Walter Bowles

Walter Bowles

Walter Bowles, Ph.D., D.D.S., M.S., B.Pharm

Academic Title

Associate Professor
Division of Endodontics
Department of Restorative Services


Nuclear Pharmacy, Certificate, University of New Mexico, 1979; Endodontics, Certificate, University of Minnesota, 1991
Pharmacy, B.S., University of New Mexico, 1979
M.S., University of Minnesota, 1991
Oral Biology/Neuroscience, Ph.D., University of Minnesota 2009
Doctory of Dental Surgery (DDS), University of Missouri at Kansas City, 1985

Contact Info




Office Address

8-166 Moos Tower
515 Delaware St. SE
Minneapolis, MN 55455

Bio Statement

Dr. Bowles is an Associate Professor, Division of Endodontics, Department of Restorative Sciences in the School of Dentistry, University of Minnesota. He is also a member of the Graduate Faculty in Dentistry, the Dental Research Institute and the Oral Health Clinical Research Center

Dr. Bowles joined the division in 1993 as a research associate after obtaining an Institutional Clinical Scientist award for PhD research. Practice experience was obtained from military training and independent private practice, along with providing part-time clinical instruction at the University of Minnesota. As an assistant professor Dr. Bowles directed the graduate endodontic program until 2000, and is a former director of the division of endodontics, which oversees the graduate and undergraduate endodontic programs.

Dr. Bowles has authored/co-authored over 65 publications in areas of endodontic research, pain and inflammation. He is a member of the University of Minnesota senate, president-elect of the Pharmacology, Toxicology and Therapeutics section of the International Association for Dental Research, member of the Warner Lambert/Edward H. Hatton Awards Committee of the American Association for Dental Research, and on the Scientific Advisory Panel for the Journal of Endodontics.


Institutional Clinical Scientist Award 1993-1996

Travel Award, International Association of Dental Research - Pulp Biology Presentation 1994

Omicron Kappa Upsilon (National Dental Honor Society) 2000

Faculty travel award - American Association of Endodontists 2003 - 2005

Rho Chi Honors (Pharmacy) 1978-1979.

Research Interests

Current research interests include pain and inflammation in human, animal and in vitro models, as well as endodontic evidence-based research.

Evaluation of Tissue Levels of Nerve Growth Factor (NGF) in Periapical Endodontic Lesions Principal investigator. A research pilot study was submitted to the Minnesota Clinical Dental Research Center. This study examined our hypothesis of neurotrophin involvement in chronic inflammation. ($17,000 direct costs).

Tissue Levels of Inflammatory Mediators as Measured by Microdialysis of Dental Pulp Principal investigator. A research pilot study funded by the Minnesota Clinical Dental Research Center ($12,000 direct costs).

Oral Surgery and Initiation of Neurogenic Inflammation Co-Investigator. RO1 grant evaluating the origin of immunoreactive substance P in the surgical wound of humans, and determining the role of endogenous substance P in mediating post-surgical neurogenic inflammation and wound healing. Postsurgical levels of bradykinin, substance P, prostaglandin E2, and LTB4 were evaluated (competitive renewal awarded 1999; $999,194).

Research Diagnostic Criteria: Reliability and Validity -NIH/NIDCR RO1 DE13331-01A1 Co-Inves. Funded 2001 ($2,209,047 direct costs)

Evaluation of Extracellular Neuropeptide Levels in Inflamed Pulp. Co-PI $3800 American Association of Endodontists.

Differences in Neuropeptide Content and Release from Dental Pulp. Co-PI $4800 American Association of Endodontists.

Evaluation of Functional Cannabinoid Receptors in Dental Pulp. Co-PI $3562 American Association of Endodontists.

Assessing Outcomes of TMJ Alloplastic Implants NIDCR RO1. Co-Inv. Comparison of particle characteristics, cellular and neural responses to removed Proplas-teflon and Silastic alloplastic TMJ implants to non-implant TMJ tissues including correlation of clinical characteristics (pain severity, joint dysfunction, imaging changes and rheumatiological disease) Funded 2002 (Direct costs $1,250,000)

Minnesota TMJ Implant Registry and Repository. NIDCR. Co-Investigator. Development of a TMJ registry and repository to conduct intramural research and facilitate extramural research on TMJ implants with the goal of enhancing understanding of the biological and behavioral outcomes of patients with TMJ implants and their improvement. Neurobiological evaluation of the molecular, neurochemical, and neuronal responses of local TMJ tissues to different types of implant materials. Funded 2002 ($5,900,000).

