Garland Hershey - Academia.edu (original) (raw)
Papers by Garland Hershey
Journal of the American Dental Association, Sep 1, 1988
The importance of attractive dental and facial appearance is at an all-time high for the American... more The importance of attractive dental and facial appearance is at an all-time high for the American consumer. Because of this emphasis on appearance, the esthetic impact of the orthodontic appliance is a matter of great concern to prospective patients. This article presents an overview of the esthetic features of currently available orthodontic appliances.
Angle Orthodontist, Jul 1, 2012
To investigate the distribution of distal and lateral forces produced by orthodontic asymmetric h... more To investigate the distribution of distal and lateral forces produced by orthodontic asymmetric headgear (AHG) using mathematical models to assess periodontal ligament (PDL) influence and to attempt to resolve apparent inconsistencies in the literature. Mechanical models for AHG were constructed to calculate AHG force magnitudes and direction using the theory of elasticity. The PDL was simulated by elastic springs attached to the inner-bow terminals of the AHG. The total storage energy (E(t)) of the AHG and the supporting springs was integrated to evaluate the distal and lateral forces produced by minimizing E(t) (Castigliano's theorem). All analytical solutions were derived symbolically. The spring-supported headgear model (SSHG) predicted the magnitude and distribution of distal forces consistent with our data and the published data of others. The SSHG model revealed that the lateral forces delivered to the inner-bow terminals were not equal, and the spring constant (stiffness of the PDL) affected the magnitude and direction of the resultant lateral forces. Changing the stiffness of the PDL…
American Journal of Orthodontics, Mar 1, 1981
The investigation evaluated and compared the effectiveness of five face-bow types in delivering u... more The investigation evaluated and compared the effectiveness of five face-bow types in delivering unilateral distal forces to their inner-bow terminals. The face-bow types evaluated were bilaterally symmetrical, soldered offset, spring attachment, swivel offset, and power arm. A strain-gauge transducer system was used in the laboratory analysis. A theoretical analysis was also conducted, patterned after the method of Haack and Weinstein, and the results were compared to those obtained from the laboratory analysis. The method used for the theoretical evaluation of the sample face-bows was found to be a reliable means of approximating the percentage distribution of distal forces to the inner-bow terminals. The magnitude and direction of the net lateral forces delivered to the inner-bow terminals was also reliably determined. The results of the theoretical and experimental study of the five face-bow types indicate that the power-arm unilateral face-bow and the swivel-offset unilateral face-bow were effective in delivering a clinically significant unilateral distal force. The bilaterally symmetrical face-bow, the soldered-offset unilateral face-bow, and the spring-attachment unilateral face-bow were not effective in delivering clinically significant unilateral distal forces. Every face-bow effective in delivering unilateral distal forces will also deliver a net lateral force to the inner-bow terminals. This net lateral force will have a direction running from the inner-bow terminal receiving the greater distal force toward the terminal receiving the lesser distal force.
PubMed, 1994
Both higher education and the dental profession must seek to develop dentists who can combine tec... more Both higher education and the dental profession must seek to develop dentists who can combine technical competence with sensitivity to ethical and social concerns. Dental education and the overall higher education experience should seek to produce a practitioner who continues to develop as an ethical professional through ongoing learning, experience, and reflection. In pre-professional education, this goal requires integration of disciplinary content with consideration of contemporary issues that often provide the context for clarifying values and ethical behavior. As the knowledge explosion continues to splinter higher education into specialties and subcategories, attention must be given to integrating the campus as a learning community that promotes an interdisciplinary focus on societal issues. Higher education faculty serve as models for students in demonstrating the responsibility to relate one's area of professional expertise to broader ethical and social concerns.
PubMed, Jul 1, 1978
Abstract No Abstract Available. This investigation was supported by NIH research grant number DE ... more Abstract No Abstract Available. This investigation was supported by NIH research grant number DE 02668 from the National Institute of Dental Research and by NIH grant number RR 05333 from the Division of Research Resources.
