a comparative study of temporomandibular symptoms following mandibular advancement by bilateral...

A comparative study of temporomandibular symptoms following mandibular advancement by bilateral sagittal split osteotomies: Rigid versus nonrigid fixation Brent Flynn, DDS, MS,a David T. Brown, DDS, MS,b Thomas H. Lapp, DDS, MS,’ David A. Bussard, DDS, MS,c and W. Eugene Roberts, DDS, PhD,d Indianapolis, Ind.

INDIANA UNIVERSITY, SCHOOL OF DENTISTRY

Rigid fixation to attach proximal and distal segments during bony healing of osteotomy sites has become increasingly popular. The effects of rigid fixation on the temporomandibular joints have been questioned. The purpose of this study was to evaluate the effects of rigid fixation after bilateral sagittal split osteotomies on temporomandibular dysfunction symptoms. Forty patients who had mandibular advancement surgery were evaluated for temporomandibular joint dysfunction. Twenty had received rigid fixation, and twenty had received nonrigid fixation. It was determined that there was no statistically significant difference in temporomandibular signs or symptoms between patients who were treated with rigid internal fixation for bilateral sagittal split osteotomies for mandibular advancement and those patients who were treated with nonrigid wire fixation. (ORALSURGORALMEDORAL P~~~0~1990;70:372-80)

I t has been estimated that 5% of American people have skeletal mandibular deficiencies. Twenty percent of these are severe enough to warrant surgical mandibular advancement, which means that more than 2 million Americans could potentially benefit from mandibular advancement.’

Surgical correction of mandibular deficiency has been used for the past 150 years. In 1849 Hullihen2 described an intraoral mandibular body osteotomy. Since then, there’have been many modifications in the technique used to advance the mandible.3-12 Surgeons continue to develop easier techniques that yield more predictable results.

Bilateral sagittal splitting of the mandible has evolved as the most popular procedure used to advance the mandible for correction of mandibular retrognathism. For many years the primary method that

aPrivate Practice Orthodontics, Mesa, Arizona. bAssistant Professor, Department of Prosthodontics. CPrivate Practice, Oral and Maxillofacial Surgery, Indianapolis. dProfessor and Chairman, Department of Orthodontics. 7/O/20298

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was employed to stabilize the advanced distal segment was the use of intraosseous fixation wires.‘3-*7 This form of segment stabilization has been called “nonrigid” fixation because the segments are not rigidly attached to each other during healing of the osteotomy site. Recently, many oral surgeons have used screws that rigidly attach the bony segments during healing of the osteotomy site. This technique has been called “rigid fixation” and seems to be increasing in popularity. With its increasing use, there has been considerable concern about the possible adverse effects of rigid fixation on the temporomandibular joints and subsequent development of temporomandibular disorder symptoms. Because temporomandibular dysfunction has been associated with the position of the condyle in the fossa, and because the use of rigid fixation may influence this position, the concern seems valid.

In 1988 Bloomquist18 reported that 62% of the patients who experienced temporomandibular symptoms before rigid fixation mandibular advancement surgery improved after surgery. He found that 15% reported no change, and 20% reported that their con-

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Temporomandibular symptoms after mandibular advancement 373

TMJ Evaluation

Patient Number: Date of Evaluation:

1.) Have you ever had any injury in the head and neck area? Yes No Describe

2.) Have you ever had any surgery in the head and neck other than orthognathic surgery? Yes No Describe

3.) Do you clench or grind your teeth? Yes No [sleeping, under stress, other J 4.) Do your jaw muscles ever feel tired? Yes No When 5.) Do you ever hear clicking or grinding sounds in your jaw joint? Yes No

Right Left Since When? During what activity Clicking Grinding

6.) Have your jaws ever “locked” closed? Yes No Describe 7.) Have your jaws ever “locked” wide open? Yes No Describe 8.) Do you ever have pain in your jaw joint? Yes No Describe

Since when? During what activity? Describe the nature of pain What increases the pain? What decreases the pain

9.) Does it hurt to chew Yes No Where 10.) Have you ever been treated for TMJ symptoms? Yes No Describe

What was the diagnosis? Clinical b

1.) Classification: Class I Class II Div. 1 Class II Div. II Class III 2.) Protrusive excursion: None Right Left Limited Complete 3.) Maximum mandibular opening: mm Pain

Overbite mm Total Opening mm 4.) Deviation from the midline upon opening: None Left Right 5.) TMJ Auscultation:

Right: Negative Condylar Subluxation Crepitus [Mild Severe] Clicking: Opening Closing Reciprocal

