The effect of repeated firings on the color of an alumina ceramic system with two different veneering porcelain shades.

STATEMENT OF PROBLEM: Possible sources of processing variables in porcelain firing include thickness and color of the opaque; thickness, color, and translucency of the body and enamel layers; firing temperature; and number of firings. PURPOSE: The purpose of this in vitro study was to investigate the color changes of an alumina ceramic system veneered with different veneering porcelain shades and fired different numbers of times. MATERIAL AND METHODS: Twenty disc-shaped ceramic specimens (10 mm in diameter, with a core thickness of 1 mm), with 2 different veneering porcelain shades (A1, A3), were fabricated from an alumina ceramic system (Turkom-Cera) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed, and color differences (ΔE) were determined using a spectrophotometer. Repeated-measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Duncan test and paired 2-tailed tests were used for multiple comparisons (α=.05). RESULTS: The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.005) and veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and the veneering porcelain shade for L* (P=.002), a* (P=.001), and b* (P=.001) values. A1 shade specimens maintained their L* value independent of the number of firings, whereas A3 shade specimens became lighter after an increased number of firings. For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in less reddish specimens, and the b* value decreased after repeated firings, which resulted in less yellowish specimens. CONCLUSIONS: Imperceptible (ΔE<1.6) and clinically acceptable color changes (ΔE<3.7) were demonstrated by the alumina ceramic system tested.

Facial motor cortex plasticity in patients with unilateral peripheral facial paralysis.

Hand motor representation area expands towards the area of the perioral facial motor cortex in patients with peripheral facial paralysis (PFP) and in hemifacial spasm cases treated with botulinum toxin. In this current study, we aimed to investigate the changes both in the ipsilateral and contralateral facial motor cortex areas in patients with PFP with transcranial magnetic stimulation (TMS). Thirty healthy individuals and 41 patients with unilateral PFP with partial or total axonal degeneration participated in this study. Motor evoked potentials (MEPs) of perioral muscles elicited by TMS of the intracranial portion of the facial nerve and motor cortex, were recorded. TMS was delivered through a figure-of-eight coil. Mapping of the cortical representation of perioral muscles were also studied in 13 of 41 patients and in 10 of control subjects. Mean amplitude of the intact perioral MEPs elicited by the ipsilateral hemisphere TMS, was significantly higher in patients than the control subjects. There was also a mild enlargement of the mean cortical representation area of intact perioral muscles on both hemispheres though it was not significant. We have concluded that there was a cortical reorganization in the hemisphere contralateral to the paralytic side resulting in an increase at corticofugal output related to intact perioral muscles.

Use of levodopa to relieve pain from painful symmetrical diabetic polyneuropathy.

Levodopa has been used to treat some painful conditions and found to be effective in neuropathic pain due to herpes zoster in a double-blind study. From our anecdotal observations about the efficacy of levodopa on diabetic neuropathic pain, we designed a double-blind placebo-controlled study to test levodopa in painful diabetic neuropathy. Twenty-five out-patients with painful symmetrical diabetic polyneuropathy were admitted to the study. Fourteen patients were given 100 mg levodopa plus 25 mg benserazide to be taken three times per day for 28 days. Eleven patients were given identical placebo capsules. A blinded neurologist evaluated the patients clinically and performed Visual Analogue Scale (VAS) measurement every week from day 0 to day 28. The results seemed promising and levodopa may be a choice for the control of pain in neuropathy for which we do not have many alternative treatments.

Changes in the perioral muscle responses to cortical TMS induced by decrease of sensory input and electrical stimulation to lower facial region.

OBJECTIVE: To determine the changes in the motor cortex due to repetitive electrical stimulation and cutaneous anesthesia in lower facial region. METHODS: A total of 11 subjects participated in the study of repetitive electrical stimulation, and 10 other subjects in the study of lower facial anesthesia. Facial nerve root and face associated cortical MEPs by transcranial magnetic stimulation (eight-shaped coil) were recorded from perioral muscles pre- and post- electrical stimulation and lower facial anesthesia. Cheek near to the corner of the mouth was transcutaneously stimulated by bipolar surface electrode giving repetitive electrical shocks at 5 Hz. Five percent lidocain/prilocain local anesthetic cream was applied to left or right lip-cheek region. RESULTS: There was no significant change in perioral MEP responses after 10-30 min of 5 Hz electrical stimulation. We found a significant increase of amplitude in cortical MEP recordings during lower facial anesthesia especially in cases of cortical magnetic stimulations ipsilateral and contralateral to the anaesthetized side and in perioral recordings contralateral to the anaesthetized side. CONCLUSIONS: The present study demonstrates that topical anesthesia to the lower facial region leads to cortical modulation and fast plastic changes in both hemispheres that are directed to the normal side.