PubMed, Oct 1, 1976
A series of proprietary zinc phosphate cements were evaluated after mixing on glass slabs at thre... more A series of proprietary zinc phosphate cements were evaluated after mixing on glass slabs at three different temperatures, 23 degrees, 6 degrees and -10 degrees C. Working time, setting time, diametral tensile strength, compressive strength and solubility were investigated. From the results of the tests the following conclusions were made: 1) As the temperature of the mixing slab was decreased, the amount of powder required to maintain a constatnt viscosity increased. 2) Compressive, tensile, and solubility values remained constant as the temperature of the mixing slab was decreased provided a consistent viscosity was maintained. 3) Mixing zinc phosphate cement substantially below the dew point is an acceptable practice provided the powder/liquid ratio is modified accordingly. 4) Although the setting time of zinc phosphate cement generally remained constant at temperatures below 6 degrees C, the working time continued to increase at -10 degrees C. 5) Mixing zinc phosphate cemment on a cold mixing slab increases the working time on the glass slab and decreases the setting time in an oral environment. Both of these alterations are clinically beneficial to the orthodontist.
American Journal of Orthodontics, May 1, 1975
American Journal of Orthodontics and Dentofacial Orthopedics, Sep 1, 2012
Introduction-Our objectives were to develop a reproducible method of superimposing 3dimensional i... more Introduction-Our objectives were to develop a reproducible method of superimposing 3dimensional images for measuring soft-tissue changes over time and to use this method to document changes in lip position after the removal of orthodontic appliances. Methods-Three-dimensional photographs of 50 subjects were made in repose and maximum intercuspation before and after orthodontic appliance removal with a stereo camera. For reliability assessment, 2 photographs were repeated for 15 patients. The images were registered on stable areas, and surface-to-surface measurements were made for defined landmarks. Results-Mean changes were below the level of clinical significance (set at 1.5 mm). However, 51% and 18% of the subjects experienced changes greater than 1.5 mm at the commissures and lower lips, respectively. Conclusions-The use of serial 3-dimensional photographs is a reliable method of documenting soft-tissue changes. Soft-tissue changes after appliance removal are not clinically significant; however, there is great individual variability. Orthodontic tooth or orthopedic bone movement in the face can affect soft-tissue drape; moreover, it is speculated that most fixed orthodontic appliances have a role to play in the soft-tissue drape. Orthodontic treatment decisions with regard to the need for extraction of teeth are often made in midtreatment based on soft-tissue positions. It is important to gain a
American Journal of Orthodontics, Mar 1, 1976
Records consisting of nasal resistance measurements, postero-anterior radiographs, and dental cas... more Records consisting of nasal resistance measurements, postero-anterior radiographs, and dental casts were obtained on seventeen patients before they underwent rapid maxillary expansion. These records were retaken after maximum expansion of the appliance and after 3 months of retention. Measurements of nasal resistance, binasal cavity width, and maxillary first molar width were made for each subject at each stage of treatment. The following conclusions were derived: 1. Rapid maxillary expansion produced a significant reduction in nasal resistance measured at both 0.50 L. per second and 0.25 L. per second air flow. The reduction of nasal resistance by maxillary expansion was stable through a 3-month period of retention. 2. There was very low correlation between the amount of maxillary first molar expansion and change in nasal resistance. Also, changes in nasal resistance showed low correlation with the amount of nasal cavity widening which occurred during the expansion procedure. 3. Changes in nasal cavity width was not closely related to the amount of maxillary first molar expansion. 4. The patient's subjective opinion of changes in his ability to breathe through the nose was not closely related to the amount his nasal resistance was reduced. 5. The change in nasal resistance of subjects who noticed an improvement in their ability to breathe through the nose was not significantly different from nasal resistance change in children who did not notice any change in their breathing. 6. When subjects treated with an all-wire expansion appliance were compared to subjects treated with a wire-and-acrylic appliance, the two groups were not significantly different with respect to maxillary first molar expansion, nasal cavity widening, or changes in nasal resistance. Differences in amount of molar tipping or alveolar bending were not investigated. 7. Patients requiring rapid maxillary expansion treatment for constricted maxillary arches have significantly higher nasal resistance than other orthodontic patients and nonorthodontic subjects. The rapid maxillary expansion procedure reduced the nasal resistance of those treated to a level which was not significantly different from that of subjects with maxillary arches of normal dimensions. 8. The reduction in nasal resistance achieved with the expansion procedure was not lost after 3 months of retention. 9. Where indicated, rapid maxillary expansion is not only an effective method for increasing the width of narrow maxillary arches but also reduces nasal resistance from levels associated with mouth breathing to levels compatible with normal nasal respiration.
