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At least 19 recordsLinked to original sources

PubMed1991

Chin disfigurement following removal of alloplastic chin implants.

Insertion and subsequent removal of alloplastic chin implants is not an innocuous procedure, as commonly believed. Ten women, aged 23 to 62 years of age (mean 45 years) are reported in whom severe soft-tissue deformities were observed 6 months to 6 years (mean 32 months) after removal of their implants. Resulting deformities consisted of chin ptosis and bizarre soft-tissue pogonial bunching and dimpling in repose or on animation in 9 of the 10 patients (90 percent). Asymmetrical motion of the lower lip was noted by 5 of the 10 patients. Two patients complained of pain and tenderness over the soft-tissue pogonion. The "bizarre" soft-tissue chin deformities, once established, are virtually uncorrectable. Presently, we recommend serious consideration be given to performing an immediate osseous genioplasty in patients requiring removal of alloplastic chin implants to prevent the evolution of such abnormalities.

Adult↗

PubMed1990

Variations in chin-marking behavior of New Zealand female rabbits throughout the whole reproductive cycle.

Chin-marking (chinning) was measured daily in intact New Zealand female rabbits across their whole reproductive cycle. In Experiment 1 does displayed during estrus (48 days studied) three phases, adaptation, growth and plateau, characterized by progressively higher chinning scores (mean +/- SE = 3.6 +/- 1.1; 17.7 +/- 6.3; 26.6 +/- 4.9 marks/10 min, respectively). Despite great quantitative differences among individuals, these 3 phases and the occurrence of chinning "peaks" at 4-6 day intervals were consistently observed in all subjects (Ss). Mating provoked, within one hour, a dramatic decrease in chinning. Both pregnant and pseudopregnant Ss showed low chinning scores for the first 13 days after mating (combined mean +/- SE = 7.3 +/- 3.8 marks/10 min). From days 14 to 30 postcoitus chinning gradually rose in the pseudopregnant Ss (mean +/- SE = 12.7 +/- 5.4 marks/10 min) while remaining low in the pregnant ones (mean +/- SE = 2.6 +/- 1.9 marks/10 min). Parturition allowed a gradual rise in chinning scores. In Experiment 2 the same Ss were explored across a second reproductive cycle that included lactation. In contrast to Experiment 1, no significant variations in chinning were displayed along estrus, Ss showing high chinning scores already on the first day of observation (mean +/- SE from 12 days = 19.2 +/- 6.7 marks/10 min). In agreement with Experiment 1, mating drastically reduced chinning scores. Low levels were maintained throughout pregnancy (mean +/- SE = 3.4 +/- 2.4 marks/10 min) and lactation (mean +/- SE = 3.3 +/- 4.8 marks/10 min). Weaning allowed a gradual increase in chinning scores.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Chin-marking behavior in male and female New Zealand rabbits: onset, development, and activation by steroids.

Chin marking (chinning) frequency was determined daily in 25 male and 24 female New Zealand rabbits aged 31-150 days. Chinning appeared earlier in females (mean +/- SD = 41 +/- 16 days) than in males (47 +/- 13 days). Between days 30-50, females displayed chinning more frequently than males. Thereafter, chinning increased steadily in both sexes up to day 100. Chinning curves levelled on days 100 and 140 in males and females, respectively. Profile analysis of male and female chinning curves showed significant differences in their slopes and in their population means (p < 0.001). At 7 months of age (days 210-224), both sexes displayed adult chinning frequencies: mean of means +/- SD = 103 +/- 18 and 79 +/- 14 marks/10 min in males (n = 8) and females (n = 8), respectively. The administration of testosterone propionate (TP, 1 mg/day) or estradiol benzoate (EB, 1 microgram/day) to males and females, respectively, from days 31-50, stimulated higher chinning frequencies than those displayed by untreated animals. Results suggest that chinning frequency increases throughout development largely as a consequence of a concomitant increase in sex steroid secretion.

Aging↗

PubMed1979

The human chin and its relationship to mandibular morphology.

