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PubMed2000

Oromandibular reconstruction.

Oromandibular reconstruction is one of the greatest challenges of the head and neck surgeon. The ideal rehabilitation of the mandible and associated soft tissues requires maintaining premorbid occlusion, providing the opportunity for dental restoration, and preventing salivary incontinence. The approach to each patient must be individualized to maximize speech, swallowing, and mastication. Additionally, the surgeon must strive to fulfill these goals while achieving the most pleasing cosmetic result possible. Although some patients may be treated without reconstruction or with a metal plate and soft tissue flap, the majority of patients benefit from bony reconstruction utilizing a free flap. Reconstruction with free flaps results in more primary healing and fewer wound complications. Challenges specific to reconstructing the temporomandibular joint are discussed. We also review the indications for the different rehabilitative options and the merits of the individual flaps.

Arthroplasty↗
PubMed2002

Outcomes research in head and neck reconstruction.

Modern management of advanced upper aerodigestive tract malignancy often results in profound effects on function and appearance. These functions include speech, deglutition, mastication, taste, oral hygiene, and airway maintenance. The most commonly studied site in the head and neck is the oromandibular complex. The primary goals of reconstruction are the preservation and restoration of these functions along with socially acceptable cosmesis. Achieving these objectives is not to be accomplished at the expense of acceptable oncologic principles. With the availability of microvascular free tissue techniques, single-stage oromandibular reconstruction is now commonly performed. Few studies, however, have critically examined the functional outcomes of these techniques. To date, these investigations have been limited and retrospective. Lack of a uniform system for reporting defect size and locations as well as patient function and quality of life has limited the utility of the available data. In this article, outcomes research in head and neck reconstruction is discussed with regard to objective study parameters using the oral cavity as a model. Pertinent current literature is cited.

Activities of Daily Living↗
PubMed2000

Effect of unilateral posterior crossbite on the electromyographic activity of human masticatory muscles.

Studies dealing with the electromyographic activity of masticatory muscles in patients with unilateral posterior crossbite are infrequent. The purpose of this study was to assess the electromyographic pattern of masticatory muscles at rest position, during swallowing, and during mastication, in 30 subjects with right posterior crossbite and to compare them to 30 normocclusive subjects. The 2 groups were matched according to age, gender, skeletal Class I, and mesofacial growth pattern. Electromyographic activity of right and left anterior temporalis, posterior temporalis, masseter, and anterior digastric muscles was recorded at rest position, while swallowing water, and while chewing. Disposable bipolar surface electrodes were used in both groups. Data were compared between groups and between right and left sides within each group. The results revealed that the posterior temporalis of the non-crossbite side was more active than that of the same side in subjects with crossbite at rest position and during swallowing. The activity of both anterior digastrics was higher in the crossbite subjects during swallowing. During chewing the right masseter muscle was less active in the crossbite patients than in normocclusive subjects. The results obtained during chewing indicate a bilateral masticatory pattern in both groups.

Adolescent↗
PubMed2000

Kinesiographic study of the mandible in young patients with unilateral posterior crossbite.

It is generally assumed that children with posterior crossbites have abnormal mandibular movements; however, this assumption has not been clearly evaluated. The purpose of this investigation was to study the movements and the resting position of the mandible in 2 samples of 30 subjects, one aged 10 to 14 years with right posterior crossbite, the other aged 10 to 15 years with normal occlusion. Subjects in both groups exhibited a Class I skeletal relationship and mesofacial growth pattern. A mandibular kinesiograph was used to record both the mandibular resting position and dynamic movements. Mandibular movements were recorded during (1) maximum excursions (opening-closing, protrusion, right and left excursions), (2) swallowing, and (3) mastication. The results showed no differences between groups in the extension of the movements during closing and protrusion. However, crossbite patients exhibited a significant lateral shift during these movements. Right and left excursions were also similar between groups. The dimension of the freeway space was similar between groups, but the lateral shift found in centric occlusion was also present in the crossbite group when the mandible was at rest. The crossbite group more frequently showed a pattern of abnormal swallowing. No differences were found in any of the parameters studied during the masticatory cycle. There was no relationship between the side of the crossbite and the masticatory preference side. In conclusion, posterior crossbite patients showed a lateral shift in some movements that persisted when the mandible was at rest.

Adolescent↗
PubMed2002

The temporalis muscle flap in reconstruction of intraoral defects: an appraisal of the technique.