American Journal of Orthodontics, Jun 1, 1976
American Journal of Orthodontics, Apr 1, 1975
Journal of Dental Education, Feb 1, 1986
American Journal of Orthodontics, 1972
Journal of Public Health Dentistry, Mar 1, 1981
Journal of the world federation of orthodontists, Dec 1, 2014
Objectives: To re-accomplish a survey of the affiliated organizations of the World Federation of ... more Objectives: To re-accomplish a survey of the affiliated organizations of the World Federation of Orthodontists (WFO) originally surveyed in 1997. Methods: An electronic survey was sent to all affiliated organizations of the WFO addressing specialty recognition, training, practice methods and characteristics of WFO affiliated organizations. Comparisons were made across geographic regions and not individual countries, in accordance with the previous survey. Results: The response rate was 68%. Orthodontics is a well-recognized specialty with generally increasing educational, clinical and organizational standards worldwide. Board certification exists in relatively few countries, with the most commonly-cited reason being lack of demand. Emerging trends in clinical practice including temporary anchorage devices and cone beam computed tomography were widely-utilized. Conclusions: The 1997 survey was the first time a comprehensive evaluation of orthodontics throughout the world was evaluated, and the 2012 study represents the first comparisons to the 1997 data. v TABLE OF CONTENTS LIST OF TABLES.
Academic Medicine, Jun 1, 1990
American Journal of Orthodontics and Dentofacial Orthopedics, Mar 1, 2010
Introduction: Pain is a major concern of patients before orthodontic treatment. Currently, the mo... more Introduction: Pain is a major concern of patients before orthodontic treatment. Currently, the most frequently recommended treatments for pain after archwire placement or appliance adjustment are over-the-counter (OTC) analgesics. Although the overuse of OTC medications and their potential side effects are concerns, particularly for children, no study to date has investigated a nonpharmacologic option for pain management as an alternative for these analgesics. Methods: A parallel 2-group stratified block randomized clinical trial was designed to assess the pain response of adolescents during the first week after initial archwire placement. The subjects were randomly assigned to 1 of 2 pain management groups: bite wafer (BW) or OTC analgesics. Pain levels were reported on a numerical rating scale. The intensity and unpleasantness of the pain were also assessed. Data were collected at 8 times over a 7-day period. A general linear mixed model with heterogeneous compound symmetry covariance matrix was fitted separately for each outcome. Estimates from the mixed model were used to test a noninferiority hypothesis that the BW group, on average, was not inferior with respect to pain management to the OTC group. Results: The patterns of pain level, intensity, and unpleasantness over time were similar for the 2 groups (P .0.33). Pain management for the BW group as indicated by pain level, intensity, and unpleasantness was not inferior to that of the OTC group (P .0.39). Conclusions: In adolescents, the BW is a nonpharmacologic option for pain management after orthodontic procedures that is at least as effective as OTC analgesics.
The Journal of Prosthetic Dentistry, 1985
SEALS AND SCHWARTZ retentive clasps, and reciprocal components. The wax patterns of the restorati... more SEALS AND SCHWARTZ retentive clasps, and reciprocal components. The wax patterns of the restorations should be contoured on a surveyor in harmony with the path of insertion and design of removable partial dentures. Successful integration of fixed and removable prosthodontics is dependent on adequate diagnostic information and perceptive execution of restorative procedures.
American Journal of Orthodontics, May 1, 1974
1. Am J Orthod. 1974 May;65(5):483-502. Soft-tissue profile change associated with surgical corre... more 1. Am J Orthod. 1974 May;65(5):483-502. Soft-tissue profile change associated with surgical correction of the prognathic mandible. Hershey HG, Smith LH. PMID: 4524314 [PubMed - indexed for MEDLINE]. MeSH Terms. Adolescent; ...
