Sareh Said Yekta

Publications of Sareh Said Yekta

• Verification of nerve integrity after surgical intervention using quantitative sensory testing.

  Authors: Sareh Said-Yekta, Ralf Smeets, Marcella Esteves-Oliveira, Jamal M Stein, Dieter Riediger, Friedrich Lampert

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 07/2011; 70(2):263-71.

  The aim of this study was to apply a standardized Quantitative Sensory Testing (QST) approach in patients to investigate whether oral surgery can lead to sensory changes, even if the patients do notThe aim of this study was to apply a standardized Quantitative Sensory Testing (QST) approach in patients to investigate whether oral surgery can lead to sensory changes, even if the patients do not report any sensory disturbances. Furthermore, this study determines the degree and duration of possible neuronal hyperexcitability due to local inflammatory trauma after oral surgery. Orofacial sensory functions were investigated by psychophysical means in 60 patients (30 male, 30 female) in innervation areas of infraorbital nerves, mental nerves and lingual nerves after different interventions in oral surgery. The patients were tested 1 week, 4 weeks, 7 weeks, and 10 weeks postoperatively. As controls for bilateral sensory changes after unilateral surgery, tests were additionally performed in 20 volunteers who did not have any dental restorations. No differences were found between the control group and the control side of the patients. Although not 1 of the patients reported paresthesia or other sensory changes postoperatively, QST detected significant differences between the control and the test side in the mental and lingual regions. Test sides were significantly less sensitive for thermal parameters (cold, warm, and heat). No differences were found in the infraorbital region. Patients showed significantly decreased pain pressure thresholds on the operated side. QST monitored recovery over time in all patients. The results show that oral surgery can lead to sensory deficits in the mental and lingual region, even if the patients do not notice any sensory disturbances. The applied QST battery is a useful tool to investigate trigeminal nerve function in the early postoperative period. In light of the increasing forensic implication, this tool can serve to objectify clinical findings.

• The influence of bisphosphonates on human osteoblast migration and integrin aVb3/tenascin C gene expression in vitro.

  Authors: Felix P Koch, Annette Wunsch, Christina Merkel, Thomas Ziebart, Andreas Pabst, Sareh Said Yekta, Marco Blessmann, Ralf Smeets

  Head & face medicine. 02/2011; 7(1):4.

  Bisphosphonates are therapeutics of bone diseases, such as Paget's disease, multiple myeloma or osteoclastic metastases. As a severe side effect the bisphosphonate induced osteonecrosis of the jawBisphosphonates are therapeutics of bone diseases, such as Paget's disease, multiple myeloma or osteoclastic metastases. As a severe side effect the bisphosphonate induced osteonecrosis of the jaw (BONJ) often requires surgical treatment and is accompanied with a disturbed wound healing.Therefore, the influence on adhesion and migration of human osteoblasts (hOB) after bisphosphonate therapy has been investigated by morphologic as well as gene expression methods. By a scratch wound experiment, which measures the reduction of defined cell layer gap, the morphology and migration ability of hOB was evaluated. A test group of hOB, which was stimulated by zoledronate 5 × 10(-5)M, and a control group of unstimulated hOB were applied. Furthermore the gene expression of integrin aVb3 and tenascin C was quantified by Real-Time rtPCR at 5 data points over an experimental period of 14 days. The bisphosphonates zoledronate, ibandronate and clodronate have been compared with an unstimulated hOB control. After initially identical migration and adhesion characteristics, zoledronate inhibited hOB migration after 50 h of stimulation. The integrinavb3 and tenascin C gene expression was effected by bisphosphonates in a cell line dependent manner with decreased, respectively inconsistent gene expression levels over time. The non-nitrogen containing bisphosphonates clodronate led to decreased gene expression levels. Bisphosphonates seem to inhibit hOB adhesion and migration. The integrin aVb3 and tenascin C gene expression seem to be dependent on the cell line. BONJ could be enhanced by an inhibition of osteoblast adhesion and migration. The gene expression results, however, suggest a cell line dependent effect of bisphosphonates, which could explain the interindividual differences of BONJ incidences.

