enamel surface than did metal bracket groups. High bond strengths demonstrated by ceramic brackets coupled with the brittleness of the bracket itself requires special attention during debonding to avoid enamel damage. Early light-cured adhesives were not practical due to slow setting times plus their inability to cure beneath metal brackets. The adhesive tested in this study appears to have overcome these problems when manufacturer's recommended cure times are used.
Tensile Bond Strength of Light-Activated Glass Ionomer for Bonding Metal and Ceramic Brackets
(1990) Wentz, Todd Zane; Roberts, W. Eugene; Moore, B. Keith; Shanks, James C.; Hennon, David K.; Garetto, Lawrence P.; Simmons, Kirt E.
Visible light-activated glass ionomer offers several advantages over conventional autopolymerizing adhesives, such as extended control of working time, immediate ligation, fluoride release, and a chemical bond to enamel. This study compared in vitro tensile bond strength of a new light-activated glass ionomer with that of a chemically-cured glass ionomer for bonding ceramic and metal orthodontic brackets. The manufacturer's recommended light-activation time of 30 seconds was evaluated by Knoop hardness testing. Specimens cured for 30 and 60 seconds were evaluated with Knoop hardness testing at various time intervals over a 24-hour period. An evaluation of the data indicated that the manufacturer's recommended cure time was adequate. Human maxillary premolars were divided into six groups of 20. Each group was bonded with either light-activated glass ionomer or a chemically-cured glass ionomer utilizing either metal or ceramic brackets. After bonding, specimens were thermocycled and stored in water at 37°C for 14 days. After the 14-day storage period specimens were tested in the tensile mode of an lnstron testing machine until failure. Ceramic brackets were found to have a significantly greater mean tensile bond strength than metal brackets when light-activated glass ionomer was used as the bonding agent. Mean tensile bond strength of metal brackets bonded with light-activated glass ionomer were significantly greater than metal brackets bonded with a chemically-cured glass ionomer. Ceramic brackets had a negligible bond strength when bonded with a chemically-cured glass ionomer. The light-activated glass ionomer tested in this study appears to have an adequate in vitro mean tensile bond strength to be considered for an orthodontic bonding adhesive.
The Influence of Etching Times and Fluoride Acid Gels on the Bonding of Orthodontic Brackets
(1988) Hoagburg, Steven Joseph; Garner, LaForrest D.; Shanks, James C., Jr.; Moore, B. Keith; Nelson, Charles L.; Hennon, David K.
This study evaluated the influence of etching times and the addition of fluoride to a phosphoric acid gel on the tensile bond strength of orthodontic brackets bonded to human enamel using a 40% phosphoric acid gel containing no fluoride, 0.44% sodium fluoride and 0.8% stannous fluoride. The percent cohesive failure after debonding was also studied. In addition, the enamel surface was evaluated for reaction products and etching morphology by scanning electron microscopy. Such a reduction in etching times and the addition of fluorides into the etchants should result in less damage to the tooth and a decrease in enamel decalcification. For the tensile bond strength part of the study, 189 noncarious and nonrestored human premolar teeth were divided into three groups corresponding to the three different etching gels. Each group was subdivided into three other groups which consisted of the three etching times, 15, 30 and 60 seconds. There were a total of 21 samples in each of the nine groups. After etching with the appropriate gels and etching times, brackets were bonded to the buccal surfaces of the teeth with Concise orthodontic resin. The samples were thermocycled and stored in 37°C until testing. Seven days after bonding, the samples were tested in tension in an Instron testing machine. After debonding, the percent cohesive failure was evaluated under the microscope at 40X. All groups were compared using the two way analysis of variance. There was no significant difference in tensile bond strength between the three etchants. However, etching with the NaF etchant for 15 seconds produced significantly different results from the other NaF groups. However, there was no significant difference related to etching times for the other two etchants. The highest tensile bond strength (71.7 ± 2 3.0 kg/cm2 ) was recorded with the H3PO4 gel when etched for 60 seconds and the lowest tensile bond strength (48.9 ± 13.6 kg/cm2) was recorded with the NaF etchant when etched for 15 seconds. There was no significant difference in the percent cohesive failure between the three etchants. There was a significant difference in the NaF group when the etching times were changed. Etching with the NaF group for 15 seconds showed a significant difference when compared with the other NaF groups. However, the other two etchants showed no significant difference between the different etching times. Cohesive failure for all groups occurred mainly at the mesh-resin interface. The highest percent cohesive failure (95.7 ± 14.8%) occurred in the SnF2 group when etched for 30 seconds. The lowest percent cohesive failure (70.9 ± 40.6%) occurred in the NaF group when etched for 15 seconds. In the second part of this study nine human maxillary premolar teeth were etched with the three different gels at the three time intervals and were evaluated under the SEM at magnifications of 1500X and 5000X for reaction products and etching morphology. Fluorides incorporated into the etching gels should reduce enamel decalcification, and decreasing the etching times also reduces enamel loss. Results of the present study suggest that incorporating of these fluorides in the etchants, along with decreasing the etching times, warrants clinical evaluation.

Browsing by Author "Hennon, David K."

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