PURPOSE: The purpose of this article is to review the experience of the authors in the use of the temporalis muscle flap for reconstruction of intraoral defects. PATIENTS AND METHODS: This is a retrospective review of the use of the temporalis muscle flap for reconstruction of different types of intraoral defects in 8 patients. All patients in this series previously wore obturators as a nonsurgical treatment of their defects. Criteria used to evaluate the results of this technique included flap necrosis, facial nerve deficit, limitation of mandibular range of motion, and cosmetic deformity from scarring of the incision line or from loss of muscle volume in the temporal fossa. The patients were also evaluated for their degree of satisfaction with their speech and mastication with the obturator preoperatively and with the flap postoperatively. This article also reviews the success rates and complications with use of the temporalis muscle flap reported in the English-language literature during the past 14 years. RESULTS: All 8 patients in this series had their defects successfully reconstructed, completely eliminating any further need for prosthetic obturation of the defect. There were no incidents of flap necrosis, facial nerve deficit, or long-term changes in mandibular range of motion. Slight temporal hollowing was seen in the first 3 patients. Results of the literature review also showed a high success rate and a low incidence of complications with use of this flap. CONCLUSIONS: The temporalis flap is a useful, reliable, and versatile option for reconstruction of moderate to large sized defects. The muscle can provide abundant tissue, with minimal to no functional morbidity or esthetic deformity in the donor site.

Adult↗
PubMed2001

Retrospective case series of primary and secondary microvascular free tissue transfer reconstruction of midfacial defects.

STATEMENT OF PROBLEM: Midfacial defects arising from tumor extirpation or trauma may involve any portion of the central area of the face, including the palate, maxilla, orbit, lip, and/or nose. Speech, mastication, swallowing, and cosmesis are significantly impaired and present a unique challenge to the reconstructive surgeon. PURPOSE: This study evaluated the functional and cosmetic success of both soft tissue and osteocutaneous free flap reconstruction of the midface. MATERIAL AND METHODS: A retrospective chart review of 34 patients who underwent primary and secondary free flap reconstruction of the midface was conducted. The main outcome measures were perioperative complications, diet, speech intelligibility, type of dental restoration, and cosmetic result. RESULTS: Fifteen patients underwent soft tissue free flap reconstruction of the midface. Six of these patients also had additional nonvascularized free cranial bone grafts to improve restoration of the orbitozygomatic region. Nineteen patients who might have required osseointegrated implants to anchor a dental prosthesis underwent osteocutaneous free flap reconstruction. Thirty-three of 34 free flaps survived, and wound complications were minimal. After surgery, 20 patients were able to eat a regular diet and 14 a soft diet. All patients had intelligible speech over the telephone. Ten patients used a dental prosthesis (5 conventional and 5 implant-borne). Cosmesis was judged to be excellent in 12 patients, good in 15 patients, fair in 5 patients, and poor in 2 patients. CONCLUSION: In the patients reviewed, free flap reconstruction of the midface was completed in a single stage and created a reproducible, permanent separation of the oral and sinonasal cavities with adequate speech and swallowing.

Adolescent↗
PubMed2001

Prospective 3-year study of cross-arch fixed partial dentures in patients with advanced periodontal disease.

STATEMENT OF PROBLEM: Several choices exist for the treatment of advanced periodontal disease. One is a combined periodontal and prosthetic treatment that includes cross-arch fixed partial dentures (FPDs). However, the outcomes of such therapy have been reported mainly from studies in Scandinavian countries. PURPOSE: The aims of this study were: (1) to longitudinally evaluate, after periodontal and prosthodontic treatment that included cross-arch FPDs, treatment outcomes in Korean patients who suffered from severe periodontitis; and (2) to evaluate the patients' treatment assessments and the FPDs after 3 years. MATERIAL AND METHODS: This survey included 39 Korean patients provided with 50 FPDs. Clinical and radiographic examinations were performed at the time of delivery of the FPDs and at the 3-year follow-up examinations. The prostheses were divided into 3 groups according to design (end abutments, unilateral cantilever, and bilateral cantilevers) and the amount of supporting tissues at the time of insertion. On average, only 26% of the total original periodontal tissue remained at the time of insertion. The FPDs consisted of 11 to 14 units, with a mean of 5 to 7 abutments in the 3 groups. The mean periodontal ligament area of the abutments was 79% of the total ligament area of the replaced teeth. RESULTS: At the 3-year follow-up examination, the FPDs were stable in all patients, who in general displayed good oral hygiene and had healthy periodontal conditions. The change in periodontal ligament area over the 3-year observation period was negligible (1 mm(2) per dental unit) and showed no statistically significant difference in relation to FPD design. Most patients were satisfied with the function of their FPDs with respect to mastication, phonetics, hygiene, esthetics, and chewing comfort. A few patients stated that they were careful with the FPDs and avoided certain foods (for example, raw peanuts and grilled squid) because they felt insecure with the cantilever segments. Most patients reported that they would choose the same treatment again. CONCLUSION: Patients with advanced periodontal disease demonstrated successful outcomes over a 3-year period and reported satisfaction with combined periodontal and restorative treatment that included cross-arch FPDs.