• Assessment of trigeminal nerve functions by quantitative sensory testing in patients and healthy volunteers.

  Authors: Sareh Said Yekta, Ralf Smeets, Jamal M Stein, Jens Ellrich

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 10/2010; 68(10):2437-51.

  Orofacial sensory dysfunction plays an important role in oral and maxillofacial surgery. Quantitative sensory testing (QST) is a psychophysical approach to evaluate thermal and mechanicalOrofacial sensory dysfunction plays an important role in oral and maxillofacial surgery. Quantitative sensory testing (QST) is a psychophysical approach to evaluate thermal and mechanical somatosensation. The present human study 1) collected normative QST data in extraoral and intraoral regions, 2) analyzed effects of age, gender, and anatomical sites on QST, and 3) applied QST in 11 patients with iatrogenic inferior alveolar nerve lesions. Sixty (30 male and 30 female) healthy volunteers were tested bilaterally in the innervation areas of infraorbital, mental, and lingual nerves. Ten patients with sensory disturbances in innervation areas of the mental nerve were investigated at 1, 4, and 8 weeks after surgery. Another patient with a complete sensory loss after surgery was repetitively tested within 453 days after primary surgery (dental implant) and subsequent surgical reconstruction of the inferior alveolar nerve by autologous graft. Older subjects were significantly less sensitive than younger subjects for thermal parameters. Thermal detection thresholds in infraorbital and mental regions showed higher sensitivity in women. Sensitivity to thermal stimulation was higher in the infraorbital region than in the mental and lingual regions. QST monitored somatosensory deficits and recovery of inferior alveolar nerve functions in all patients. Age, gender, and anatomic region affect various QST parameters. QST might be useful in the diagnosis of inferior alveolar nerve disorders in patients. In dentistry, the monitoring of afferent nerve fiber functions by QST might support decisions on further interventions.

• Impaired somatosensation in tongue mucosa of smokers.

  Authors: Sareh Said Yekta, Andreas Lückhoff, Dejan Ristić, Friedrich Lampert, Jens Ellrich

  Clinical oral investigations. 10/2010; 16(1):39-44.

  Smoking has been indicated as a risk factor for oral diseases and can lead to altered sense of taste. So far, the effects of sensory changes on the tongue are not investigated. In this study,Smoking has been indicated as a risk factor for oral diseases and can lead to altered sense of taste. So far, the effects of sensory changes on the tongue are not investigated. In this study, quantitative sensory testing was used to evaluate somatosensory function in the lingual region. Eighty healthy volunteers were investigated (20 smokers, 20 non-smokers). Subjects were bilaterally tested in innervation areas of lingual nerves. Thresholds of cold and warm detection, cold and heat pain, and mechanical detection were determined. As control for systemic, extraoral effects of smoking, tests were additionally performed in 40 volunteers (20 smokers, 20 non-smokers) on the skin of the chin innervated by the mental branch of the trigeminal nerve. Cold (p < 0.001), warm detection thresholds (p < 0.001), and thermal sensory limen (p < 0.001) showed higher sensitivity in non-smokers as compared to smokers. Heat pain and mechanical detection, as well as all tests in the skin of the chin, showed no significant differences. The impaired temperature perception in smokers indicates a reduction of somatosensory functions in the tongue, possibly caused by nerve degeneration associated with smoking. Possible systemic effects of smoking do not seem to affect extraoral trigeminal branches.

• In vitro study of adhesive polymethylmethacrylate bone cement bonding to cortical bone in maxillofacial surgery.

  Authors: Ralf Smeets, Rudolf Marx, Andreas Kolk, Sareh Said-Yekta, Maurice B Grosjean, Christian Stoll, Joachim Tinschert, Dieter C Wirtz, Dieter Riediger, Kira Endres

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 10/2010; 68(12):3028-33.

