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Biomedical subjects

D P Sinn

Publications and source records attributed to D P Sinn.

At least 19 recordsLinked to original sources
PubMed1996

Bite forces before and after surgical correction of mandibular prognathism.

PURPOSE: The purpose of this investigation was 1) to compare morphologic parameters and voluntary bite forces between controls and a sample of patients with mandibular prognathism before surgical correction, and 2) to examine how these patients' bite forces adapt after treatment. PATIENTS AND METHODS: Twenty-four prognathic patients were compared with 24 controls before and up to 3 years after mandibular setback surgery. Measures of skeletal morphology and maximum isometric bite force were made on all subjects over time. Statistical analysis compared the controls, the patients before surgery, and the patients after surgery. RESULTS: Surgical shortening of the mandible averaged 4.1 mm, bringing most skeletal measures into the normal range. Before surgery, the jaw muscle mechanical advantages for patients were significantly smaller than for controls; surgery did not significantly change this relationship. Before surgery the patients had maximum isometric bite forces that were significantly less than those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 to 3 years. CONCLUSIONS: The results of this study suggest that correction of mandibular prognathism by mandibular setback surgery produces some significant functional benefits.

Adolescent↗
PubMed1996

Functional and morphologic changes after combined maxillary intrusion and mandibular advancement surgery.

PURPOSE: The purposes of this investigation were 1) to compare the morphology and function of patients with combined vertical maxillary excess (VME) and mandibular retrognathia with that of controls, and 2) to examine how these parameters change after combined maxillary intrusion and mandibular advancement surgery. PATIENTS AND METHODS: Fifteen female VME/retrognathic patients were compared with 26 female controls before and for up to 3 years after orthognathic surgery. Facial skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyographic activity (EMG) in selected muscles of mastication were measured on all subjects. Where appropriate, one-way analysis of variance (ANOVA) or t-tests were used to compare the patients with controls. Univariate repeated-measures ANOVA was used to study longitudinal changes. RESULTS: Preoperatively, patients' morphologic measurements were characteristic of VME compounded by mandibular retrognathia. At surgery, the maxilla was elevated an average of 2.8 mm, and the mandible was lengthened by an average of 7.1 mm. All of the postoperative morphologic measurements were closer to normal values. The patients' masseter mechanical advantage was significantly lower than that of controls both before and after surgery. Surgically induced changes in mechanical advantage were very small. The patients' maximum range of motion and excursion during mastication were all lower than those of controls before surgery. All measurements of mobility decreased immediately after surgery, with a gradual return to preoperative values. However, even 3 years after surgery, all of the motion measurements remained smaller than those of the controls. Before surgery, the patients had maximum isometric bite forces significantly lower than those of controls. Bite forces increased significantly after surgery, approaching normal values within 2 years. The activity levels in the muscles of mastication during isometric bites were not significantly altered by surgery. CONCLUSIONS: This study confirms that VME/retrognathia patients suffer from substantial deficiencies in their oromotor function. Surgical correction of this particular type of dentofacial deformity improves both the morphologic and functional deficits. Although some changes were not statistically significant, all were toward normalization of the presurgical values.

Adolescent↗
PubMed1996

Mandibular excursions and maximum bite forces in patients with temporomandibular joint disorders.

PURPOSE: This study evaluated mandibular motion and bite force in patients with temporomandibular joint disorders after joint surgery. PATIENTS AND METHODS: Maximum voluntary mandibular motion, maximum excursion during mastication, and maximum bite force were examined in 25 female patients before temporomandibular joint surgery. Their pretreatment performance was compared with that at 6 weeks, 6 months, and 1 year after surgery, and with performance of 26 normal female volunteers. RESULTS: Before surgery, all of the patients' movements and bite forces were smaller than those of controls. One year after surgery, maximum interincisal opening increased significantly, but lateral excursion and protrusion remained unchanged. Maximum bite forces increased significantly and nearly reached control levels. CONCLUSIONS: Patients with severe restriction in temporomandibular joint function exhibit general improvements in some mandibular movements and in maximum bite force after surgical treatment.

Adolescent↗
PubMed1995

The effects of orthodontic treatment on isometric bite forces and mandibular motion in patients before orthognathic surgery.

