Sex Differences in the Hemoglobin Oxygenation State of the Resting Healthy Human Masseter Muscle

Aims: To determine whether sex differences exist in tissue oxygen saturation (StO2) and the hemoglobin (Hb) oxygenationstate of the resting human masseter muscle. Methods: Near-infrared spectroscopy (NIRS) was used to measure StO2 and Hb oxygenation state in 20 healthy adult volunteers (10 women and 10 men). To determine the measurement range and reliability of the NIRS recording probe, the probe was set up on 12 layers of white acrylic resin plate, each 3 mm thick. Total hemoglobin levels were measured while a red vinyl resin plate, 1 mm thick, was inserted in turn between each of the 12 layers. Distances from the skin surface to the lateral surface (S-L) and to the medial surface (S-M) of the right masseter at the middle portion of the masseter were measured on T1-weighted magnetic resonance images (repetition time 500 ms, echo time 23 ms). Thickness of the masseter was calculatedby subtraction [(S-M) – (S-L)]. For the study of Hb oxygenation state, the probe was positioned at the same position on the skin surface at the mandibular postural (rest) position. Results: The measurement range of the NIRS probe was from 9 to 21 mm under the skin, and the reliability of the probe was judged by intra- and inter-class correlation coefficients. There was no sex difference in S-L and the thickness of the masseter; the means of S-L and masseter thickness were 9.3 mm and 15.5 mm in men and 9.8 mm and 14.3 mm in women, respectively. Except for StO2 values, there were significant sex differences in the Hb oxygenation parameters, with the mean values in the men being approximately twice those in the women. Conclusion: These results provide evidence that a sex difference in the Hb oxygenation state may exist in the masseter muscle of normal healthy subjects.

hemoglobin oxygenation; hemodynamics; blood flow; masseter muscle

1. Maksud MG. Conditioning for sports. In: Ryan AJ and Alleman FL Jr (eds). Sports Medicine, ed 2. San Diego: Academic Press, 1989:85–112.

2. Harris DV. Special considerations for the female athlete. In: Grana WA, Kalenak A (eds). Clinical Sports Medicine. Philadelphia: Saunders, 1991:66–69.

3. Rhoades R, Pflanzer R. Human Physiology. Philadelphia: Saunders College Publications, 1989:514–548.

4. Cook JP, Creager MA, Osmundson PJ, Shepherd JT. Sex differences in control of cutaneous blood flow. Circulation 1990;82:1607–1615.

5. Ganong WF. Gas transport between the lungs and the tissues. In: Review of Medical Physiology, ed 19. Stamford, CT: Appleton & Lange, 1999:635–639.

6. Kossion AE, Karkazis HC. The influence of gender on the masseter electromyographic jaw-jerk reflex in young human subjects. J Oral Rehabil 1994;21:419–430.

7. The Academy of Prosthodontics. The glossary of prosthodontic terms, ed 7. J Prosthet Dent 1999;81: 39–110.

8. Narita N, Tominaga T, Koshu K, Mizoi K, Yoshimoto T. Monitoring of brain tissue haemoglobin concentration and oxygen saturation using a three-wavelength spectrophotometric method. Neurol Res 1994;16:428–432.

9. Fricton JR, Kroening RJ, Hathaway KM. TMJ and Craniofacial Pain: Diagnosis and Management, ed 1. St Louis: Ishiyaku EuroAmerica, 1989:53–65.

10. SPSS Inc, Marketing Department. SPSS Base 8.0 Application Guide. Chicago: SPSS, 1998:37–62.

11. Fleiss JL. The Design and Analysis of Clinical Experiments. New York: John Wiley & Sons, 1986:1–32.

12. Fleiss JL, Slakter MJ, Fischman SL, Park MH, Chilton NW. Inter-examiner reliability in caries trials. J Dent Res 1979;58:604–609.

13. Shrout PE, Fleiss JL. Intraclass correlation: Uses in assessing rater reliability. Psychol Bull 1979;86:420–428.

14. Delcanho RT, Kim YJ, Clark GT. Haemodynamic changes induced by submaximal isometric contraction in painful and non-painful human masseter using near-infrared spectroscopy. Arch Oral Biol 1996;41:585–596.

15. Mancini DM, Bolinger L, Li H, Kendrick K, Chance B, Wilson JR. Validation of near-infrared spectroscopy in humans. J Appl Physiol 1994;77:2740–2747.

16. Hazeki O, Tamura M. Quantitative analysis of hemoglobin oxygenation state of rat brain in situ by nearinfrared spectrophotometry. J Appl Physiol 1988;64: 796–802.

17. Chance B, Nioka S, Kent J, et al. Time-resolved spectroscopy of hemoglobin and myoglobin in resting and ischemic muscle. Anal Biochem 1998;174:698–707.

18. Raaddsheer MC, Kiliaridis S, Van Eijden TMGJ, Van Ginkel FC, Prahl-Andersen B. Masseter muscle thickness in grouping individuals and its relation to facial morphology. Arch Oral Biol 1996;41:323–332.

19. Jensen MD, Nguyen TT, Mijares H, Johnson CM, Murray MJ. Effects of gender on resting leg blood flow: Implications for measurement of regional substrate oxidation. Am Physiol Soc 1998;84:141–145.

20. Wascher TC, Bammer R, Stollberger R, Bahadori B, Wallner S, Toplak H. Forearm composition contributes to differences in reactive hyperaemia between healthy men and women. Eur J Clin Invest 1998;28:243–248.

21. Stal P, Ericksson P-O, Thornell L-E. Differences in capillary supply between human oro-facial, masticatory and limb muscle. J Muscle Res Cell Motil 1996;17:183–197.

22. Miller AJ. Craniomandibular Muscles: Their Role in Function and Form. London: CRC Press, 1991:12–43.

23. Maxwell LC, Carlsson DS, McNamara JA Jr, Faulkner JA. Histochemical characteristics of the masseter and temporalis muscles of the rhesus monkey (Macaca mulatta). Anat Rec 1979;193:389–402.

24. Miller AJ, Farias M. Histochemical and electromyographic analysis of craniomandibular muscles in the rhesus monkey, Macaca mulatta. J Oral Maxillofac Surg 1988;46:767–776.