  In the treatment of midface fractures, the fragments are immobilized using screws and plates for osteosynthesis until reunion has occurred. This method involves drilling holes for the insertion ofIn the treatment of midface fractures, the fragments are immobilized using screws and plates for osteosynthesis until reunion has occurred. This method involves drilling holes for the insertion of the screws, which can be associated with additional fracturing of the corresponding bone owing to the complex architecture and thin layers of facial bone. To alleviate this problem, new adhesive techniques for fixing the plates for osteosynthesis have been investigated, mitigating the detrimental effects of screw hole drilling. In the present experimental study, the strength of this adhesive bond and its resistance to hydrolysis were investigated. To determine the adhesive bonding strength, a tension test was implemented. Osteosynthesis plates with screw holes 1.3 mm in diameter were fixed to cortical bone samples of bovine femur using ultraviolet (UV) light-curing polymethylmethacrylate bone cement. To facilitate bonding, the surface of the bone was conditioned with an amphiphilic bonding agent before cementing. UV light curing was implemented using either a conventional UV unit, such as is used in dentistry, or with a specialized UV unit with a limited emission spectrum but high luminosity. Reference control samples were prepared without application of the bone bonding agent. After this procedure, the samples were stored for 1 to 7 days at 37°C submerged in 0.9% saline solution before being subjected to the tension test. Without the bone bonding agent, the bonding strength was 0.2 MPa. The primary average bonding strength at day 0 was 8.5 MPa when cured with the conventional UV unit and 14 MPa for the samples cured with the specialized UV unit. An almost constant average bond strength of 8 and 16 MPa was noted for all samples stored up to 7 days after curing with the conventional and specialized UV unit, respectively. With the development of a new bone bonding agent, a method is now available to promote the bonding between the hydrophilic bone surface and the hydrophobic polymethylmethacrylate bone cement by creating an interlayer that is beneficial for adhesion. In the present in vitro study, the strength of this bond and its resistance to hydrolysis were investigated. This new method could have clinical bearing in cases in which conventional fixation with screws and plates is limited, such as can occur in comminuted fractures. The observed average bonding strengths of 8 to 16 MPa support the implementation of this technique in nonload-bearing regions such as the midface, facilitating immobilization until the bone reunion is complete.

• Analysis of trigeminal nerve disorders after oral and maxillofacial intervention.

  Authors: Sareh Said Yekta, Felix Koch, Maurice B Grosjean, Marcella Esteves-Oliveira, Jamal M Stein, Alireza Ghassemi, Dieter Riediger, Friedrich Lampert, Ralf Smeets

  Head & face medicine. 10/2010; 6:24.

  Quantitative sensory testing (QST) is applied to evaluate somatosensory nerve fiber function in the spinal system. This study uses QST in patients with sensory dysfunctions after oral andQuantitative sensory testing (QST) is applied to evaluate somatosensory nerve fiber function in the spinal system. This study uses QST in patients with sensory dysfunctions after oral and maxillofacial surgery. Orofacial sensory functions were investigated by psychophysical means in 60 volunteers (30 patients with sensory disturbances and 30 control subjects) in innervation areas of the infraorbital, mental and lingual nerves. The patients were tested 1 week, 4 weeks, 7 weeks and 10 weeks following oral and maxillofacial surgery. QST monitored somatosensory deficits and recovery of trigeminal nerve functions in all patients. Significant differences (p < 0.05) between control group and patients were shown for cold, warm and mechanical detection thresholds and for cold, heat and mechanical pain thresholds. Additionally, QST monitored recovery of nerve functions in all patients. QST can be applied for non-invasive assessment of sensory nerve function (Aβ-, Aδ- and C-fiber) in the orofacial region and is useful in the diagnosis of trigeminal nerve disorders in patients.

• The impact of bisphosphonates on the osteoblast proliferation and Collagen gene expression in vitro.

  Authors: Felix Peter Koch, Sareh Said Yekta, Christina Merkel, Thomas Ziebart, Ralf Smeets

  Head & face medicine. 01/2010; 6:12.

  Bisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are known to be associated with osteonecrosis of the jawBisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are known to be associated with osteonecrosis of the jaw (BONJ).The objective of this study was to evaluate the effect of bisphosphonates on osteoblast proliferation by cell count and gene expression analysis of cyclin D1 in vitro. Furthermore, the gene expression of the extracellular matrix protein collagen type I was evaluated. Nitrogen-containing and non-nitrogen-containing bisphosphonates have been compared on gene expression levels. Human osteoblast obtained from hip bone were stimulated with zoledronate, ibandronate and clodronate at concentrations of 5 x 10-5M over the experimental periods of 1, 2, 5, 10 and 14 days. At each point in time, the cells were dissolved, the mRNA extracted, and the gene expression level of cyclin D1 and collagen type I were quantified by Real-Time RT-PCR. The gene expression was compared to an unstimulated osteoblast cell culture for control. The proliferation appeared to have been influenced only to a small degree by bisphosphonates. Zolendronate led to a lower cyclin D1 gene expression after 10 days. The collagen gene expression was enhanced by nitrogen containing bisphosphonates, decreased however after day 10. The non-nitrogen-containing bisphosphonate clodronate, however, did not significantly influence cyclin D1 and collagen gene expression. The above data suggest a limited influence of bisphosphonates on osteoblast proliferation, except for zoledronate. The extracellular matrix production seems to be initially advanced and inhibited after 10 days. Interestingly, clodronate has little influence on osteoblast proliferation and extracellular matrix production in terms of cyclin D1 and collagen gene expression.

• Gender specific quality of life in patients with oral squamous cell carcinomas.

  Authors: Oliver Maciejewski, Ralf Smeets, Frank Gerhards, Andreas Kolk, Frank Kloss, Jamal M Stein, Adrian Kasaj, Felix Koch, Maurice Grosjean, Dieter Riediger, Sareh Said Yekta

  Head & face medicine. 01/2010; 6:21.

  The goal of this study was to evaluate the somatic and psychological effects by means of QUALITY OF LIFE (QOL) of surgical treatment of patients with oral squamous cell carcinoma. The factors gender,The goal of this study was to evaluate the somatic and psychological effects by means of QUALITY OF LIFE (QOL) of surgical treatment of patients with oral squamous cell carcinoma. The factors gender, age, nicotine consumption, and tumour stage were taken into consideration. 54 patients after surgical resection of oral squamous cell carcinomas (OSCC) were analysed from 01.09.2005 to 31.05.2008. Inclusion criteria for the study were: age at least 18 years, no indication or treatment of synchronous and metachronous tumours. German translations of the EORTC H&N-35 and EORTC QLQ-C-30 questionnaires, as well as a general socioeconomic patient history were used as measuring instruments. The questionnaires were completed independently by the patients. The answers were translated into scale values for statistical evaluation using appropriate algorithms. Analysis of the EORTC-QLQ-C-30 questionnaires demonstrated a tendency of more negative assessment of emotional function among the female participants, and a more negative evaluation of social function among the male participants. Greater tumour sizes showed significantly lower bodily function (p = 0.018). While a smaller tumour size was significantly associated with lower cognitive functioning (p = 0.031). Other cofactors such as age, nicotine consumption, and tumour stage only showed a tendency to influence the quality of sleep and daily life. The data obtained within this investigation demonstrated that gender had the most significant power on the subjectively perceived postoperative quality of life. This factor is important e.g. in preoperative decision making regarding immediate microvascular reconstruction after e.g. mandibular resection and therefore QOL assessment should become integral component of the care of patients with OSCC.

• Cerebral activations resulting from virtual dental treatment.

  Authors: Sareh Said Yekta, Rene Vohn, Jens Ellrich

  European journal of oral sciences. 12/2009; 117(6):711-9.

  Pain, and anxiety of pain, for some people are serious problems in dental treatment. It is a common practical experience that even entering a dental surgery office, or the sound of a dental drill,Pain, and anxiety of pain, for some people are serious problems in dental treatment. It is a common practical experience that even entering a dental surgery office, or the sound of a dental drill, may evoke vegetative correlates of toothache without any underlying disease. This everyday phenomenon suggests the hypothesis of a corresponding activation of pain-related brain areas by virtual dental treatment. Twenty healthy subjects viewed two different video clips presenting a dental treatment from the first-person perspective (simulation movie) and a moving hand holding an electrical toothbrush (control movie). Using functional magnetic resonance imaging, the cerebral hemodynamic responses that occurred during simulation and control movies were compared. Virtual dental treatment was associated with increased activity in pain-related brain areas such as the cingulate cortex, the insula, and primary and secondary somatosensory cortexes (SI, SII). The brain activation pattern indicates not only affective-motivational but also sensory-discriminative pain components during virtual dental treatment in all volunteers. Volunteers with a higher level of dental anxiety showed stronger activation of SI and SII. This may be a result of their higher anticipation of pain.