The head stabilization reflex by stimulation of accessory nerve.

The head stabilization reflex (HSR) was described by a new technique of stimulating the accessory nerve and then the reflex muscle responses' were recorded electromyographically from the contralateral sternocleidomastoid muscle. Thirty-two normal control subjects and 22 patients with various neurological disorders were studied. The HSR obtained from the contralateral sternocleidomastoid muscle was very stable with a mean latency of about 45 ms and was regularly obtained by the supramaximal stimulation of the ipsilateral accessory nerve from the normal subjects. The HSR was absent in 9 out 11 patients with cerebellar syndrome. The HSR seemed to be a oligo-polysynaptic/plurosegmental reflex under the strong control of the cerebellum.

Trigemino-cervical reflexes in normal subjects.

Trigemino-cervical reflexes, recorded from the semispinalis capitis muscle (SCM) in the posterior neck, were studied in 35 healthy volunteers, in response to electrical stimulation of the supraorbital trigeminal nerve and glabellar tapping. Simultaneous responses evoked from the ipsilateral orbicularis oculi muscle (OOM) were also recorded i.e. blink reflexes. Electrical stimulation of the supraorbital nerve elicited a reflex response with a latency of about 50 ms from the ipsilateral SCM which was called C3. An early reflex response, which sometimes had two components with latencies of 18 ms and 35 ms, was elicited with glabellar taps. They were called C1 and C2 respectively. When C1 and C2 were elicited with usual glabellar taps, C3 was suppressed. With electrical stimulation, suppression of C1 and C2 was noted, though C3 could easily be obtained. Electrophysiological characteristics of C1 (and C2) were compatible with an oligosynaptic, innocuous reflex, whereas C3 seemed to be multisynaptic and nociceptive in nature. A negative interaction between these two reflexes was observed.

Trigeminocervical reflexes elicited by stimulation of the infraorbital nerve: head retraction reflex.

In the current study, the effects of stimulation of the infraorbital nerve (ION) on the trigeminocervical reflexes (TCRs), recorded from the posterior neck muscles, was investigated and the results were compared with the results recorded by stimulation of the supraorbital nerve (SON). TCRs obtained by stimulation of the ION was evaluated as the electrophysiologic counterpart of the head retraction reflex. Twenty normal control subjects, 10 men and 10 women, were enrolled in the study. The SON and the ION were stimulated by using a bipolar surface electrode. Results were recorded by using either concentric needle electrodes inserted into the semispinalis capitis muscle at the level of the third or fourth cervical vertebra or by surface electrodes placed at the C3 and C7 vertebrae on the midline. It was found that stimulation of the supraorbital and infraorbital branches of the trigeminal nerve had different reflexive effects on the posterior neck muscles. A stable positive (or negative-positive) wave, with a very early latency and high amplitude was always recorded after maximal stimulation of the ION, which could never be detected by stimulation of the SON. The C3 response of the TCR, evoked by SON stimulation was always evoked, by stimulation of the ION, at a low threshold. These findings suggest that the head retraction reflex is composed of two phases: inhibitory and excitatory. The early, fixed positive wave represents the general inhibition of the cranial and neck muscles, just before withdrawal of the face and head, from unexpected stimuli, which precedes the dense C3 response, demonstrating activation of the posterior neck muscles.

Sacral cord conduction time of the soleus H-reflex.