Adult↗
PubMed1986

Swallowing food without chewing; a simple way to reduce postprandial glycaemia.

1. The degree to which disruption by mastication affects the glycaemic response to four different carbohydrate foods was investigated in healthy human volunteers; each food was eaten by six subjects. 2. Subjects ate meals of sweetcorn, white rice, diced apple or potato on two occasions; on one occasion they chewed the food thoroughly, on the other occasion they swallowed each mouthful without chewing it. 3. When the foods were chewed the postprandial blood glucose levels rose to levels which varied according to the food ingested. 4. Swallowing without chewing reduced the glycaemic response to each food, achieving a similar effect as administration of viscous polysaccharides or 'slow-release' carbohydrates.

Adult↗
PubMed2003

Artificial neural network learns to differentiate normal TMJs and nonreducing displaced disks after training on incisor-point chewing movements.

Previous authors have described four frontal gum-chewing patterns associated with normal and abnormal TMJ disk-condyle relationships. The objective of this study was to create an automatic detection capability (expert system) by training an artificial neural network to recognize nonreducing displaced disks from frontal chewing data. Sixty-eight (68) subjects, 29 with normal joints, 18 with unilateral nonreducing displaced disks and 21 with bilateral nonreducing displaced disks were selected from a continuous series of patients seeking treatment for TMD. Right-sided gum chewing was recorded from all patients. Left-sided chewing was also recorded from the right unilateral patients. 50% of the vertical, lateral and timing values at 10%, 65% and 100% of opening and at 30%, 70% and 90% of closing were used to train an artificial neural network. The remaining 50% were used for testing. All normal subjects were detected as normal (specificity = 100%). Two bilateral and two unilateral patients were not detected (sensitivity = 91.8%). Four (4) patients received the wrong classification (unilateral vs. bilateral) and one patient received both (undecided) for an overall accuracy = 86.8%. The artificial neural network detected, at an acceptable level of error, the presence and type of nonreducing disk displacement from frontal plane jaw recordings of gum chewing in a group of real patients seeking treatment for TMD. Since it is very inexpensive to conduct, mastication analysis appears to have the potential of an excellent cost/benefit ratio.

Diagnosis, Computer-Assisted↗
PubMed1993

Tailoring texture for the elderly: theoretical aspects and technological options.

The perception of what is known as "texture" is a result of a variety of primarily mechanical and acoustical events. These are sensed by receptors of different kinds that are unevenly distributed in the sensing organ(s) (tongue, jaws, fingers) and neighboring tissues. The perceived intensity of textural properties is time dependent and can be influenced by other stimuli, notably chemical and thermal. The exact mode in which mechanical and geometrical properties are translated into perceived texture is not known. There are, however, known trends based on empirical observations, and growing understanding of the operation of individual receptors and the physiology and biomechanics of the sensation process itself. This body of knowledge can provide rational guidelines for the development of special products for the elderly and other people with special needs. For example, it is possible to increase fragility and maintain crunchiness or to make chewy foods that require a reduced effort in mastication to minimize fatigue. The technology to make such products is already in place and its future use by the food industry will depend only on marketing opportunities.

Aged↗
PubMed1980

Effect of chronic tobacco-betel-lime "quid" chewing on human salivary secretions.

Salivary flow rates by mechanical stimulation with forced spitting method and by chemical stimulation with 10% citric acid were determined in 25 healthy adult subjects with a history of chronic tobacco-betel-lime "quid" chewing and in 25 healthy control adults with no history of chewing. The chewers secreted more saliva as compared to nonchewers on chemical, but not on mechanical stimulation. The salivary amylase, potassium, and sodium levels were lower in chewers, but the reductions of the first two components only were significant. These reductions were thought to be due to increased salivary flow with its dilutional effect. There was no difference between the two groups with respect to salivary pH. The salivary flow rates by either method had significant positive correlation with the duration of chewing, but not with the amount of tobacco chewed. Salivary potassium was inversely correlated with the amount of tobacco chewed. It was concluded that chronic tobacco-betel-lime quid chewing induces excessive secretion of more watery saliva leading to a concomitant decrease in enzyme and electrolyte content. One or more of the following factors were considered to be operating in causing increased salivary flow in chewers effect of nicotine or tobacco on other constituents of the quid, chronic salivary gland hyperplasia, or chronic hypertrophy of the muscles of mastication.