PURPOSE: Little is known about the effects of orthodontic treatment on oral motor function. The objective of this report is to evaluate changes in mandibular motion and maximum bite force that occur between the initiation of presurgical orthodontics and its completion before surgery. PATIENTS AND METHODS: Fifteen patients (9 women, 6 men) with a variety of dentofacial deformities were examined before and after presurgical orthodontics. Mechanical advantage of the muscles and bite points, mandibular range of motion, maximum isometric bite force, and levels of electromyographic (EMG) activity in the anterior and posterior temporalis and masseter muscles during isometric bites were recorded on all subjects over time. Data obtained before and after completion of presurgical orthodontics were statistically compared. RESULTS: Presurgical orthodontics reduced mandibular mobility somewhat, but the amount was not significant. Statistically significant reductions in bite force were noted after orthodontics for incisor, canine, premolar, and molar bite positions. No significant difference in the EMG/bite force slopes was obtained, nor was there any difference in the moment arms of the bite points or the muscles of mastication from orthodontics. CONCLUSIONS: This study showed significant changes in measures of oral motor function resulting from orthodontic treatment. A larger study is needed to confirm that these results will be similar in all orthodontic patients. There is no indication that these changes are the result of physiologic alterations of the muscles of mastication. The best current explanation is that these changes result from the pain and discomfort of the orthodontic appliances and the induced malocclusion.

Adolescent↗
PubMed1995

Functional characteristics of retrognathic patients before and after mandibular advancement surgery.

PURPOSE: The purpose of this investigation was to compare morphologic parameters and functional performance between controls and a sample of patients with mandibular retrognathia prior to surgical correction, and to examine how oral motor function adapts after treatment. PATIENTS AND METHODS: Twenty-four retrognathic female patients were compared with 26 female controls before and up to 3 years after mandibular advancement surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyographic activity in the anterior and posterior temporalis and masseter muscles during isometric bites were made on all subjects over time. One-way analysis of variance was used to compare the controls, the patients before surgery, and the patients after surgery. RESULTS: Surgical lengthening of the mandible averaged 7.3 mm, bringing most skeletal measures into the normal range. There were no significant differences in jaw muscle mechanical advantage between patients and controls before surgery, but surgery significantly reduced mechanical advantage of the anterior temporalis and masseter muscles. Jaw hypomobility was apparent at 6 weeks after surgery, but returned to normal values within 12 to 24 months. Before surgery the patients had maximum isometric bite forces less than half those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite force were equivalent to those of controls or somewhat higher. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls. CONCLUSION: The results of this study suggest that correction of mandibular retrognathia by mandibular advancement surgery produces some significant functional benefits.

Adolescent↗
PubMed1995

A longitudinal study of changes in masticatory performance of patients undergoing orthognathic surgery.

PURPOSE: Individuals with developmental deformities of the jaws may be less efficient at chewing food. Previous studies have reported masticatory deficiency in patients with such deformities. This study was designed to detect any changes in masticatory performance that accompany orthognathic surgery. MATERIALS AND METHODS: Masticatory performance was tested in 18 patients with various jaw deformities before application of orthodontic appliances and 2 to 3 years after surgical correction of their malocclusion. A control group was tested at three 6-month intervals. The subjects chewed carrots and masticatory performance was measured using a standard sieve technique. The Rosin-Rammler equation was used to calculate the median particle size and broadness index of each set of carrots. The number of chewing cycles required for each subject to swallow one piece of carrot was also recorded. RESULTS: A statistically significant difference in median particle size between patients and controls was found both preoperatively and postoperatively (P < .05), but no difference in median particle size or broadness index was seen between trials for controls or patients (P > .05). CONCLUSION: It was concluded that before surgery patients have a lower level of performance than controls and surgical correction of the malocclusion does not significantly enhance performance.

Adolescent↗
PubMed1995

Functional and morphologic alterations secondary to superior repositioning of the maxilla.

PURPOSE: The purpose of this investigation was to 1) compare morphological characteristics and functional performance of a sample of patients with vertical maxillary excess (VME) with controls, and to 2) examine how the patients' oral motor function adapts to surgery. MATERIALS AND METHODS: Fifteen female VME patients were compared with 26 female controls before and up to 3 years after maxillary intrusion surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyogram (EMG) activity in some of the muscles of mastication were made on all subjects over time. One-way analysis of variance (ANOVA) was used to compare the controls with the patients before and after surgery. Univariate repeated measures ANOVA was used to study longitudinal changes in the patients. RESULTS: Preoperatively, the patients possessed morphological measurements characteristic of vertical maxillary excess. Superior repositioning of the maxilla averaged 3.3 mm. Concurrently, most skeletal measures were brought closer to normal values. Masseter muscle mechanical advantage was significantly lower in the patients than in controls both before and after surgery (P < or = .05). There was no significant difference between patients and controls for other biomechanical measurements. Mandibular hypomobility was apparent at 6 weeks after surgery, but returned to control values within 6 to 12 months. Before surgery, the patients had maximum isometric bite forces significantly less than those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite forces were equivalent to those of controls or somewhat lower. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls. CONCLUSIONS: The results of this study suggest that correction of vertical maxillary excess with maxillary intrusion surgery improves some characteristic functional deficits.