Journal of the American Dental Association, Sep 1, 1988
The importance of attractive dental and facial appearance is at an all-time high for the American... more The importance of attractive dental and facial appearance is at an all-time high for the American consumer. Because of this emphasis on appearance, the esthetic impact of the orthodontic appliance is a matter of great concern to prospective patients. This article presents an overview of the esthetic features of currently available orthodontic appliances.
Angle Orthodontist, Jul 1, 2012
To investigate the distribution of distal and lateral forces produced by orthodontic asymmetric h... more To investigate the distribution of distal and lateral forces produced by orthodontic asymmetric headgear (AHG) using mathematical models to assess periodontal ligament (PDL) influence and to attempt to resolve apparent inconsistencies in the literature. Mechanical models for AHG were constructed to calculate AHG force magnitudes and direction using the theory of elasticity. The PDL was simulated by elastic springs attached to the inner-bow terminals of the AHG. The total storage energy (E(t)) of the AHG and the supporting springs was integrated to evaluate the distal and lateral forces produced by minimizing E(t) (Castigliano's theorem). All analytical solutions were derived symbolically. The spring-supported headgear model (SSHG) predicted the magnitude and distribution of distal forces consistent with our data and the published data of others. The SSHG model revealed that the lateral forces delivered to the inner-bow terminals were not equal, and the spring constant (stiffness of the PDL) affected the magnitude and direction of the resultant lateral forces. Changing the stiffness of the PDL…
American Journal of Orthodontics, Mar 1, 1981
The investigation evaluated and compared the effectiveness of five face-bow types in delivering u... more The investigation evaluated and compared the effectiveness of five face-bow types in delivering unilateral distal forces to their inner-bow terminals. The face-bow types evaluated were bilaterally symmetrical, soldered offset, spring attachment, swivel offset, and power arm. A strain-gauge transducer system was used in the laboratory analysis. A theoretical analysis was also conducted, patterned after the method of Haack and Weinstein, and the results were compared to those obtained from the laboratory analysis. The method used for the theoretical evaluation of the sample face-bows was found to be a reliable means of approximating the percentage distribution of distal forces to the inner-bow terminals. The magnitude and direction of the net lateral forces delivered to the inner-bow terminals was also reliably determined. The results of the theoretical and experimental study of the five face-bow types indicate that the power-arm unilateral face-bow and the swivel-offset unilateral face-bow were effective in delivering a clinically significant unilateral distal force. The bilaterally symmetrical face-bow, the soldered-offset unilateral face-bow, and the spring-attachment unilateral face-bow were not effective in delivering clinically significant unilateral distal forces. Every face-bow effective in delivering unilateral distal forces will also deliver a net lateral force to the inner-bow terminals. This net lateral force will have a direction running from the inner-bow terminal receiving the greater distal force toward the terminal receiving the lesser distal force.
PubMed, 1994
Both higher education and the dental profession must seek to develop dentists who can combine tec... more Both higher education and the dental profession must seek to develop dentists who can combine technical competence with sensitivity to ethical and social concerns. Dental education and the overall higher education experience should seek to produce a practitioner who continues to develop as an ethical professional through ongoing learning, experience, and reflection. In pre-professional education, this goal requires integration of disciplinary content with consideration of contemporary issues that often provide the context for clarifying values and ethical behavior. As the knowledge explosion continues to splinter higher education into specialties and subcategories, attention must be given to integrating the campus as a learning community that promotes an interdisciplinary focus on societal issues. Higher education faculty serve as models for students in demonstrating the responsibility to relate one's area of professional expertise to broader ethical and social concerns.
PubMed, Jul 1, 1978
Abstract No Abstract Available. This investigation was supported by NIH research grant number DE ... more Abstract No Abstract Available. This investigation was supported by NIH research grant number DE 02668 from the National Institute of Dental Research and by NIH grant number RR 05333 from the Division of Research Resources.
