Mastication is a complex process that involves activities of the facial muscles, the elevator and suprahyoidal muscles, and the tongue. These activities result in patterns of rhythmic mandibular movements, food manipulation, and the crushing of food between the teeth. Saliva facilitates mastication by moistening food particles, making a bolus, and assisting swallowing, whereas food consistency modifies masticatory forces, the mandibular jaw movements, the duration of the mastication cycle, and the number of cycles preceding the first swallow. Jaw elevator EMG activity research shows a clear relation between muscular activity and food properties. The teeth, masticatory muscles, and temporomandibular joints are also important because together they form the mechanism by which the food particles are fragmented. Hard and dry foods require more chewing cycles and a longer time in the mouth until swallowing for sufficient breakdown to take place and for enough saliva to be added to form a coherent bolus safe enough for swallowing. Product characteristics, the amount of saliva, dentition, and bite force affect the chewing performance. This study presents an update and synopsis of the effects of saliva, food, dentition, muscle force, and temporomandibular disorders on the masticatory process. © 2006 Taylor & Francis.644193201Hiiemae, K.M., Thexton, A.J., Crompton, A.W., Intra-oral food transport: The fundamental mechanism of feeding (1978) Muscle Adaptation in the Craniofacial Region, pp. 181-208. , Carlson DS, McNamara JA, editors. Ann Arbor, Michigan: University of MichiganPedersen, A.M., Bardow, A., Jensen, S.B., Nauntofte, B., Saliva and gastrointestinal functions of taste, mastication, swallowing and digestion (2002) Oral Dis, 8, pp. 117-129Nishinari, K., Introduction to a special issue of JTS (2004) J Texture Stud, 35, pp. ix-xiLund, J.P., Mastication and its control by the brain stem (1991) Crit Rev Oral Biol Med, 2, pp. 33-64Ottenhoff, F.M., Van Der Bilt, A., Van Der Glas, H.W., Bosman, F., Peripherally induced and anticipated elevator muscle activity during simulated chewing in humans (1992) J Neurophysiol, 67, pp. 75-83Hutchings, J.B., Lillford, P.J., The perception of food texture: The philosophy of the breakdown path (1988) J Texture Stud, 19, pp. 103-115Prinz, J.F., Lucas, P.W., Swallow thresholds in human mastication (1995) Arch Oral Biol, 40, pp. 401-403Prinz, J.F., Lucas, P.W., An optimization model for mastication and swallowing in mammals (1997) Proc R Soc Lond B, 264, pp. 1715-1721Anderson, D.J., Hector, M.P., Linden, R.W.A., The effects of unilateral and bilateral chewing, empty clenching and simulated bruxism, on the masticatory-parotid salivary reflex in man (1996) Exp Physiol, 81, pp. 305-312Scott, B.J.J., Bajaj, J., Linden, R.W.A., The contribution of mechanoreceptive neurones in the gingival tissues to the masticatory-parotid salivary reflex in man (1999) J Oral Rehabil, 26, pp. 791-797Dodds, M.W.J., Johnson, D.A., Yeh, C.K., Health benefits of saliva: A review (2005) J Dent, 33, pp. 223-233Johnson, D.A., Sreebny, L.M., Effect of increased mastication on the secretory process of the rat parotid gland (1973) Arch Oral Biol, 18, pp. 1555-1557Yeh, C.K., Johnson, D.A., Dodds, M.W.J., Sakai, S., Rugh, J.D., Hatch, J.P., Association of salivary flow rates with maximal bite force (2000) J Dent Res, 79, pp. 1560-1565Wilding, R.C., The association between chewing efficiency and occlusal contact area in man (1993) Arch