The sacral cord conduction time of the soleus H-reflex was investigated in 30 normal adult subjects using three different methods. (1) The posterior tibial nerve was stimulated at the popliteal fossa by graded electric shocks, and the recordings were made from different lumbar epidural intervertebral levels. The afferent action potentials from the dorsal roots and the reflexively evoked efferent action potentials from the ventral roots were recorded. The time interval between the negative peaks of the ventral and dorsal root potentials was used to calculate the approximate sacral cord reflex delay time, which was found to be 1.3 ms. on average. (2) The sacral cord reflex delay time was found to be about 2.0 ms using the conduction time of the afferent, that of the efferent limbs and total reflex time of the soleus H-response. (3) By stimulating the lumbosacral roots at the epidural levels and using the difference between the soleus H and M response latencies, the sacral cord reflex delay was determined to be approximately 2.4 ms. These findings indicated that the soleus H-reflex is exclusively monosynaptic. It is proposed that in humans the synaptic transmission at the sacral cord is approximately 0.4 ms.

Motor-evoked potentials from various levels of paravertebral muscles in normal subjects and in patients with focal lesions of the spinal cord.

STUDY DESIGN: This prospective study includes normal control subjects and patients with focal lesions of the spinal cord investigated by transcranial magnetic stimulation. OBJECTIVES: To establish a stable method to elicit motor evoked potentials from cervical to lumbar segmental levels and to apply the method that would allow the localization in patients with restricted cord lesion. Thirty-four healthy subjects (10 women, 24 men) and 17 patients with focal spinal lesions were admitted to this study. SUMMARY OF BACKGROUND DATA: The focal cord lesions and injuries were previously evaluated by the records of lower limb muscles after cortical stimulation, but this method did not demonstrate the vertebral levels at which the lesions were located. METHODS: The paravertebral myotomal-evoked potentials were recorded in different segmental levels (T1, T6, T12, and L3) from paravertebral muscles, using surface and needle electrodes by transcranial magnetic stimulation in normal control subjects and patients. RESULTS: In normal control subjects, paravertebral myotomal-evoked potentials were obtained from T1, T6, T12, and L3 paravertebral muscles with both recording techniques (surface and needle electrode). From T1 to L3 latencies of paravertebral myotomal-evoked potentials increased gradually (from 10 msec to 17 msec) in normal control subjects. The levels of spinal cord lesions were obtained reliably in 14 of 17 patients with thoracic-lumbar spinal cord lesions, by using both electrophysiologic methods. In 11 of 14 patients, the lesions produced total conduction block, at and below the lesion level. In the remaining 3 patients slowing of intersegmental conduction was observed along the focal cord lesion. CONCLUSIONS: The paravertebral myotomal-evoked potentials obtained by surface electrode from paravertebral muscles and by midline needle electrode in the intrinsic rotatory muscles of the spine were useful in localizing lesions in the spinal segments in most of the patients with thoracic-lumbar cord lesions.

Novel Fabrication Technique for Root-supported Overdentures: A Case Report / Técnica de fabricación novedosa para sobredentaduras apoyadas en la raíz: un reporte de caso

ABSTRACT Tooth and bone preservation is essential to support dentures, especially for elderly patients. Retaining the existing teeth and roots for an overdenture postpones edentulism, and this is a convenient alternative to complete dentures and extraction of teeth. Root-supported overdentures attach to the roots with precision attachments. The fit of the attachment of both the denture and the roots or implants is very important for overdentures. The combination of the attachments increases the retention and stability of attachment-retained overdentures. This technique describes an alternative procedure to fabricate root-supported overdentures with combined locator and casted telescopic attachments.

RESUMEN La preservación de los dientes y los huesos es esencial para apoyar las dentaduras postizas, especialmente para pacientes de edad avanzada. Retener los dientes y raíces existentes para una sobredentadura aplaza el edentulismo, y constituye una alternativa conveniente para completar las dentaduras postizas y la extracción de dientes. Las sobredentaduras apoyadas en la raíz se unen a las raíces con aditamentos de precisión. El ajuste del aditamento tanto de la dentadura como de las raíces o implantes es muy importante para las sobredentaduras. La combinación de los aditamentos aumenta la retención y la estabilidad de las sobredentaduras retenidas por aditamento. Esta técnica describe un procedimiento alternativo para fabricar sobredentaduras ancladas en la raíz con un localizador combinado y aditamentos telescópicos fundidos.