---mm -mm Left: Negative Condylar Subluxation Crepitus [Mild Severe]

Clicking: Opening Closing Reciprocal -mm -mm

6.) Muscle palpation: Right: Masseter Temporalis Lat. Pterygoid Med. Pterygoid Left: Masseter Temporalis Lat. Pterygoid Med. Pterygoid Other:

7.) TMJ palpation: Right: Negative Tenderness External Closed Own Internal Left: Negative Tenderness External Closed Open Internal

Fig. 1. Temporomandibular joint (TMJ) history and examination form used for the patient evaluations.

dition worsened. Twenty-two percent who reported no joint “popping” before surgery experienced it after surgery. Thirteen percent of the previously asymp- tomatic patients experienced temporomandibular joint pain after surgery. Karabouta and Martis19 studied 280 patients, all of whom were treated with sagittal split osteotomies. Before surgery, 40.8% had temporomandibular symptoms. After surgery, 11 .l% had signs of temporomandibular dysfunction according to the same index.

Will et al.*O studied condylar position after bilateral sagittal osteotomies with nonrigid fixation. They found a superior repositioning of the condyles along

with a counterclockwise rotation of the mandible during fixation. They found no changes in condylar position after release of fixation. Using computerized tomography, Spiker et al. *l studied positional changes of the condyle after sagittal split osteotomies of the ramus with rigid fixation. They found no major mal- positioning of the condyle-bearing fragments.

Recently, Buckley et al.** compared the complications that arose after wire fixation and after rigid fixation. They found no difference in occlusal results, surgical complications, joint pain, or range of motion.

According to the literature, 12% to 87% of Amer- ican people have some sign of temporomandibular

374 Flynn et al. ORAL SLKG ORAL MED ORAL PATH~L September 1990

Table I. Rigid fixation group ---

Patient Age Year.5 srnce 1 No. lvri Sex .surger.l: Clench/grind “Tired jaws” Hear click One side Both sides

I 25 F 4.00 I I I I 0 2 18 F 2.17 0 1 0 0 0

3 40 F 5.50 0 0 0 0 0 4 42 F 1.83 0 0 0 0 0 5 47 M 2.00 0 0 0 0 0 6 30 F 2.83 I 1 I 0 I 7 18 F I .75 0 1 0 0 0 8 18 M 2.17 0 1 I 1 0 9 20 F I .oo I 1 I 0 I

10 25 F 1.42 0 0 0 0 0 11 42 F I .I5 0 0 0 0 0 12 24 M 2.00 0 0 0 0 0 13 42 M 2.50 I 0 0 0 0 14 23 M 1.08 I 1 1 0 I 15 I8 F 1.75 0 0 0 0 0 16 18 M I .oo 0 0 0 0 0 17 28 F 1.33 1 1 1 I 0 18 19 F 2.17 0 0 0 0 0 19 44 F 2.33 0 0 0 0 0 20 25 F I .50 0 0 0 0 TOTALS 28 Mean = 2.1 6 i

0 6 3 5

Rigid fixation patient data include: number assigned to each patient, age, sex, time elapsed between surgery and clinical examination, and the number of positive responses in each category.

joint dysfunction. 23-29 These studies documented that the prevalence of temporomandibular joint sounds ranged from 14% to 39%, that the prevalence of joint sounds ranged from 28% to 53%, and that the prevalence of temporomandibular pain ranged from 2% to 11%. Muscular pain prevalence ranged from 15% to 56%. The average maximum interincisal opening varied from 43 to 56 mm.

The purpose of this study was to determine and compare the prevalence of temporomandibular symptoms in patients who have undergone mandibular advancement surgery with either rigid internal screw or nonrigid wire fixation.

MATERIAL AND METHODS Design of study

A cross-sectional epidemiologic study was performed on 40 patients who had undergone bilateral sagittal ramus osteotomies for mandibular advancement as described by Epker.5 All patients were from the same oral and maxillofacial surgery practice. At the time of surgery, acrylic resin interocclusal splints were used to establish the occlusion. Maxillomandib- ular fixation was applied and the condyle was gently seated in the fossa before the proximal and distal segments were secured with either rigid or nonrigid fixation.

Twenty patients had the proximal and distal bone segments secured with inferior border wires in a nonrigid fashion similar to techniques described by

Booth14 and by Smith, Moloney, and West. I5 Maxil- lomandibular fixation was maintained in these patients for 6 to 8 weeks with a combination of interdental and anterior skeletal fixation. The other 20 patients had the proximal and distal bone segments secured by 2.0 mm diameter bone screws. Two screws were placed on each side, avoiding the neurovascular bundle. At completion of the rigid fixation procedure, maxillomandibular fixation was terminated and mandibular rotation and occlusion were checked. If these were satisfactory, interdental maxillomandibular fixation was maintained in the patient for approximately 2 weeks.