• Clinical evaluation of a biphasic calcium composite grafting material in the treatment of human periodontal intrabony defects: a 12-month randomized controlled clinical trial.

  Authors: Jamal M Stein, Stefan Fickl, Sareh Said Yekta, Ulrich Hoischen, Christina Ocklenburg, Ralf Smeets

  Journal of periodontology. 11/2009; 80(11):1774-82.

  BACKGROUND: The aim of this study was to compare the clinical outcome of a novel biphasic calcium composite (BCC) biomaterial versus autogenous bone spongiosa (ABS) or open flap debridement (OFD) forBACKGROUND: The aim of this study was to compare the clinical outcome of a novel biphasic calcium composite (BCC) biomaterial versus autogenous bone spongiosa (ABS) or open flap debridement (OFD) for the treatment of intrabony periodontal defects. METHODS: Forty-five subjects with at least one intrabony defect with a probing depth (PD) >or=7 mm and a vertical radiographic bone loss >or=3 mm were enrolled in the study. Subjects were randomly assigned to treatment with BCC (n = 15), ABS (n = 15), or OFD (n = 15). Clinical parameters were recorded at baseline and 12 months after surgery and included the plaque index, gingival index, PD, clinical attachment level (CAL), and gingival recession. RESULTS: In all treatment groups, significant PD reductions and CAL gains occurred during the study period (P <0.0001). At 12 months, patients treated with BCC exhibited a mean PD reduction of 3.6 +/- 0.7 mm and a mean CAL gain of 3.0 +/- 0.8 mm compared to baseline. Corresponding values for patients treated with ABS were 3.4 +/- 0.8 mm and 2.9 +/- 0.9 mm, whereas OFD sites produced values of 2.8 +/- 0.8 mm and 1.6 +/- 0.7 mm. Compared to OFD, the additional CAL gain was significantly greater in patients treated with BCC (P = 0.002) and ABS (P = 0.001). The additional PD reduction was significant for the BCC group (P = 0.011) and borderline significant for the ABS group (P = 0.059). There were no significant differences of PD and CAL changes between BCC and ABS groups. CONCLUSIONS: The clinical benefits of BCC were equivalent to ABS and superior to OFD alone. BCC may be an appropriate alternative to conventional graft materials.

• Homotopic long-term depression of trigeminal pain and blink reflex within one side of the human face.

  Authors: Matthias Aymanns, Sareh Said Yekta, Jens Ellrich

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 10/2009;

  OBJECTIVE: Electrical low-frequency stimulation (LFS) of cutaneous afferents elicits long-term depression (LTD) of craniofacial nociception and pain. The study addresses spatial organization of LTDOBJECTIVE: Electrical low-frequency stimulation (LFS) of cutaneous afferents elicits long-term depression (LTD) of craniofacial nociception and pain. The study addresses spatial organization of LTD within one side of the face. METHODS: The blink reflex was evoked by electrical test stimulation in the supraorbital nerve area before and after conditioning LFS in 10 healthy volunteers. Noxious LFS (1Hz) was applied to skin afferents of supraorbital (sLFS), infraorbital (iLFS), or mental (mLFS) nerves. All stimuli were applied to the same side of the face with intensities of three times pain threshold. Volunteers rated the test stimulus intensity. Each volunteer participated in four sessions with sLFS, iLFS, mLFS, or without LFS (control). RESULTS: Pain ratings of electrical test stimulation were differently affected in experimental sessions (p<0.01) with strongest reduction by -19.6% after sLFS. The reflex integral decreased by -34.7% significantly stronger after sLFS than in all other experimental conditions (p<0.001). Electrical pain thresholds increased significantly stronger in sLFS than in iLFS, mLFS, and control (p<0.001). CONCLUSIONS: Trigeminal nociception and pain were inhibited by homotopic LFS at the forehead but not after heterotopic LFS of infraorbital and mental nerve skin afferents. SIGNIFICANCE: Homotopic organization of ipsilateral trigeminal LTD in man may have implications for future neuromodulatory treatment of chronic craniofacial pain.