Oral Biol, 38, pp. 589-596Van Der Bilt, A., Olthoff, L.W., Bosman, F., Oosterhaven, S.P., Chewing performance before and after rehabilitation of postcanine teeth in man (1994) J Dent Res, 73, pp. 1677-1683Julien, K.C., Buschang, P.H., Throckmorton, G.S., Dechow, P.C., Normal masticatory performance in young adults and children (1996) Arch Oral Biol, 41, pp. 69-75Hatch, J.P., Shinkai, R.S.A., Sakai, S., Rugh, J.D., Paunovich, E.D., Determinants of masticatory performance in dentate adults (2000) Arch Oral Biol, 46, pp. 641-648Van Der Bilt, A., Human oral function. A review (2002) Braz J Oral Sci, 1, pp. 7-18Fontijn-Tekamp, F.A., Slagter, A.P., Van Der Bilt, A., Van't Hof, M.A., Witter, D.J., Kalk, W., Biting and chewing in overdentures, full dentures, and natural dentitions (2000) J Dent Res, 79, pp. 1519-1524Peroz, I., Tai, S., Masticatory performance in patients with anterior disk displacement without reduction in comparison with symptom-free volunteers (2001) Eur J Oral Sci, 110, pp. 341-344Kurita, H., Ohtsuka, A., Kurashina, K., Kopp, S., Chewing ability as a parameter for evaluating the disability of patients with temporomandibular disorders (2001) J Oral Rehabil, 28, pp. 463-465Bourne, M.C., Relation between texture and mastication (2004) J Texture Stud, 35, pp. 125-143German, R.Z., Crompton, A.W., Thexton, A.J., The role of animal models in understanding feeding behavior in infants (2004) Int J Orofacial Myology, 30, pp. 20-30Hiiemae, K.M., Mechanisms of food reduction, transport and deglutition: How the texture of food affects feeding behavior (2004) J Texture Stud, 35, pp. 171-200Helkimo, E., Carlsson, G.E., Helkimo, M., Chewing efficiency and state of dentition. A methodologic study (1978) Acta Odontol Scand, 36, pp. 33-41Feldman, R.S., Kapur, K.K., Alman, J.E., Chauncey, H.H., Aging and mastication: Changes in performance and in the swallowing threshold with natural dentition (1980) J Am Geriatr Soc, 28, pp. 97-103Luke, D.A., Lucas, P.W., Chewing efficiency in relation to occlusal and other variations in the natural human dentition (1985) Br Dent J, 159, pp. 401-403Omar, S.M., McEwen, J.D., Ogston, S.A., A test for occlusal function. the value of a masticatory efficiency test in the assessment of occlusal function (1987) Br J Orthod, 14, pp. 85-90Van Der Bilt, A., Olthoff, L.W., Bosman, F., Oosterhaven, S.P., The effect of missing postcanine teeth on chewing performance in man (1993) Arch Oral Biol, 38, pp. 423-429Helkimo, E., Carlsson, G.E., Helkimo, M., Bite force and state of dentition (1977) Acta Odontol Scand, 35, pp. 297-303Slagter, A.P., Bosman, F., Van Der Bilt, A., Comminution of two artificial test foods by dentate and edentulous subjects (1993) J Oral Rehabil, 20, pp. 159-176Geertman, M.E., Slagter, A.P., Van Waas, M.A.J., Kalk, W., Comminution of food with mandibular implant-retained overdentures (1994) J Dent Res, 73, pp. 1858-1864Kapur, K.K., Garrett, N.R., Hamada, M.O., Roumanas, E.D., Freymiller, E., Han, T., A randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part I: Methodology and clinical outcomes (1998) J Prosthet Dent, 79, pp. 555-569Tang, L., Lund, J.P., Taché, R., Clokie, C.M.L., Feine, J.S., A within-subject comparison of mandibular long-bar and hybrid implant-supported prostheses: Evaluation of masticatory function (1999) J Dent Res, 78, pp. 1544-1553Van Kampen, F.M.C., Van Der Bilt, A., Cune, M.S., Fontijn-Tekamp, F.A., Bosman, F., Masticatory function with implant-supported overdentures (2004) J Dent Res, 83, pp. 708-711Agerberg, G., Carlsson, G.E., Chewing ability in relation to dental and general health. Analyses of data obtained from a questionnaire (1981) Acta Odontol Scand, 39, pp. 147-153Wayler, A.H., Chauncey, H.H., Impact of complete dentures and impaired natural dentition on masticatory performance and food choice in healthy aging men (1983) J Prosthet Dent, 49, pp. 427-433Chauncey, H.H., Muench, M.E., Kapur, K.K., Wayler, A.H., The effect of the loss of teeth on diet and nutrition (1984) Int Dent J, 34, pp. 98-104Oosterhaven, S.P., Westert, G.P., Schaub, R.H., Van Der Bilt, A., Social and psychologic implications of missing teeth for chewing ability (1988) Community Dent Oral Epidemiol, 16, pp. 79-82Witter, D.J., Cramwinckel, A.B., Rossum, G.M., Käyser, A.F., Shortened dental arches and masticatory ability (1990) J Dent, 18, pp. 185-189Dellow, P.G., Lund, J.P., Evidence for central timing of rhythmical mastication (1971) J Physiol, 215, pp. 1-13Lund, J.P., Evidence for a central neural pattern generator regulating the chewing cycle (1976) Mastication, pp. 204-212. , Bristol: John Wright and SonsNozaki, S., Iriki, A., Nakamura, Y., Localization of central rhythm generator involved in cortically induced rhythmical masticatory jaw-opening movement in the guinea-pig (1986) J Neurophysiol, 55, pp. 806-825Goldberg, L.J., Chandler, S.H., Central mechanisms of rhythmic trigeminal activity (1990) Neurophysiology of the Jaws and Teeth, pp. 268-293. , Taylor A, editor. Hong Kong: The Macmillan Press LtdMorimoto, T., Inoue, T., Masuda, Y., Nagashima, T., Sensory components facilitating jaw-closing muscle activities in the rabbit (1989) Exp Brain Res, 76, pp. 424-440Yamada, Y., Haraguchi, N., Reflex changes in the masticatory muscles with load perturbations during chewing hard and soft food (1995) Brain Res, 669, pp. 86-92Yamada, Y., Yamamura, K., Possible factors which may affect phase durations in the natural chewing rhythm (1996) Brain Res, 706, pp. 237-242Nakamura, Y., Katakura, N., Generation of masticatory rhythm in the brainstem (1995) Neuroscience Research, 23, pp. 1-19Plesh, O., Bishop, B., McCall, W.D., Effect of gum hardness on chewing pattern (1986) Exp Neurol, 92, pp. 502-512Luschei, E.S., Goldberg, L.J., Neural mechanisms of mandibular control: Mastication and voluntary biting (1981) Handbook of Physiology. Motor Control, 2, pp. 1237-1274. , Brooks VB, editor. Washington DC: American Physiological SocietyHiiemae, K.M., Heath, M.R., Heath, G., Kazazoglu, E., Murray, J., Sapper, D., Natural bites, food consistency and feeding behaviour in man (1996) Arch Oral Biol, 41, pp. 175-189Van Der Bilt, A., Weijnen, F.G., Ottenhoff, F.M., Van Der Glas, H.W., Bosman, F., The role of sensory information in the control of rhythmic open-close movements in humans (1995) J Dent Res, 74, pp. 1658-1664Tabak, L.A., Levine, M.J., Mandel, I.D., Ellison, S.A., Role of salivary mucins in the protection of the oral cavity (1982) J Oral Pathology, 11, pp. 1-17Levine, M.J., Aguirre, A., Hatton, M.N., Tabak, L.A., Artificial salivas: Present and future (1987) J Dent Res, 66, pp. 693-698Van Der Reijden, W.A., Veerman, E.C.I., Van Nieuw Amerongen, A.V., Shear rate dependent viscoelastic behavior of human glandular salivas (1993) Biorheology, 30, pp. 141-152Pangborn, R.M., Lundgren, B., Salivary secretion in response to mastication of crisp bread (1977) J Texture Stud, 8, pp. 463-472Richardson, C.T., Feldman, M., Salivary response