This study evaluated the proportion of the external chin (protuberantia mentalia) in relation to the total symphyseal area in normal jaws and those with a diverse morphology. A sample of 60 cases was randomly selected and divided into three groups of 20 each on the basis of normal growth, horizontal growth and vertical growth with an open bite. Tracings of lateral dn frontal radiographs were used to describe general mandibular form and to determine the percentage of external/total symphyseal area. Dental casts were also examined to determine a basal arch form ratio. The results of this study indicate that the amount of bony chin present is related to certain morphologic features of the mandible. The most significant findings illustrate: 1. The chin increases in size as the mandibular type varies from a vertical type, to a normal type, to a horizontal type of growth pattern. 2. With dental "hypofunction" in combination with an exaggerated vertical development of the mandible, a smaller proportion of the protruding chin is present. 3. The chin increases in size as the mandibular basal arch form varies from a tapered shape for the vertical cases to a more square form in the horizontal cases. 4. The degree of lateral ramal flair does not appear to influence the proportion of protruding chin present. Several models have been presented which attempt to explain protuberantia mentalia variation. The evidence in this study supports the concept that mandibular morphology is the result of the action of compensative adaption in a developing structure. There appears to be an implied polygenic influence on symphyseal morphology operating from the cartilaginous cranial base and mandibular basilar bone. This may be manifested in the relative proportion of mandibular basal bone to cranial base width, and to the vector of cranial base growth. The ultimate proportion of the bony chin is viewed to be the result of mandibular adaption to a functional musculoskeletal balance in the craniofacial complex. The extreme variability of chin form in man may be considered to be the result of compensative growth developing in response to the most structurally efficient jaw form, the contiguous soft and hard tissue environment, and the intrinsic genotype of the mandible.

Adolescent↗

PubMed1992

The ptotic (witch's) chin deformity: an excisional approach.

Ptosis of the chin pad is common and can be seen in patients of all ages. It may be associated with too little or (at times) too much anterior chin projection. Often there is an associated deep submental skin crease present. Frequently, the primary concern of the patient is the appearance or exaggeration of chin ptosis in smiling ("dynamic" ptosis). This report describes a flexible approach to the correction of developmental (and some iatrogenic) ptotic chin deformities. The key element in the approach is the direct excision of sagging or excess chin fat, muscle, and skin. No attempt is made to reposition or lift ptosis-prone soft tissues. If a deep submental skin crease is present, it too is excised. If the chin needs added anterior projection, it is accomplished with a stable alloplastic chin implant. The approach is uniquely suited to correct anterior overprojection caused by an excess of soft tissue at the front of the chin and has been successful in correcting the "dynamic" ptosis that appears with smiling.

Adult↗

PubMed1991

Pediatric chin injury: occult condylar fractures of the mandible.

The diagnosis of occult mandibular condylar fractures in children is often missed or delayed on initial examination when children present with a laceration to the chin. A clue to the diagnosis of this type of skeletal injury to the mandible is the knowledge of a commonly occurring pattern of injury associated with chin trauma. Chin laceration, fracture of the parasymphyseal region near the chin, and fracture of the condyles are often concomitant injuries of the mandible. This article reviews three case reports of children who sustained a chin laceration, fracture in the region near the chin, and fracture to the mandibular condyles secondary to chin trauma that were not initially diagnosed on clinical examination.

Child↗

PubMed1992

Chin position in profile analysis. Comparison of techniques and introduction of the lower facial triangle.

Many patients undergoing rhinoplasty can benefit from chin augmentation, yielding a more balanced appearance. Preoperative facial analysis identifies patients with retrusive chins and suggests optimal chin position. Current profile analysis methods depend on subnasale position (Legan's angle) or require estimation of bony landmarks from soft-tissue photographs (Goode's alar crease perpendicular, Gonzalez-Ulloa's zero meridian, and Merrifield's Z-angle). We describe a technique for determining ideal chin position using soft-tissue landmarks. We compare this technique with Legan's, Goode's, Gonzalez-Ulloa's, and Merrifield's techniques in 35 women and conclude that this method provides accurate and rapid determination of ideal chin position.

Adult↗

PubMed1991

[Reflex response of the masseter muscle after percussion of the chin and electrical stimulation of the upper lip in patients with central motor disorders].

In 23 patients with central motor disorders (spastic hemiparesis, pseudobulbar syndrome and parkinsonism) reflex responses in both masseters were evoked during their relaxation and contraction by percussion with a reflex hammer on the chin and by electric stimulation of the upper lip. For recording of the reflex responses the electromyographic method was used. On the side of the spastic hemiparesis, as compared with the finding on the non-paretic side, the author found changes in the short-, medium and late-latency excitation and inhibition segments of the reflex response. In patients with parkinsonism the medium-latency portion of the reflex response after percussion of the chin from above as well as from below was satisfactory. The late latency excitation response after percussion of the chin from below was greater than its corresponding part evoked by percussion of the chin from above. In patients with the pseudobulbar syndrome the inhibitory parts of the reflex responses after percussion of the chin were weak. The results of the examination provided thus more detailed information on disorders of supranuclear control of masseter muscles.