Mechanisms of Opioid Receptor Interactions NIH RO1. Co Inv. ($1,250,000 direct costs - funded 2003-2007)

Effects of Neurotrophins on Peptidergic Neurons in Dental Pulp. PhD thesis project. This research goal is evaluating the effects and mechanisms neurotrophins alter activity of dental pulp peptidergic neurons. Involved areas include examining effects of different neurotrophins, possible mechanisms of action, receptor locations, and dose response curves. Additional areas include development of an animal model of hyperalgesia for use in evaluating neurotrophic effects and methods of intervention.

Imaging Endodontic Infection- Use of radiolabelled compounds to image periapical infection in early stages before lesions can be detected by conventional means (i.e. radiographs). Pilot study.

Neural modulation of defense and healing in the development of periapical lesions- Use of test compounds and neural manipulations (i.e. V2 and V3 transections) to examine the role of neural components in the development of healing. Pilot study.

Clinical instrument grant - Tulsa Dental -awarded 1999 ; $5200.

Equipment grant - ASI Medical Inc. $6315.00, 2004.

Comparison of Initial Non-Surgical Endodontic Treatment and Single-Tooth Implants. Principle investigator, American Association of Endodontists. Direct costs $300,000 (funded July, 2007).

Pathophysiological mechanisms for clinical and research diagnostic criteria in burning mouth. NIH Coinvestigator 10% Direct costs $3,863,994 (Submitted).

An investigational method of instrumenting root canals. 3 M Company. PI $19, 940, 2007.


1. Hargreaves KM, Bowles WR, & Garry MG. An In Vitro Method to Evaluate Regulation of Neuropeptide Release from Dental Pulp. J. Endod. 18(12):597-600, 1992.

2. Hargreaves KM, Roszkowski MT, Jackson DL, Bowles WR, Durnett-Richardson J, Swift JQ. Neuroendocrine and immune responses to injury, degeneration and repair. Proceedings of 1994 NIDR TMD Workshop, 1994.

3. Hargreaves KM, Swift JQ, Roszkowski M, Bowles W, Gary M, & Jackson D. Pharmacology of  Peripheral Neuropeptide and Inflammatory Mediator Release. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod. 78(4): 503-510, 1994.

4. Ulrich YM, Hargreaves KM, Harding-Rose CA, Bowles WR, and Engeland WC. Characterization of iCGRP Release from Adrenal Capsule Primary Afferent Neurons. Endocr. Res. 24(3-4), pp 777-778,  1998.

5. Doroschak AM, Bowles WR, Hargreaves KM. Evaluation of the combination of flurbiprofen and tramadol for management of endodontic pain J. Endod. 25(10): 660-3, 1999. Cover Photo.

6. Lepinski A, Hargreaves KM, Goodis H, Bowles WR. Bradykinin Levels in Dental Pulp by Microdialysis. J. Endod. 26(12): 744-747, 2000.

7. Rhodus NL, Myers S, Bowles W, Schwartz B, and Parsons H. Burning Mouth Syndrome: Diagnosis and Treatment. Northwest Dent. 79(3): 21-28, 2000.

8. Goodis HE, Bowles WR, Hargreaves KM. Prostaglandin E2 Enhances Bradykinin Evoked iCGRP Release in Bovine Dental Pulp. J. Dent. Res. 79(8): 1604-1607, 2000.

9. Ulrich-Lai YM, Harding-Rose CA, Guo A, Bowles WR, and Engeland, WC. ACTH Inhibits the Capsaicin-Evoked Release of CGRP from Rat Adrenal Afferent Nerves. Am. J. of Physiol. Regul. Integr. Comp. Physiol. 280:R137-142, 2001.

10. Wurm C, Richardson JD, Bowles WR, and Hargreaves K. Evaluation of Functional GABAB Receptors in Dental Pulp. J. Endod. 27(10):620-3, 2001.

11. Bowles WR, Withrow J, Lepinski AM, and Hargreaves KM. Tissue levels of immunoreactive substance P are increased in patients with irreversible pulpitis. J. Endod. 29(4):265-7, 2003.

12. Kurtz JR, Perdigao J, Geraldeli S, Hodges JS, Bowles WR. Bond strengths of tooth-colored posts – effect of sealer, dentin adhesive, and root region. Am. J. Dent. 2003;16:31A-36A.