to food in humans and its effect on gastric acid secretion (1986) Am J Physiol, 250, pp. G85-91Dawes, C., Physiological factors affecting salivary flow rate, oral sugar clearance, and the sensation of dry mouth in man (1987) J Dent Res, 66, pp. 648-653Watanabe, S., Dawes, C., A comparison of the effects of tasting and chewing foods on the flow rate of whole saliva in man (1988) Arch Oral Biol, 33, pp. 761-764Watanabe, S., Dawes, C., The effects of different foods and concentrations of citric acid on the flow rate of whole saliva in man (1988) Arch Oral Biol, 33, pp. 1-5Mackie, D.A., Pangborn, R.M., Mastication and its influence on human salivary flow and alpha-amylase secretion (1990) Physiol Behav, 47, pp. 593-595Hector, M.P., Linden, R.W.A., Reflexes of salivary secretion (1999) Neural Mechanisms of Salivary Gland Secretion, 1st Edn., pp. 196-217. , Garrett JR, Ekström J, Anderson LC, editors. Basel: KargerLagerlöf, F., Dawes, C., The volume of saliva in the mouth before and after swallowing (1984) J Dent Res, 63, pp. 618-621Liedberg, B., Owall, B., Masticatory ability in experimentally induced xerostomia (1991) Dysphagia, 6, pp. 211-213Anderson, D.J., Hector, M.P., Linden, R.W.A., The possible relation between mastication and parotid secretion in the rabbit (1985) J Physiol, 364, pp. 19-29Mioche, L., Bourdiol, P., Monier, S., Chewing behaviour and bolus formation during mastication of meat with different textures (2003) Arch Oral Biol, 48, pp. 193-200Ferguson, D.B., Botchway, C.A., Circadian variations in flow rate and composition of human stimulated submandibular saliva (1979) Arch Oral Biol, 24, pp. 433-437Flink, H., Tegelberg, A., Lagerlöf, F., Influence of the time of measurement of unstimulated human whole saliva on the diagnosis of hyposalivation (2005) Arch Oral Biol, 50, pp. 553-559Christensen, C.M., Navazesh, M., Brightman, V.J., Effects of pharmacologic reductions in salivary flow on taste thresholds in man (1984) Arch Oral Biol, 29, pp. 17-23Galili, D., Maller, O., Brightman, V.J., The effects of desalivation by duct ligation or salivary gland extirpation on taste preference in rats (1981) Arch Oral Biol, 26, pp. 853-858Christensen, C.M., Role of saliva in human taste perception (1985) Clinical Measurements of Taste and Smell, pp. 414-428. , Meiselman HL, Rivlin RS, editors. New York: MacmillanGuinard, J.-X., Zoumars-Morse, C., Walchak, C., Relation between parotid saliva flow and composition and the perception of gustatory and trigeminal stimuli in foods (1998) Physiol Behav, 63, pp. 109-118Engelen, L., De Wijk, R.A., Prinz, J.F., Van Der Bilt, A., Bosman, F., The relation between saliva flow after different stimulations and the perception of flavor and texture attributes in custard desserts (2003) Physiol Behav, 78, pp. 165-169Engelen, L., De Wijk, R.A., Prinz, J.F., Janssen, A.M., Van Der Bilt, A., Weenen, H., A comparison of the effects of added saliva, α-amylase and water on texture perception in semisolids (2003) Physiol Behav, 78, pp. 805-811Pereira, L.J., Gavião, M.B.D., Van Der Bilt, A., Effects of added fluids on swallowing threshold and chewing process (2005) J Dent Res, , Proc IADR-CED:153Christensen, C.M., Food texture perception (1984) Adv Food Res, 29, pp. 159-199Mioche, L., Bourdiol, P., Martin, J.