Central and peripheral motor conduction to cremasteric muscle.

The few electrophysiologic studies of the cremasteric muscle (CM) have mainly been restricted to the cremaster reflex with no reference to central and peripheral nerve conduction to the muscle, probably for technical reasons.Twenty-six normal adult male volunteers were studied by transcranial magnetic cortical stimulation (TMS) and stimulation of thoracolumbar roots. The genitofemoral nerve (GFN) was stimulated electrically at the anterior superior iliac spine and a needle electrode was inserted into the CM for conduction studies. The motor latency to the CM from the cortical TMS ranged from 20 to 33 ms among the subjects (25.8 +/- 2.9 ms, mean +/- SD). Magnetic stimulation of the lumbar roots produced a motor response of the CM within 9.6 +/- 1.9 ms (range, 6-15). The central motor conduction time to the CM was 16.5 +/- 2.8 ms (range, 10-21). Stimulation of the GFN produced a compound muscle action potential with a mean value of 6.4 +/- 1.8 (range, 4-10) ms in 23 of the 26 cases. Thus, central motor nerve fibers to the CM motor neurons exist, and there may be a representation area for the CM in the cerebral cortex. The GFN motor conduction time to the CM may have clinical utility, such as in the evaluation of the groin pain due to surgical procedures in the lower abdomen.

[Use of endodontically treated teeth in removable partial dentures]. / Hareketli bölümlü protezlerde endodontik tedavili dislerin destek olarak kullanilmasi.

In our study, cases where teeth with excessive crown loss served as abutments, where examined in Kennedy Class II modification 1, that have tooth and tissue support on removable partial dentures which were constructed with the same design. Our study aims to examine, how vertically directed forces are transmitted to the supporting tissues by using photoelastic method. Teeth with case post and core appliances were used as abutments for removable partial dentures. Vertical loading procedure following the construction of removable partial dentures with the same design, revealed distribution of force over dentulous and edentulous ridge areas. When a comparison between endodontically treated and sound abutment teeth, was made, we had the conclusion that teeth with excessive crown loss can successfully serve as abutments for partial dentures, because the results of our finding exhibited no significant difference.

[Investigation of the castings marginal adaptation using investment expansion methods]. / Revetman genlesme yöntemleri ile yapilan dökümlerin marginal uyumlarinin arastirilmasi.

The research in the field of metal casting has recorded a continual progress in dentistry. Particularly, due to the economic problems posed by the use of gold alloys relatively inexpensive metal alloys tend to gain increased popularity. Application of such alloys physically in dentistry and their adaptability to various preparations are being studied. In castings where investment expansion methods are employed, and marginal adaptability of castings are evaluated, the results of variance analysis have indicated little significant difference due to the applied methods. However, the hygroscopic method has proved highly successful in terms of marginal adaptability.

[Comparison of investment expansion methods aspect of porosity]. / Revetman genlesme tekniklerinin gözeneklilik yönünden karsilastirmasi.

Currently, the use of non-precious metal alloys in fixed prosthetic restorations has warranted review of the work done sofar using precious metal alloys. One of the parameters exhibiting the success of castings done using non-precious metal alloys is porosity, which is evaluated through such methods as rod forms, waxing heat, to investing and other castability methods. The porosity ratios of cats similarly done employing different investment expansion methods have been evaluated. While there is no statistical difference due to different methods, the hygroscopic expansion method noted successful results.

Slow motor conduction mainly limited to motor root in amyotrophic lateral sclerosis.

Motor conduction velocity is expected to be normal or nearly normal in amyotrophic lateral sclerosis (ALS). Some studies have suggested that pathology may be present in the proximal axons. Indeed, some investigators have shown a decrease in the proximal conduction velocity in ALS by using motor conduction velocity measurements and H-reflex and F-response recordings, but they could not delineate the precise region of the conduction pathology. In this study, unlike the ones carried out previously, the most proximal segment has been studied in 11 patients with ALS, 13 normal controls, and 5 patients with sequel of poliomyelitis (SPM) by recording sensory and motor spinal root potentials. While no conduction pathology, H-reflex, or F-response abnormalities were found in ALS patients compared to normal subjects, it was shown that conduction velocity decreased in the proximal segment of the lower motor neuron of the ventral root. Despite motor neuron pathology in SPM, there was no proximal motor conduction slowing compared with that in normal subjects.