13. Bowles WR, Flores CM, Jackson DL and Hargreaves KM. -Adrenoceptor Regulation of CGRP  Release from Capsaicin-Sensitive Neurons. J. Dent. Res. 82(4):308-11, 2003.

14. Hargreaves KM, Bowles WR, and Jackson DL. Intrinsic Regulation of CGRP Release by Dental Pulp  Sympathetic Fibers. J. Dent. Res. 82(5):398-401, 2003.

15. Hargreaves KM, Jackson DL, and Bowles WR. Adrenergic Regulation of Capsaicin-sensitive Neurons in Dental Pulp. J. Endod. 29(6):397-399, 2003. 

16. Bowles WR, Sabino M, Harding-Rose C, and Hargreaves KM. Nerve growth factor treatment enhances release of immunoreactive calcitonin gene related peptide but not substance P from spinal dorsal horn slices in rats. Neuroscience Ltr 363(3):239-242, 2004.

17. Rhodus, NL, Cheng B, Myers S, Bowles WR, Ho V, Ondrey F. A comparison of the pro- inflammatory NF-dependent cytokines: TNF-, IL1, IL-6 and IL-8 in different oral fluids from oral lichen planus patients. Clin Immunol 114(3): 278-283, 2005.

18. Doyle S, Hodges JS, Pesun I, Law A, Bowles WR. Retrospective Cross Sectional Comparison of Initial Non-Surgical Endodontic Treatment and Single-Tooth Implants. J. Endod 2006; 32(9):822- 827.

19. Rhodus, NL, Bowles, W, Myers, S, Miller, L, Ho, V, and Ondrey, F. Proinflammatory cytokine levels in saliva before and after treatment of (erosive) oral lichen planus (OLP) with dexamethasone. Oral Dis 12(2): 112-6, 2006.

20. Bowles WR, Sabino M, Harding-Rose C, and Hargreaves KM. Chronic Nerve Growth Factor administration Increases the Peripheral Exocytotic Activity of Capsaicin-Sensitive Cutaneous Neurons. Neurosci Lett 403(3): 305-308, 2006.

21. Matwychuk MJ, Bowles WR, McClanahan SB, Hodges JS, and Pesun IJ. Shaping abilities of two different engine driven rotary nickel titanium systems and stainless steel balanced force technique in mandibular molars. J. Endod 33(7):868-71, 2007.

22. Doyle SL, Hodges JS, Pesun IJ, Baisden MK, Bowles WR. Factors affecting outcomes for single-tooth implants and endodontic restorations. J. Endod. 33(4): 399-402, 2006.

23. Doyle SL, Hodges JS, Pesun IJ, Law AS, Bowles WR. Retrospective cross sectional comparison of initial nonsurgical endodontic treatment and single-tooth implants. Compend Contin Educ Dent. 2007;28(6):296-301

24. Anderson GC, Perdigao J, Hodges JS, and Bowles WR. Removal Efficiency and Effectiveness of Fiber Posts Using Three Techniques. Quintessence Int. 2007;38(8):663-70.

25. Attar S, Bowles WR, Baisden MK, Hodges JS, McClanahan SB. Evaluation of pretreatment analgesia and endodontic treatment for postoperative endodontic pain. J Endod. 2008;34(6):652-5.

26. Degerness R, Bowles W. Anatomic determination of the mesiobuccal root resection level in maxillary molars. J Endod. 2008;34(10):1182-6.

27. Ryan JL, Jureidini B, Hodges JS, Baisden M, Swift JQ, Bowles WR. Gender differences in analgesia for endodontic pain. J Endod. 2008 May;34(5):552-6.

28. Zeng P, Roa A, Zhang G, Wiedmann TS, Bowles WR. Solubility Properties of Chlorhexidine Salts. Drug Dev Ind Pharm. 2009;35(2):172-6.

29. Zeng P, Zhang G, Rao A, Bowles W, Wiedmann TS. Concentration dependent aggregation properties of chlorhexidine salts. Int J Pharm. 2009;367(1-2):73-8.

30. Petrino JA, Boda K, Shambarger S, Bowles WR, and McClanahan SB. Challenges in regererative endodontics: a case series. J Endod 36: 536-41, 2010.

31. McCarthy PJ, McClanahan SB, Hodges JS and Bowles WR. Frequency of localization of the painful tooth by patients presenting for an endodontic emergency. J Endod 36:801-5, 2010.

32. Degerness RA and Bowles WR. Dimension, Anatomy and Morphology of the Mesiobuccal Root Canal System in Maxillary Molars. J. Endod 36(6):985-9, 2010.