-F., Noël, Y., Variations in human masseter and temporalis muscle activity related to food texture during free and side-imposed mastication (1999) Arch Oral Biol, 44, pp. 1005-1012Mathevon, E., Mioche, L., Brown, W.E., Culioli, J., Texture analysis of beef cooked at various temperatures by mechanical measurements, sensory assessments and electromyography (1995) J Texture Stud, 26, pp. 175-192Agrawal, K.R., Lucas, P.W., Bruce, I.C., Prinz, J.F., Food properties that influence neuromuscular activity during human mastication (1998) J Dent Res, 77, pp. 1931-1938Bosman, F., Van Der Bilt, A., Van Der Glas, H.W., The taste of chewing (1998) Food Science and Technology Cost 96, pp. 113-120. , Schieberle P, editorNeyraud, E., Peyron, M.A., Vieira, C., Dransfield, E., Influence of bitter taste on mastication pattern (2005) J Dent Res, 84, pp. 250-254Brown, W.E., Langley, K.R., Martin, A., MacFie, H.H., Characterisation of patterns of chewing behaviour in human subjects and their influence on texture perception (1994) J Texture Stud, 25, pp. 455-468Bishop, B., Plesh, O., McCall, W.D., Effects of chewing frequency and bolus hardness on human incisor trajectory and masseter muscle activity (1990) Arch Oral Biol, 35, pp. 311-318Thexton, A.J., Hiiemae, K.M., Crompton, A.W., Food consistency and bite size as regulators of jaw movement during feeding in the cat (1980) J Neurophysiol, 44, pp. 456-474Gavião, M.B.D., Engelen, L., Van Der Bilt, A., Chewing behavior and salivary secretion (2004) Eur J Oral Sci, 112, pp. 19-24Engelen, L., Fontijn-Tekamp, F.A., Van Der Bilt, A., The influence of product and oral characteristics on swallowing (2005) Arch Oral Biol, 50, pp. 739-746Brudevold, F., Kashket, S., Kent, R.L., The effect of sucrose and fat in cookies on salivation and oral retention in humans (1990) J Dent Res, 69, pp. 1278-1282Dawes, C., Dong, C., The flow rate and electrolyte composition of whole saliva elicited by the use of sucrose-containing and sugar-free chewing-gums (1995) Arch Oral Biol, 40, pp. 699-705Palmer, J.B., Rudin, N.J., Lara, G., Crompton, A.W., Coordination of mastication and swallowing (1992) Dysphagia, 7, pp. 187-200Fontijn-Tekamp, F.A., Slagter, A.P., Van Der Bilt, A., Van't Hof, M.A., Kalk, W., Jansen, J.A., Swallowing thresholds of mandibular implant-retained overdentures with variable portion sizes (2004) Clin Oral Impl Res, 15, pp. 375-380Lucas, P.W., Luke, D.A., Is food particle size a criterion for the initiation of swallowing? (1986) J Oral Rehabil, 13, pp. 127-136Fontijn-Tekamp, F.A., Van Der Bilt, A., Abbink, J.H., Bosman, F., Swallowing threshold and masticatory performance in dentate adults (2004) Physiol Behav, 83, pp. 431-436Akeel, R., Nilner, M., Nilner, K., Masticatory efficiency in individuals with natural dentition (1992) Swed Dent J, 16, pp. 191-198Carlsson, G.E., Masticatory efficiency: The effect of age, the loss of teeth and prosthetic rehabilitation (1984) Int Dent J, 34, pp. 93-97Käyser, A.F., Shortened dental arches and oral function (1981) J Oral Rehabil, 8, pp. 457-462Abel, L.F., Manly, R.S., Masticatory function of partial denture patients among navy personnel (1953) J Prosthet Dent, 3, pp. 382-392Yurkstas, A.A., The masticatory act. A review (1965) J Prosthet Dent, 15, pp. 248-260Van Den Braber, W., Van Der Glas, H.W., Van Der Bilt, A., Bosman, F., Masticatory function in retrognathic patients, before and after mandibular advancement surgery (2004) J Oral Maxillofac Surg, 62, pp. 549-554Van Der Bilt, A., Weijnen, F.G., Bosman, F., Van Der Glas, H.W., Kuks, J.B.M., Controlled study of EMG activity of the jaw closers and openers during mastication in patients with myasthenia gravis (2001) Eur