Orofacial Pain

Our research group focuses on increasing our knowledge concerning the mechanisms behind chronic orofacial pain, emphasizing jaw muscle pain and its sex differences.

Our research is translational, spanning from basic research conducted in patients and matched pain-free controls via human experimental studies where pain is induced experimentally, to clinical intervention studies. We study potential peripheral biomarkers, such as serotonin, glutamate, cytokines and neuropeptides. In collaboration with other research groups we investigate if certain genetic variants (single nucleotide peptides) are associated with jaw muscle pain and study the protein expression patterns in saliva to search for potential unknown pain biomarkers. Adopted methods include intramuscular micro-dialysis, microbiopsies, cold pressor test, exercise-induced analgesia and quantitative sensory testing (sensory and pain thresholds for warmth, cold and mechanical stimuli), as well as genomics and proteomics.

The Orofacial Pain research group is part of the larger Orofacial Neuroscience Group at the Department of Dental Medicine, which in turn collaborates with other leading research groups in Malmö and Aarhus, via the Scandinavian Center for Orofacial Neuroscience (SCON). The group also has a close collaboration with the Specialist Clinic for Orofacial Pain at the Eastman Institute in Stockholm.

Group members

  • Malin Ernberg, DDS, PhD, professor
  • Nikolaos Christidis, DDS, PhD, associate professor
  • Britt Hedenberg-Magnusson, DDS, PhD, associate professor
  • Sofia Louca Jounger, DDS, PhD, lecturer
  • Hajer Jasim, DDS, PhD student
  • Golnaz Barjandi, DDS, PhD student
  • Maria Erkapers, DDS, PhD student


  • Martin Schalling, Eva Kosek, Monica Lövgren, Indre Ljungar, Sophie Erhardt, George Belibasakis, KI
  • Jochen Schwenk, Royal Institute of Technology (KTH), Stockholm
  • Erik Lindfors, Uppsala University
  • Thomas List, Per Alstergren, Malmö University
  • Kaisa Mannerkorpi, University of Gothenburg
  • Björn Gerdle, Bijar Ghafouri, Andreas Dawson, Linköping University
  • Peter Svensson, Lene Baad-Hansen, Eduardo Castrillon, Fernando Exposto, Aarhus University
  • Brian Cairns, University of British Columbia, Vancouver, Canada
  • Taro Arima, University of Sapporo, Japan
  • Akiko Shimada, Osaka University, Japan

Project: Pain genes and muscle biomarkers in TMD myalgia

Here, we use micro-dialysis to investigate the role of serotonin (5-HT) and other algogenic inflammatory markers as well as genetic biomarkers in the pathophysiology underlying temporomandibular disorders (TMD) myalgia in clinical and experimental studies.

Close-up of patient with a thin tube that goes into his cheek and another one that goes out of the cheek.
Intramuscular micro-dialysis of the masseter. This is a method developed by us that allows the collection of different substances from the extracellular environment in-vivo. Photo: Sofia Louca.

We have previously shown that muscle level of 5-HT is elevated in patients with chronic myalgia and correlated to muscle pain and tenderness. 5-HT participates in pain mediation via the 5-HT3 receptor is suggested to be involved both in central and peripheral processing of pain as well as in inflammation. Blocking of the 5-HT3 receptor reduces experimental and clinical pain, but with a large inter-individual variation in the efficacy. We hypothesize that this might be due to genetic factors. Thus, the role of genes coding for the 5-HT3 receptor for pain mediation and efficacy of 5-HT3 antagonists in chronic myalgia is explored.

PhD: Sofia Louca Jounger

Collaborations:  Professor Thomas List, Malmö University, Sweden. Professor Martin Schalling, KI, Associate Professor Nikolaos Christidis, KI, and Professor Peter Svensson, KI, Stockholm, Sweden.

Financial support: Swedish Research Council, Region Stockholm/KI (ALF and SOF), Swedish Dental Association, Swedish Rheumatism Association.

Project: Molecular biomarkers in saliva in health and pain states

Result from a test with the titles "Saliva from healthy subject" and "Saliva from TMD"

The overall aim is to investigate if saliva can be used to sample potential molecular biomarkers for TMD pain.

Peripheral release of algogenic and inflammatory substances is increased in patients with chronic myalgia and headache, including migraine. Saliva contains an extensive collection of potential biomarkers that could play important roles for the pathophysiology of orofacial pain. However, it is often neglected as a body fluid of diagnostic value, even though it is generally well accepted by the patients. In this project saliva levels of 5-HT, glutamate, nerve growth factor (NGF), substance P (SP), calcitonin gene-related peptide (CGRP) and brain derived neurotrophic factor (BDNF) as well as the whole proteome will be compared between patients with TMD myalgia and healthy controls.

PhD: Hajer Jasim

MSci: Victor Madariaga Rivera

Collaboration: Associate Professor Bijar Ghafouri, Linköping University, Sweden; Associate Professor Jochen Schwenk, Royal Institute of Technology, Stockholm, Sweden; Associate Professor Britt Hedenberg-Magnusson, Eastman Institute, Stockholm, Sweden.  

Financial support: Stockholm Community Council (SOF grant), Swedish Dental Association, Swedish Rheumatism Association.

Project: The role of the kynurenine pathway and oral microbiota in chronic muscle pain

The aim of this project is to explore if a shift in the tryptophan metabolism and salivary microbiome participates in the pathogenesis of chronic musculoskeletal pain.

There are indications that chronic stress may cause chronic inflammation and activate the immune system and that this may be associated with pathological changes in the tryptophan metabolism towards the kynurenine pathway. Altered levels of kynurenine metabolites are associated with some chronic pains, psychiatric and gastrointestinal disorders, but to date, there are no published data on the role of the kynurenine pathway in TMD myalgia or fibromyalgia. Further, under pathological conditions the gut microbiota may have a role in tryptophan degradation along the kynurenine pathway both in the periphery and the CNS. If the microbiome composition is altered in chronic myalgia patients is unknown.

PhD student: Golnaz Barjandi

Collaboration: Professor Eva Kosek (co.supervisor),  KI, Professor Sophie Erhardt, KI (co.supervisor), Professor Georgios Belibasakis, KI (co.supervisor), and Associate Professor Britt Hedenberg-Magnusson, Eastman Institute, Stockholm, Sweden (co-supervisor).  

Financial support: Karolinska Institutet (CSTP grant), Stockholm Community Council (ALF).

Project: Jaw motor control in patients with severe tooth wear

The project aims to investigate different aspects of jaw motor control, jaw function and oral health impact on quality of life in patients with severe tooth wear before and after comprehensive oral rehabilitation.

Tooth wear caused by attrition (physical repeated contact between teeth caused by grinding) has been suggested to be a clinical sign of bruxism. Extensive wear may become an aesthetic problem, with short and fragile teeth. Major wear may also cause hypersensitivity and pain in the teeth. Extensive toothwear often requires a comprehensive prosthetic rehabilitation but influences from a prosthetic intervention concerning parafunction, temporomandibular symptoms, and oral health impact on quality of life is unclear and is desirable to clarify. This can be done with novel technologies.

PhD student: Maria Erkapers

Collaborations: Professor Peter Svensson (co-supervisor), Aarhus University, PhD Susanna Segerström, Uppsala University (co-supervisor).  

Financial support: Region Uppsala.

Research support

  • Region Stockholm/KI – SOF
  • Clinical Scientist Training Program KI (Golnaz Barjandi).
  • The Swedish Rheumatism Association.
  • Swedish Dental Association