[Overlay dentures]. / Overlay protezler.

Overlay dentures which are accepted as superposition appliances have been presented by three cases in this article. These kind of dentures are dedicated as prosthodontic restorations which are applied to extend maxillary arch horizontally in the cases of maxillary collapse. These restorations also increase the vertical dimension which has been lost and so help to improve the facial contour as well as esthetics of the individual-these dentures classified as removable partial or complete overlay dentures are generally applied in the cases of bilateral or unilateral maxillary collapse which have been caused by trauma or tumor resection.

Ulnar nerve lesion in the palm: report of an unusual case.

We report the case of a patient who had weakness of the fourth dorsal interosseous (DI) and third palmar interosseous (PI) muscles resulting in the abducted position of the little finger at rest. Electromyographic abnormalities were limited to only these muscles with partial denervation findings. The results of routine nerve conduction studies and imaging techniques were normal. Clinical and electrophysiological findings suggested that the lesion had occurred distal to the point where the very small motor branches to these muscles exit the deep palmar branch of the ulnar nerve.

A special kind of anterior horn cell involvement in juvenile myoclonic epilepsy demonstrated by macro electromyography.

Juvenile myoclonic epilepsy (JME) is not an uncommon seizure disorder, occurring in 5-10% of epileptic patients. A subclinical anterior horn cell involvement has been suggested in some JME patients by concentric needle electromyography (EMG) and turn/amplitude analysis. In this study, 22 JME patients and 17 normal control subjects have been studied with macro EMG, which is a sensitive method to assess the size of motor units. Most JME patients (19 of 22) had a pathologically increased number of individual large macro motor unit action potentials (MUAPs) compared to control subjects. For both biceps brachii and tibialis anterior muscles, means of median macro MUAP amplitudes were significantly greater than those of normal controls, whereas the fiber density values were only slightly increased. This suggested another kind of anterior horn cell involvement in JME than seen in motor neuron diseases.

Pathophysiological mechanisms of oropharyngeal dysphagia in amyotrophic lateral sclerosis.

We investigated the pathophysiological mechanisms of dysphagia in amyotrophic lateral sclerosis. Forty-three patients with sporadic amyotrophic lateral sclerosis were examined by clinical and electrophysiological methods that objectively measured the oropharyngeal phase of voluntarily initiated swallowing, and these results were compared with those obtained from 50 age-matched control subjects. Laryngeal movements were detected by a piezoelectric sensor and EMG of submental muscles, and needle EMG of the cricopharyngeal muscle of the upper oesophageal sphincter of both the amyotrophic lateral sclerosis and control groups was recorded during swallowing. Amyotrophic lateral sclerosis patients with dysphagia displayed the following abnormal findings. (i) Submental muscle activity of the laryngeal elevators, which produce reflex upward deflection of the larynx during wet swallowing, was significantly prolonged whereas the laryngeal relocation time of the swallowing reflex remained within normal limits. (ii) The cricopharyngeal sphincter muscle EMG demonstrated severe abnormalities during voluntarily initiated swallows. The opening of the sphincter was delayed and/or the closure occurred prematurely, the total duration of opening was shortened and, at times, unexpected motor unit bursts appeared during this period. (iii) During voluntarily initiated swallows there was significant lack of co-ordination between the laryngeal elevator muscles and the cricopharyngeal sphincter muscle. These results point to two pathophysiological mechanisms that operate to cause dysphagia in amyotrophic lateral sclerosis patients. (i) The triggering of the swallowing reflex for the voluntarily initiated swallow is delayed and eventually abolished, whereas the spontaneous reflexive swallows are preserved until the preterminal stage of amyotrophic lateral sclerosis. (ii) The cricopharyngeal sphincter muscle of the upper oesophageal sphincter becomes hyper-reflexic and hypertonic. As a result, the laryngeal protective system and the bolus transport system of deglutition lose their co-ordination during voluntarily initiated swallowing. We conclude that these pathophysiological changes are related mainly to the progressive degeneration of the excitatory and inhibitory corticobulbar pyramidal fibres.