PubMed, Oct 1, 1976
A series of proprietary zinc phosphate cements were evaluated after mixing on glass slabs at thre... more A series of proprietary zinc phosphate cements were evaluated after mixing on glass slabs at three different temperatures, 23 degrees, 6 degrees and -10 degrees C. Working time, setting time, diametral tensile strength, compressive strength and solubility were investigated. From the results of the tests the following conclusions were made: 1) As the temperature of the mixing slab was decreased, the amount of powder required to maintain a constatnt viscosity increased. 2) Compressive, tensile, and solubility values remained constant as the temperature of the mixing slab was decreased provided a consistent viscosity was maintained. 3) Mixing zinc phosphate cement substantially below the dew point is an acceptable practice provided the powder/liquid ratio is modified accordingly. 4) Although the setting time of zinc phosphate cement generally remained constant at temperatures below 6 degrees C, the working time continued to increase at -10 degrees C. 5) Mixing zinc phosphate cemment on a cold mixing slab increases the working time on the glass slab and decreases the setting time in an oral environment. Both of these alterations are clinically beneficial to the orthodontist.
American Journal of Orthodontics, May 1, 1975
American Journal of Orthodontics and Dentofacial Orthopedics, Sep 1, 2012
Introduction-Our objectives were to develop a reproducible method of superimposing 3dimensional i... more Introduction-Our objectives were to develop a reproducible method of superimposing 3dimensional images for measuring soft-tissue changes over time and to use this method to document changes in lip position after the removal of orthodontic appliances. Methods-Three-dimensional photographs of 50 subjects were made in repose and maximum intercuspation before and after orthodontic appliance removal with a stereo camera. For reliability assessment, 2 photographs were repeated for 15 patients. The images were registered on stable areas, and surface-to-surface measurements were made for defined landmarks. Results-Mean changes were below the level of clinical significance (set at 1.5 mm). However, 51% and 18% of the subjects experienced changes greater than 1.5 mm at the commissures and lower lips, respectively. Conclusions-The use of serial 3-dimensional photographs is a reliable method of documenting soft-tissue changes. Soft-tissue changes after appliance removal are not clinically significant; however, there is great individual variability. Orthodontic tooth or orthopedic bone movement in the face can affect soft-tissue drape; moreover, it is speculated that most fixed orthodontic appliances have a role to play in the soft-tissue drape. Orthodontic treatment decisions with regard to the need for extraction of teeth are often made in midtreatment based on soft-tissue positions. It is important to gain a
American Journal of Orthodontics, Mar 1, 1976
Records consisting of nasal resistance measurements, postero-anterior radiographs, and dental cas... more Records consisting of nasal resistance measurements, postero-anterior radiographs, and dental casts were obtained on seventeen patients before they underwent rapid maxillary expansion. These records were retaken after maximum expansion of the appliance and after 3 months of retention. Measurements of nasal resistance, binasal cavity width, and maxillary first molar width were made for each subject at each stage of treatment. The following conclusions were derived: 1. Rapid maxillary expansion produced a significant reduction in nasal resistance measured at both 0.50 L. per second and 0.25 L. per second air flow. The reduction of nasal resistance by maxillary expansion was stable through a 3-month period of retention. 2. There was very low correlation between the amount of maxillary first molar expansion and change in nasal resistance. Also, changes in nasal resistance showed low correlation with the amount of nasal cavity widening which occurred during the expansion procedure. 3. Changes in nasal cavity width was not closely related to the amount of maxillary first molar expansion. 4. The patient's subjective opinion of changes in his ability to breathe through the nose was not closely related to the amount his nasal resistance was reduced. 5. The change in nasal resistance of subjects who noticed an improvement in their ability to breathe through the nose was not significantly different from nasal resistance change in children who did not notice any change in their breathing. 6. When subjects treated with an all-wire expansion appliance were compared to subjects treated with a wire-and-acrylic appliance, the two groups were not significantly different with respect to maxillary first molar expansion, nasal cavity widening, or changes in nasal resistance. Differences in amount of molar tipping or alveolar bending were not investigated. 7. Patients requiring rapid maxillary expansion treatment for constricted maxillary arches have significantly higher nasal resistance than other orthodontic patients and nonorthodontic subjects. The rapid maxillary expansion procedure reduced the nasal resistance of those treated to a level which was not significantly different from that of subjects with maxillary arches of normal dimensions. 8. The reduction in nasal resistance achieved with the expansion procedure was not lost after 3 months of retention. 9. Where indicated, rapid maxillary expansion is not only an effective method for increasing the width of narrow maxillary arches but also reduces nasal resistance from levels associated with mouth breathing to levels compatible with normal nasal respiration.