Adolescent↗
PubMed1994

Masticatory performance, muscle activity, and occlusal force in preorthognathic surgery patients.

Previous studies have indicated that patients scheduled for orthognathic surgery tend to have lower maximum bite forces and exert lower forces during mastication. The effect of these deficits on masticatory performance have not been previously assessed. Masticatory performance was analyzed in four groups: male and female orthognathic surgery patients prior to presurgical orthodontics (n = 12 and 23), and male and female controls (n = 27 and 31). Mastication performance was analyzed by having the subjects chew 5-g pieces of carrot for 20 cycles and measuring the resulting median particle size with a standard sieve method. Masticatory performance showed the same trends as maximum bite force and masticatory forces: male controls had the best and patients the poorest masticatory performance. There was a weak correlation between masticatory performance and maximum bite force at the molar positions. Masticatory performance also weakly correlated to electromyographic signals during mastication of a constant bolus (gummy bears) for all muscles except the left posterior temporalis. Correlations were generally not present or were very weak between masticatory performance, estimated masticatory forces, and muscle efficiency, suggesting that muscle efficiency and forces generated during mastication are not the primary factors that determine masticatory performance. Other factors contributing to a person's ability to chew food might include occlusal relationships and mechanical advantage.

Adolescent↗
PubMed1994

Estimated masticatory forces in patients before orthognathic surgery.

There has been relatively little study of masticatory forces in dentofacial deformity patients before orthognathic surgery. This study used a mathematical equation based on electromyographic activity (EMG) during mastication and forces obtained during isometric bites to estimate masticatory forces in 55 control subjects and 48 patients. Subjects chewed on a constant bolus while EMG recordings were made bilaterally from the superficial masseter, anterior temporalis, and posterior temporalis muscles. Unilateral isometric bite forces in the first molar position and simultaneous EMGs were recorded in these same subjects. Superficial masseter muscle activity and isometric bite forces were strongly correlated. The slope of masseter EMG versus isometric force was used to estimate the masticatory forces. Males were found to have significantly higher estimated masticatory forces than females.

Adult↗
PubMed1994

Connective tissue forces from mandibular advancement.

PURPOSE: To quantify the connective tissue forces generated during surgical lengthening of the mandible. PATIENTS AND METHODS: Sixty-three patients who had mandibular advancements by sagittal ramus osteotomy were used in this study. Prior to sectioning the rami, the overjet was recorded. After sectioning the rami, a spring-gauge was attached to the mandibular orthodontic wire and pulled anteriorly to determine how much force was necessary to bring the mandibular incisors into a Class I relationship with the maxillary incisors. Aggressive stripping of the perimandibular periosteum and connective tissues on the distal segment was then performed. The amount of force was again recorded. RESULTS: The mean preoperative overjet in the 63 patients was 6 mm (range, 3 to 11 mm). The mean amount of force required to advance the mandible prior to stripping the tissues was 1,498 g compared with a mean of 787 g after stripping (P < .001). There were statistically significant correlations between the preoperative overjet and the prestripping and poststripping force levels (P < .001). There was also a significant relationship between prestripping and poststripping values (P < .001). CONCLUSION: The results of this study indicate that orthopedic forces are generated by the perimandibular connective tissues following advancement by the mandible. The effect of these forces on the temporomandibular joint should be evaluated in future studies.

Bone Resorption↗
PubMed1993

Treatment of mandibular angle fractures using two 2.4-mm dynamic compression plates.