Cerebrovascular Disorders↗

PubMed1990

Horizontal-T genioplasty--(a modified technique for the broad or asymmetrical chin).

A modified technique for genioplasty is described. A horizontal, single-slice of bone is sectioned from the inferior border of the chin, with preservation of the lingual soft tissue attachment, in the conventional manner. This is divided sagittally into three segments, which are not necessarily equal, and are then repositioned in the shape of a horizontal 'T'. To achieve this, the lateral segments are advanced and approximated in front of the central fragment which itself is also advanced. These are fixed in position and when desirable any voids may be filled with autogenous bone or hydroxyapatite. This simple technique augments the chin to an equal if not to a greater extent than the conventional 'double slide' genioplasty. It combines augmentation with narrowing and has the flexibility to reposition the chin. This technique is not advocated for routine use but more for the special case when augmentation is required for the patient with a broad, flat or asymmetrical chin. A presentation of four case histories will illustrate the application of this technique.

Adolescent↗

PubMed1991

A surgical system for the correction of bony chin deformity.

Because the chin, like the nose, occupies a prominent position in the face, it must also be assessed in planning any changes in the facial profile. For example, a large nose associated with a microgenia does not appear as large when the chin is augmented. A chin increased in the vertical dimension confers an excessively long appearance to the face. Finally, a microgenia is associated with the stereotype of a sluggish personality, and a large chin in women connotes a masculine personality. The authors provide guidelines for assessing these variables and including them in surgical plan.

Chin↗

PubMed1991

[Burkitt's type ALL with numb chin syndrome as an initial manifestation].

A case of Burkitt's type ALL with numb chin syndrome as the initial manifestation is described. A 57-year-old Japanese male was admitted to our hospital in November 14, 1989 because of paresthesia at the chin and lower lip with diplopia and ptosis. Neurological examination revealed oculomotor paralysis of the right side and hypesthesia on the chin, lower lip and buccal mucous membrane. Laboratory findings showed increased leukocyte count. Bone marrow aspirate revealed hypercellular marrow with 92.3% leukemic cells which had vacuoles in the cytoplasm and surface marker of IgM, kappa type. The abnormalities of karyotype included t(8;14). He was treated with chemotherapy and radiation. His conditions were temporarily improved, but relapsed later and died in March 6, 1990. Leukemic infiltrations to the trigeminal nerve were found in autopsy. The relationship between lymphoid malignancies and numb chin syndrome was discussed.

Burkitt Lymphoma↗

PubMed1991

[Reflex response in the masseter muscle after tapping the chin in healthy persons--an electromyographic study].

In a group of healthy subjects the author evoked reflex responses in both masseters by percussion of the chin with a reflex hammer. The reflexes were evoked during relaxation, slight or intense contraction of the masseters with the mouth open or closed. By percussion of the chin from above extension reflexes were evoked and by percussion of the chin from below contracting reflexes. The response was recorded by means of an electromyographic apparatus. The short-term stretch responses were evoked from the relaxed and slightly contracted masseters with the mouth open or closed. During intense contraction of the masseters the short-latency reflex stretch response was not evoked. In that case at first a short-latency inhibition of the basal activity of the masseter was observed followed by a medium and late-latency excitation response. With the masseters relaxed a long-latency stretch response was observed only with the mouth open. Percussion of the chin from beneath with slight contraction of the masseter caused initial inhibition of its basal activity followed then by a short-latency excitation response. Based on the assembled results the author analyzed the mechanism of the reflex control of the masseters.

Chin↗

PubMed1991

Bone resorption, stability, and soft-tissue changes following large chin advancements.

Large advancement genioplasties were performed in 10 patients (mean advancement, 11.7 mm) by horizontal osteotomy of the inferior border of the mandible, with preservation of a musculoperiosteal pedicle to the advanced genial segment. Preoperative, immediate postoperative, and long-term follow-up lateral cephalometric radiographs were retrospectively analyzed to evaluate the osseous and soft-tissue changes of the chin. After a mean follow-up period of 15 months, 76% of the initial advancement was preserved, representing 24% osseous resorption. The enveloping soft tissues of the chin followed the bony movement in a ratio of 1:0.88. Horizontal osteotomy of the inferior border of the mandible was a relatively stable procedure when used for large chin advancements. The broadcast possible musculoperiosteal pedicle should remain attached to the advanced genial segment to minimize osseous resorption and to achieve more predictable soft-tissue changes.