American Journal of Orthodontics, Jun 1, 1976
American Journal of Orthodontics, Apr 1, 1975
Journal of Dental Education, Feb 1, 1986
American Journal of Orthodontics, 1972
Journal of Public Health Dentistry, Mar 1, 1981
Journal of the world federation of orthodontists, Dec 1, 2014
Objectives: To re-accomplish a survey of the affiliated organizations of the World Federation of ... more Objectives: To re-accomplish a survey of the affiliated organizations of the World Federation of Orthodontists (WFO) originally surveyed in 1997. Methods: An electronic survey was sent to all affiliated organizations of the WFO addressing specialty recognition, training, practice methods and characteristics of WFO affiliated organizations. Comparisons were made across geographic regions and not individual countries, in accordance with the previous survey. Results: The response rate was 68%. Orthodontics is a well-recognized specialty with generally increasing educational, clinical and organizational standards worldwide. Board certification exists in relatively few countries, with the most commonly-cited reason being lack of demand. Emerging trends in clinical practice including temporary anchorage devices and cone beam computed tomography were widely-utilized. Conclusions: The 1997 survey was the first time a comprehensive evaluation of orthodontics throughout the world was evaluated, and the 2012 study represents the first comparisons to the 1997 data. v TABLE OF CONTENTS LIST OF TABLES.
Academic Medicine, Jun 1, 1990
American Journal of Orthodontics and Dentofacial Orthopedics, Mar 1, 2010
Introduction: Pain is a major concern of patients before orthodontic treatment. Currently, the mo... more Introduction: Pain is a major concern of patients before orthodontic treatment. Currently, the most frequently recommended treatments for pain after archwire placement or appliance adjustment are over-the-counter (OTC) analgesics. Although the overuse of OTC medications and their potential side effects are concerns, particularly for children, no study to date has investigated a nonpharmacologic option for pain management as an alternative for these analgesics. Methods: A parallel 2-group stratified block randomized clinical trial was designed to assess the pain response of adolescents during the first week after initial archwire placement. The subjects were randomly assigned to 1 of 2 pain management groups: bite wafer (BW) or OTC analgesics. Pain levels were reported on a numerical rating scale. The intensity and unpleasantness of the pain were also assessed. Data were collected at 8 times over a 7-day period. A general linear mixed model with heterogeneous compound symmetry covariance matrix was fitted separately for each outcome. Estimates from the mixed model were used to test a noninferiority hypothesis that the BW group, on average, was not inferior with respect to pain management to the OTC group. Results: The patterns of pain level, intensity, and unpleasantness over time were similar for the 2 groups (P .0.33). Pain management for the BW group as indicated by pain level, intensity, and unpleasantness was not inferior to that of the OTC group (P .0.39). Conclusions: In adolescents, the BW is a nonpharmacologic option for pain management after orthodontic procedures that is at least as effective as OTC analgesics.
The Journal of Prosthetic Dentistry, 1985
SEALS AND SCHWARTZ retentive clasps, and reciprocal components. The wax patterns of the restorati... more SEALS AND SCHWARTZ retentive clasps, and reciprocal components. The wax patterns of the restorations should be contoured on a surveyor in harmony with the path of insertion and design of removable partial dentures. Successful integration of fixed and removable prosthodontics is dependent on adequate diagnostic information and perceptive execution of restorative procedures.
American Journal of Orthodontics, May 1, 1974
1. Am J Orthod. 1974 May;65(5):483-502. Soft-tissue profile change associated with surgical corre... more 1. Am J Orthod. 1974 May;65(5):483-502. Soft-tissue profile change associated with surgical correction of the prognathic mandible. Hershey HG, Smith LH. PMID: 4524314 [PubMed - indexed for MEDLINE]. MeSH Terms. Adolescent; ...