Adult↗
PubMed1990

Effects of attritive diet on craniofacial morphology: a cephalometric analysis of a Finnish skull sample.

The purpose of the present study was to analyse cephalometrically the effects of a high-attrition environment on craniofacial morphology. The material consisted of lateral cephalograms of 32 Finnish crania and of a control sample of 50 present-day Finns. The skull sample represented Finns who had lived in the city of Turku during the 15th and 16th centuries. Marked dental attrition was seen in the skulls; the dentition of the control individuals was virtually unworn. The gonial angle, and the angle between the mandibular base and nasal floor were significantly smaller in the skull sample than in the present-day sample. In addition, the upper incisors were more palatally inclined, and the angle between the axes of the upper and lower incisors was significantly larger in the skull sample. The configuration of the cranial base, and the relationship of the clivus to the nasal floor and ramus were similar in both samples. The results indicate that intensive mastication affects mandibular growth by advancing its anterior rotation. The large interincisal angle was caused, almost equally, by the lingual tipping of the upper incisors and the anterior rotation of the mandible. It is suggested that anterior rotation is the natural growth direction of the mandible. However, several functional disturbances, including reduced masticatory stimulation due to modern diet, may promote more posteriorly directed growth.

Adult↗
PubMed1997

Maxillary development revisited: relevance to the orthopaedic treatment of Class III malocclusions.

Normal development of the maxilla results not only from movements of its constituent skeletal units and bony apposition-resorption superficially, but also from the specific development of the antero-lateral regions. In Class III cases, correction of the skeletal dysmorphosis requires not only that the maxilla is in a correct position (in relation to the mandible) and that the correct occlusion is achieved, but also that there is good development of the exo-peri-premaxilla. This requires normalization of muscular posture (labio-mental, lingual, velo-pharyngeal) and of orofacial functions (nasal ventilation, swallowing, mastication). Postero-anterior traction using an orthopaedic mask can only accomplish part of the treatment of Class III. The action must always be complimented by other therapy aimed at correcting the underdevelopment of the antero-lateral regions. Facemask therapy is not only simple sagittal distraction, but is truly a method for treatment of Class III which is well understood and achieves excellent results. Taking into account the great diversity of anatomical forms of Class III malocclusion, it is not surprising that extra-oral postero-anterior traction gives widely varying results. The quality, however, depends principally on the method used. Orthodontists must not hesitate to call for the assistance of a surgeon each time the functional treatment is insufficient, particularly in cleft patients where the results depend more on surgical procedures, both primary and secondary, than on dentofacial orthopaedics.

Adolescent↗
PubMed1999

The mechanical behaviour of human mandibles studied by electronic speckle pattern interferometry.

An understanding of the mechanical behaviour of the human mandible during mastication may be useful in several specific medical fields that examine the maxillofacial area. In this research, the Electronic Speckle Pattern Interferometry Optical Technique was applied to study a dry mandible under external stress. Two images of the mandible, i.e. an image of the relaxed mandible and another of the mandible under stress, were processed using this technique and provided information concerning the most stressed areas of the bone. The advantage of interferometric analysis is that it can be carried out in real time on a mandible to which progressively greater stress has been applied. This research may be of value in maxillofacial surgery, for example, in the diagnosis and treatment of fractured mandibles, and in oral surgery and orthodontics, where it can provide information concerning stress dispersion when an osteointegrated implant or orthodontic appliance is placed in the mouth. One of the most important conclusions to be drawn from the experiments of tension, compression, and in- and out-of-plane deformations is that the capability of the mandible to bend is superior to its capability to stretch. Several quantitative results support this conclusion.

Female↗
PubMed2003

The value of the aesthetic component of the Index of Orthodontic Treatment Need in the assessment of subjective orthodontic treatment need.