Adolescent↗

PubMed1991

Reconstruction of the lower lip and chin with the composite radial forearm-palmaris longus free flap.

Four cases of total lip and chin reconstruction are presented. In three, the composite radial forearm-palmaris longus free flap was used for reconstruction. In the fourth case, the palmaris longus was separated from the flap but still used as a lower lip sling. In all cases, the entire lower lip and the soft tissue of the chin were reconstructed in one stage. All patients healed primarily, and the three who underwent radiotherapy tolerated it without complications. Lip seal and speech were good, and there was no problem with drooling. Postoperative results emphasize the importance of respecting the aesthetic unit of the lower lip and chin.

Adult↗

PubMed1991

Trembling chin--a report of this inheritable dominant character in a four-generation Canadian family.

Trembling chin is an unusual, benign, dominant trait. We describe the condition in a four-generation Canadian family. Investigations, which included E.E.G., electromyograph and facial nerve conductance studies on affected and unaffected individuals, were normal. Premature hearing loss, present in all affected members of this family over age 50, strongly suggests an association of trembling chin with otosclerosis. The merits of early diagnosis and preventive treatment for otosclerosis in persons affected by trembling chin are discussed.

Canada↗

PubMed1992

Densitometric evaluation of changes in the soft tissue of the chin and the lower lip during the treatment of Class III malocclusion.

The aim of this study was to use densitometry of lateral skull teleradiographs to evaluate the changes that occurred in the lower lip and chin after orthodontic or orthodontic-surgical treatment of Class III malocclusion. Forty teleradiographs from 20 patients with mandibular prognathism were made at the beginning and end of treatment. In ten of these patients the treatment was exclusively orthodontic with an edgewise appliance, and in another ten the treatment was orthodontic with a straight wire appliance combined with orthognathic and mentoplastic surgery. In the patients who were only treated orthodontically, a significant increase in density of the lower lip and the chin was found after treatment. This seemed to be related to an increase of muscular tension in these areas. Patients treated with orthognathic surgery and the straight wire appliance showed a decrease in density of the chin after treatment, but not of the lip. This can be interpreted as a consequence of muscular normalization after this procedure was accomplished.

Absorptiometry, Photon↗

PubMed1990

Numb chin syndrome: a case report.

Neuropathy of the inferior alveolar nerve is common in dental practice. Its cause, when not a result of local anesthetic, is normally from dental disease or trauma. Isolated mental neuropathy (numb chin syndrome) is extremely uncommon, and its most common cause also is dental. The next most common cause is from an underlying neoplasm, and some cases have resulted from systemic disease (eg, multiple sclerosis). Some patients show no evidence of additional disease and experience spontaneous remission of the symptom. Numb chin syndrome cases require coordination of treatment between dentists and physicians. Since a disproportionate number of these cases present with a numb chin as the first symptom of a neoplasm, aggressive diagnosis is required. Careful follow up is important before dismissing it as a spontaneous remission. Dentists must be familiar with isolated mental neuropathy and its medical implications because they are likely to be the first health professionals that patients present to for diagnosis.

Adult↗

PubMed1991

Chin rub CRs may reflect conditioned sickness elicited by a lithium-paired sucrose solution.

Rats were given a single conditioning trial in which 20% sucrose solution was paired with an intraperitoneal (IP) injection of lithium chloride (127.2 mg/kg), d-amphetamine (3 mg/kg) or physiological saline. Thirty min before a subsequent 10-min taste reactivity (TR) test and a 1-h conditioned taste avoidance (CTA) test the rats were injected IP with either the antiemetic agent, trimethobenzamide (5 mg/kg) [corrected] or with physiological saline solution. The lithium-paired, but not the amphetamine- or saline-paired, sucrose solution elicited the aversive TR responses of chin rubs, paw pushes and gapes. Trimethobenzamide suppressed the aversive TR response of chin rubs in the lithium-conditioned group, but not in a group given unconditionally aversive quinine solution. The CTA test was not sensitive to the antiemetic properties of trimethobenzamide, although the drug enhanced sucrose preference overall. The results suggest that chin rub responses may measure conditioned sickness.

Animals↗