J Oral Sci, 109, pp. 160-164Van Kampen, F.M.C., Van Der Bilt, A., Cune, M.S., Bosman, F., The influence of various attachment types in mandibular implant-retained overdentures on maximum bite force and EMG (2002) J Dent Res, 81, pp. 170-173Weijnen, F.G., Van Der Bilt, A., Wokke, J.H.J., Kuks, J.B.M., Van Der Glas, H.W., Bosman, F., Maximal bite force and surface EMG in patients with myasthenia gravis (2000) Muscle Nerve, 23, pp. 1694-1699Boerrigter, E.M., Geertman, M.E., Van Oort, R.P., Bouma, J., Raghoebar, G.M., Van Waas, M.A.J., Patient satisfaction with implant-retained mandibular overdentures. A comparison with new complete dentures not retained by implants: A multicentre randomized clinical trial (1995) Br J Oral Max Surg, 33, pp. 282-288Geertman, M.E., Boerrigter, E.M., Van't Hof, M.A., Van Waas, M.A.J., Van Oort, R.P., Boering, G., Two-center clinical trial of implant-retained mandibular overdentures versus complete dentures: Chewing ability (1996) Community Dent Oral Epidemiol, 24, pp. 79-84Geertman, M.E., Van Waas, M.A.J., Van't Hof, M.A., Kalk, W., Denture satisfaction in a comparative study of implant-retained mandibular overdentures: A randomized clinical trial (1996) Int J Oral Maxillofac Implants, 11, pp. 194-200Lindquist, L.W., Carlsson, G.E., Long-term effects on chewing with mandibular fixed prostheses on osseo-integrated implants (1985) Acta Odontol Scand, 43, pp. 39-45Meijer, H.J.A., Raghoebar, G.M., Van't Hof, M.A., Geertman, M.E., Van Oort, R.P., Implant-retained mandibular overdentures compared with complete denturesa 5-years' follow-up of clinical aspects and patient satisfaction (1999) Clin Oral Impl Res, 10, pp. 238-244Cune, M.S., Van Kampen, F.M.C., Van Der Bilt, A., Bosman, R., Patient satisfaction and preference with magnet, bar-clip, and ball-socket retained mandibular implant overdentures: A cross-over clinical trial (2005) Int J Prosthodont, 18, pp. 99-105Yap, A.U., Chua, E.K., Hoe, J.K., Clinical TMD, pain-related disability and psychological status of TMD patients (2002) J Oral Rehabil, 29, pp. 374-380De Leeuw, R., Boering, G., Stegenga, B., De Bont, L.G.M., Clinical signs of TMJ osteoarthrosis and internal derangement 30 years after nonsurgical treatment (1994) J Orofac Pain, 8, pp. 18-24Sato, S., Nasu, F., Motegi, K., Natural course of nonreducing disc displacement of the temporomandibular joint: Changes in chewing movement and masticatory efficiency (2002) J Oral Maxillofac Surg, 60, pp. 867-872Henrikson, T., Ekberg, E.C., Nilner, M., Masticatory efficiency and ability in relation to occlusion and mandibular dysfunction in girls (1998) Int J Prosthod, 11, pp. 125-132Stegenga, B., Broekhuijsen, M.L., De Bont, L.G.M., Van Willigen, J.D., Bite-force endurance in patients with temporomandibular joint osteoarthrosis and internal derangement (1992) J Oral Rehabil, 19, pp. 639-647Tzakis, M.G., Dahlström, L., Haraldson, T., Evaluation of masticatory function before and after treatment in patients with craniomandibular disorders (1992) J Craniomandib Disord, 6, pp. 267-271Ahlberg, J.P., Kovero, O.A., Hurmerinta, K.A., Zepa, I., Nissinen, M.J., Kononen, M.H., Maximal bite force and its association with signs and symptoms of TMD, occlusion, and body mass index in a cohort of young adults (2003) Cranio, 21, pp. 248-252Bonjardim, L.R., Gavião, M.B.D., Pereira, L.J., Castelo, P.M., Bite force determination in adolescents with and without temporomandibular dysfunction (2005) J Oral Rehabil, 32, pp. 577-583