Previous studies carried out using the Index of Orthodontic Treatment Need (IOTN) have reported that the Aesthetic Component (AC) has limited use in schoolchildren. The purpose of this study was to estimate whether dental concern expressed by the grade of the AC chosen by subjects is reliable and whether it may be predictive for potential co-operation. Such a correlation would indicate if the AC of the IOTN may help to identify individuals interested in orthodontic treatment who would co-operate well, and consequently who might derive the greatest benefits. The investigation was carried out in north-west Poland among 84 schoolchildren (42 girls and 42 boys) aged 12 years and was based on a questionnaire and clinical examination. The questionnaire contained items relating to the subjective assessment of dental appearance, demand for orthodontic treatment, the influence of the dentition on the general appearance, and any functional disorders (speech, mastication, muscular pain, etc.). Clinical examination was carried out at the schools each time by the same dentist. For statistical analysis chi-square (Yates corrected) and McNemar tests were used. A probability at the 5 per cent level or less (P < 0.05) was considered statistically significant. The outcome shows that the AC of the IOTN moderately reflects the subjective perception of dental aesthetics and demand for orthodontic treatment. The results indicate that using professional rating the AC scale does not seem to be more precise or reliable than self-evaluation. The correlation between dental concern and the AC would be higher if the 'no treatment need' category was split into two parts (e.g. 1-2 'no need', 3-4 'slight need') or the 'borderline need' category was moved two grades lower. The AC would then help to identify patients interested in treatment who would potentially be co-operative.

Attitude to Health↗
PubMed2003

Stresses on the cervical column associated with vertical occlusal alteration.

The biomechanical effects on cervical vertebral columns (C1-C7) during mastication were calculated using a three-dimensional (3D) finite element method. To verify the biomechanical influences of vertical occlusal alteration to the cervical column, three finite element models (FEM) showing a normal (model A), a steep (model B), and a flat occlusal plane (model C) were constructed. The occlusal stress distribution showed various patterns for the three models; the stress extended to the anterior area as the occlusal plane became steeper. The plots of the stresses on the mid sagittal section of the cervical columns showed different patterns for the three models; the stress converged at the odontoid process in models A and B, whereas the stresses at C7 in model B tended to decrease compared with model A. Concentrated stress was observed at C5 in model C, supporting the hypothesis that vertical occlusal alteration could influence stress distribution in the cervical columns.

Adult↗
PubMed2004

Effect of decreased loading on the metabolic activity of the mandibular condylar cartilage in the rat.

The aim of this study was to measure the effect of decreased temporomandibular loading on the proliferative activity and the level of matrix production of the condylar cartilage. The effect of reduced joint loading on the activity of stromelysin-1 (MMP-3), which has been associated with conditions of articular cartilage matrix breakdown, was also examined. Eighty 14-day-old female rats were assigned to two groups. Following weaning at 20 days, the experimental group was fed a soft diet and the incisors were shortened regularly to keep them out of occlusion. The controls were fed a hard diet. The activity of tritiated thymidine incorporation and the incorporation of radiolabelled sulphur were measured 2, 6, 12, 24 and 48 hours after initiation of the experiment. The radiolabelled sulphur intake was significantly lower in the condylar cartilage of the experimental group 6-24 hours after initiation of the experiment, and tritiated thymidine activity was lower after 12-24 hours, indicating lower proliferation and matrix production. The cartilage in the experimental group showed marked immunostaining against MMP-3 in all cartilage layers 9 days after initiation of the experiment. In the control group, the staining was clearly seen only in the superficial fibrous layer and in the erosion front. A marked reduction in proliferative activity and proteoglycan synthesis in mandibular condylar cartilage was found after a continuous soft diet and suppressed incisal mastication in the rat. The results show that sufficient loading is important for condylar cartilage growth, to maintain both ideal proliferation and matrix chondrocyte production.

Animals↗
PubMed2006

Reverse-sequencing chewing patterns before and after treatment of children with a unilateral posterior crossbite.

The aim of this study was to compare the percentage of reverse-sequencing chewing cycles in 22 children [9 boys and 13 girls; mean age +/- SD, 8.6 +/- 1.3 and 8.8 +/- 1.5 years, respectively), with a unilateral right or left posterior crossbite, before and after therapy. The chewing cycles were recorded using a kinesiograph while the subjects masticated a soft and a hard bolus on both the crossbite and non-crossbite side. Chewing data were acquired before and 6 months after orthodontic treatment of the crossbite with an orthodontic functional appliance, the 'Function Generating Bite'. The results showed that, before therapy, the percentage of reverse-sequencing chewing cycles on the crossbite side was significantly higher than that on the normal side (P < 0.001) with both the soft and hard bolus. In addition, the percentage of reverse-sequencing chewing cycles on the crossbite side before therapy was significantly greater than after therapy with both a soft and hard bolus (P < 0.001). No significant differences were found in the percentage of reverse-sequencing chewing cycles on the non-crossbite side, before or after therapy, either with a soft or hard bolus.

Child↗