• Impaired thermal perception in cluster headache.

  Authors: Jens Ellrich, Dejan Ristic, Sareh Said Yekta

  Journal of neurology. 11/2006; 253(10):1292-9.

  Cluster headache is characterized by attacks of severe periorbital pain. Repetitive burst activity in afferent fibers may induce plastic alterations in somatosensory synaptic processing as aCluster headache is characterized by attacks of severe periorbital pain. Repetitive burst activity in afferent fibers may induce plastic alterations in somatosensory synaptic processing as a prerequisite for recurring and chronic pain. This psychophysical study addressed hypothesized dysfunctions in craniofacial somatosensory processing in cluster headache disease. Thermal and mechanical sensory functions in the periorbital region were assessed by quantitative sensory testing (QST) in 25 cluster headache patients and 60 healthy volunteers. Perception of warmth (p<0.01), cold (p<0.000001), and pressure pain (p<0.05) was reduced on the cluster side as compared with the contralateral asymptomatic side. In contrast to healthy volunteers, warm detection threshold (WDT) and thermal sensory limen (TSL) on one side did not positively correlate with the other side. WDT and TSL negatively correlated with the elapsed time since last attack. All patients showed QST abnormalities on the headache side in comparison to healthy controls. Loss of sensory functions strongly preponderated gain. Several lines of evidence indicate a pivotal role of the hypothalamus in cluster headache pathophysiology. The impairment of warm and cold perception in patients may be based upon a dysfunction of the hypothalamus which is strongly involved in thermosensory control.

• Heterosynaptic long-term depression of craniofacial nociception: divergent effects on pain perception and blink reflex in man.

  Authors: Sareh Said Yekta, Susanne Lamp, Jens Ellrich

  Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale. 05/2006; 170(3):414-22.

  Noxious low-frequency stimulation (LFS) of presynaptic nerve fibers induces long-term depression (LTD) of synaptic transmission. In vitro studies suggest a sole homosynaptic effect. Consequently, theNoxious low-frequency stimulation (LFS) of presynaptic nerve fibers induces long-term depression (LTD) of synaptic transmission. In vitro studies suggest a sole homosynaptic effect. Consequently, the present study addressed the hypothesis that LTD of craniofacial nociception in man is mediated by a homosynaptic mechanism. Nociceptive supraorbital afferents were excited by electric pulses via a concentric electrode in ten healthy volunteers. The electrically evoked bilateral blink reflex (BR) was recorded from both orbicularis oculi muscles by surface electrodes. The BR was evoked in blocks of ten electric stimuli each (0.1 Hz) with an interblock interval of 8 min. Conditioning noxious LFS (1 Hz, 20 min) was applied via concentric electrode either to the same site as BR test stimuli (ipsilateral) or to the corresponding contralateral forehead area (contralateral). LFS and test stimulus intensities corresponded to about threefold the pain threshold. After three baseline stimulus blocks, either conditioning ipsilateral or contralateral LFS were applied or stimulation was interrupted for 20 min as a control task. Afterwards, test stimulation blocks were continued for 40 min. Each volunteer participated in all three sessions on different days. Noxious LFS induced LTD of the BR independently from the side of conditioning stimulation. Pain perception decreased after ipsilateral LFS but not after contralateral LFS. The bilateral effect of noxious LFS on the BR provides evidence for heterosynaptic LTD based on bilateral projections of supraorbital nerve afferents onto spinal trigeminal nuclei. The divergent effect on pain perception may be due to a preferential contralateral projection of nociceptive afferents onto reflex interneurons but not onto trigeminothalamic projection neurons.