Sixty-five consecutive patients with fractures of the mandibular angle were treated by open reduction and internal fixation using two dynamic compression plates placed through a transoral incision using transbuccal trochar instrumentation and 2.4-mm screws. In the first 20 cases, the screws were inserted without tapping the drill holes. In the remaining 45 cases, the drill holes were tapped. No patient was placed into postsurgical maxillomandibular fixation or training elastics. Overall, 21 fractures (32%) developed infections requiring secondary surgical intervention. The infection rate was higher in those fractures where the holes were not tapped (40%) than those cases when the holes were tapped (29%). Of the 21 fractures that required hardware removal, 9 fractures were healed and required no further treatment; 12 had no firm bony union and required postsurgical maxillomandibular fixation. Only one case resulted in a malunion with resulting malocclusion. The use of two dynamic compression plates was found to be relatively easy, but resulted in an unacceptable rate of infection.

Adolescent↗
PubMed1993

Use of homologous bone in maxillofacial surgery.

Homologous bone grafts were used in 135 maxillofacial surgical procedures, including acute midfacial fracture repair (n = 77), elective osteotomies of the facial bones (n = 35), secondary correction of traumatic deformities (n = 6), mandibular reconstruction (n = 10), facial bone augmentation (n = 5), and reconstruction of maxillary tumor defects (n = 2). Postsurgical complications occurred in five of the patients. This article reviews the rationale for using homologous bone grafts, their immune response, how they heal, and the risk of transmission of disease.

Adolescent↗
PubMed1993

Complications of nonrigid fixation of mandibular angle fractures.

This retrospective study analyzed complications in 96 patients with 99 mandibular angle fractures treated during a 3-year period with either closed reduction or nonrigid means of fixation combined with maxillomandibular fixation. An overall complication rate of 17% occurred. Infection was the most common complication, occurring in 17 fractures. Thirteen fractures had infection as the only complication; in the remaining four patients, infection was combined with malunion/malocclusion. The results of this study show that mandibular angle fractures in an inner-city population are associated with a high incidence of postsurgical complications.

Adolescent↗
PubMed1993

Relationship of substance abuse to complications with mandibular fractures.

This retrospective study analyzed the relationship between complications and substance abuse following mandibular fracture. Over a 2-year period, the records of 352 patients with 589 mandibular fractures were reviewed for methods of treatment and other variables, including chronic abuse of drugs. An overall complication rate of 18.5% was found. Positive associations between complications and chronic abuse of alcohol and nonintravenous and intravenous drugs were found. Intravenous drug abusers had a 30%, nonintravenous drug abusers had a 19%, and chronic alcohol abusers had a 15.5% incidence of complications. Those individuals who did not use any drug chronically had a 6.2% complication rate. The results of this study show that chronic substance abuse can significantly affect treatment outcomes for management of mandibular fractures.

Adolescent↗
PubMed1992

A preliminary study of maximum voluntary bite force and jaw muscle efficiency in pre-orthognathic surgery patients.

The functional state of dentofacial deformity patients before orthognathic surgery has received relatively little study. In this study, the ability to generate occlusal force was compared between 84 patients before treatment for various dentofacial deformities and 57 controls. Maximal and submaximal bite forces were measured at the incisor and right and left first molar bite positions. Electromyographic activity (EMG) was recorded bilaterally from the anterior temporalis, posterior temporalis, and masseter muscles during each bite. An efficiency ratio was calculated for the jaw muscles by dividing the level of EMG by the occlusal force. There was a reduced ability to generate occlusal forces in the patients before surgery, especially among female patients. The reductions in maximal occlusal force were correlated with reduced efficiency of the jaw muscles.

Adult↗
PubMed1992

A retrospective study of advancement genioplasty using a special bone plate.

This study evaluates skeletal stability and the remodeling process of the advanced genial segment when a single bone plate is used to stabilize the segment following osteotomy of the inferior border of the mandible. Thirty-nine patients with a minimum of 6 months follow-up who had advancement genioplasty stabilized with a Paulus chin plate were analyzed using cephalometrics and clinical examination. The results showed that stability of the result was excellent; pogonion maintained its immediate postsurgical horizontal position at longest follow-up. The remodeling pattern observed was similar to that reported in other studies using alternate forms of fixation in spite of the fact that the bone plate covered the areas where most remodeling occurs.

Adolescent↗
PubMed1992

Advances in orthognathic surgery.

The basic treatment objectives in the management of patients with dentofacial deformities have remained unchanged. However, there have been significant advances in the evaluation and treatment planning of these patients. These advances can be divided into two major categories: the incorporation of concomitant or delayed adjunctive aesthetic procedures; and the treatment of select patients in an ambulatory setting. These advances have objectively improved postoperative results and patient comfort and have reduced the costs of traditional inpatient surgery. This article reviews the recent literature relative to both of these categories.

Ambulatory Surgical Procedures↗