33. Koivisto T, Ahmad M. and Bowles WR. Evaluation of Inferior Alveolar Nerve Proximity to Teeth Apicies- Effect of Age and Gender. J. Endod 37(3):311-5, 2011.

34. Turner C, Eggleston G, Wiedman T, Johnson N, Bowles WR. Sniffing out endodontic pain-effect of intranasal analgesic on post-endodontic pain. J Endod 37(4): 439-444, 2011.

35. Maillet M, Bowles WR, McClannahan SL, John MT, Ahmad M. Cone Beam Computed Tomography Evaluation of Maxillary Sinusitis. J Endod 2011;37:753-7.

36. McClannahan SL, Baisden MK, Bowles WR. Endodontic Diagnostic Terminology Update. NW Dent. 2011; 90:25-7.

37. Bowles WR, Burke R, Sabino ML, Harding-Rose C, Lunos S, Hargreaves KM. Sex differences in neuropeptide content and release from rat dental pulp. J Endod 2011; 37:1098-101.

38. Ryan J, Bowles WR, Baisden MK, McClannahan SL. Case Report: Mandibular 1st molar with 6 canals. J Endod 2011; 37:878-80.

39. Koivisto T, Bowles WR and Rohrer M. Frequency and distribution of radiolucent jaw lesions: a retrospective analysis of 9,723 cases. J Endod 2012: 38:729-32.

40. Bierma MM, Bowles WR, Baisden MK, McClannahan SL. Heat Testing Methodology Comparison. J Endod 2012; 38:1106-9.

41. Koivisto T, Bowles WR and Rohrer M. Malignant Lymphoma in Maxilla with Cystic Involvement: A Case Report. J Endodo 2013:39(7):935-8.

42. Mestres G, Abdolhosseini M, Bowles WR, Huang SH, Aparicio C, Gorr SU, Ginebra MP. Antimicrobial properties and dentin bonding strength of magnesium phosphate cements for endodontic applications. Acta Biomater. 2013:9(9):8384-93.

43. Boda KK, Bowles WR, McClanahan SB. The effect of P:L ratio and pre-mixing on the sealing properties of Roth 801 sealer. Northwest Dentistry 2013:92(3) 21-5.

44. Harris S, Bowles WR, Fok A,McClanahan S. An Anatomical Investigation of the Mandibular First Molar Using Micro-Computed Tomography. J Endod 2013: 39(11):1374-8.

45. Wiswall A, Bowles WR, McClanahan SB, Harris S. Palatal injections: Comparison of Four Techniques for Injection Acceptability. NW Dent 2014 (accepted).

46. Rodriguez-Figueroa C, McClanahan SB, Bowles WR. Spectorphotmetric Determination of Irrigant Extrusion using Passive Ultrasoni Irrigation, EndoActivator or Syringe Irrigation. J Endod 2014 (in press).

47. Read JK, McClanahan SB, Khan AA, Bowles WR. Effect of Ibuprofen on Masking Endodontic Diagnosis. J Endod 2014 (in press).

Book Chapters

1. Hargreaves K, Roszkowski M, Jackson D, Bowles W, Richardson J & Swift J. Neuroendocrine and Immune Responses to Injury, Degeneration and Repair in Temporomandibular Disorders and Related Pain Conditions by B Sessel, R. Dionne, and P. Bryant (eds), IASP Press, Seattle, WA, pp 273-292, 1995 .

2. Hargreaves KM, Swift JQ, Bunczak-Reeh MA, Buck SJ, Reese K, Roszkowski MT, Bowles WR, and Jackson DL: Pulpal Responses to Inflammation: Implications for Pain Treatment. Dentin Pulp Complex by: Shimoo M, Maeda T, Suda H, Takahashi K (eds). Quintessence International, pp 93-96, 1996.

3. Hargreaves KM, Bowles WR, Roszkowski MT, Jackson DL, Richardson JD, Engelstad M: Regulation of Neuropeptide Secretion from Pulp. Dentin Pulp Complex by: Shimoo, M., Maeda, T., Suda, H.,Takahashi, K. (eds). Quintessence International, pp 188-192, 1996.

4. Bowles WR, Drum MM, Eleazer PD. Endodontic and Implant Algorithms. Dent Clin N. Amer.54(2):401-13, 2010.

5. Curan A, Bowles WR. Orofacial Injury and Reactive Disorders in Principles of General and Head and Neck Pathology 2014 (in press)

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