The guidelines required to meet the criteria for this study included the following: (1) patients were male or female, 18 to 45 years of age; (2) there was a retrognathic relationship of the mandible to the maxilla before surgery; (3) no concomitant surgical procedures had been performed with mandibular advancement surgery; (4) the surgery had been within the last 5 years; (5) it had been at least 1 year since surgery; (6) orthodontic appliances had been removed before evaluation; and (7) there was a full or nearly full complement of posterior teeth. All patients were evaluated once with the same history and examination form (Fig. 1).

Each patient was asked several questions about the history of his or her temporomandibular joints. The patients were then clinically evaluated to determine: (1) occlusal classification, (2) maximal protrusive

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Table II. Nonrigid fixation group


Patient Age Years since No. fY4 Sex surgery Clench/grind “Tired jaws” Hear click One side Both sides

1 19 F 2.67 0 0 1 1 0 2 18 F 3.00 1 1 1 1 0 3 33 F 5.00 0 0 1 1 0 4 35 F 4.00 1 ! 0 0 0 5 30 F 3.00 0 1 0 0 0 6 18 F 4.75 0 0 0 0 0 7 23 F 4.08 0 0 0 0 0 8 18 M 2.50 0 0 0 0 0 9 18 M 4.17 0 1 1 0 1

10 32 F 5.33 0 1 1 1 0 11 21 F 5.00 0 0 0 0 0 12 22 M 4.75 0 0 0 0 0 13 29 M 3.42 0 1 0 0 0 14 27 M 4.50 0 0 0 0 0 15 29 F 1.75 1 1 1 0 1 16 44 F 4.42 0 0 0 0 0 17 27 M 4.42 0 0 0 0 0 18 26 F 4.17 0 1 1 1 0 19 18 F 3.50 0 0 0 0 0

20 44 F 2.33 0 TOTALS 27 Mean = 3.8 5

0 0 0 1! 8 7 5 2

Nonrigid fixation patient data include: number assigned to each patient, age, sex, time elapsed between surgery and clinical examination, and the number of positive responses in each category.

Table III. Statistical summary of patients’ age, sex, and postoperative time

Sex Age W Postoperative time (yr)

Group n (mean f SD) Male Female (mean + SD) .

Rigid 20 28 + 10.4 6 14 2.1 2 1.1 Nonrigid 20 27 + 8.2 6 14 3.8 + 1.0

movement, (3) maximum opening, (4) presence or absence of mandibular deviation on opening, (5) abnormal temporomandibular joint sounds, (6) muscle tenderness, and (7) temporomandibular joint tenderness.

During temporomandibular joint auscultation, a stethoscope was placed just anterior to the tragus of both ears while the participant opened and closed his or her mouth. The examiner also palpated the muscles of mastication. This involved: (1) the masseter muscle, palpated extraorally in the area of the angle of the mandible, (2) the temporal muscle, palpated ex- traor:Jly in the temporal region of the head, (3) the lateral pterygoid muscle, palpated intraorally just distal, lateral, and superior to the maxillary tuberos- ity, and (4) the medial pterygoid muscle, palpated extraorally behind the angle of the mandible and intraorally at the posterior and inferior depth5 of the lingual sulcus of the mandible. The temporomandibular joint was palpated extraorally. The clinical evaluation of all participants was performed by the same examiner.

Statistical analysis

The study population was divided into two groups according to the type of fixation that was used to stabilize the proximal and distal segments of the mandible. The results from each group were compared to determine if there was a difference in the prevalence of temporomandibular symptoms among them. The data collected in this study were nonparametric, ex- cept for questions 1 and 2 under the “Clinical Exam” section. The number of patients that answered “yes” to each question was recorded for each group.

The number of patients in each category was calculated. The results from the rigid and nonrigid fixation samples were then compared. To eliminate examiner bias, the examiner did not know the method of bone fixation that was used until after the evaluation. Participants were eliminated from the study if they failed to meet the criteria for the population or if they chose not to participate in the study.

A chi-square analysis was employed for all nonparametric data and a two-tailed standard t test was used for the parametric data.

376 Flynn et al. ORAL SLRG OR.AL bltl> ORAL PATHOL September 1990

Pain when chewing

Pain in jaw joint Nonrigid

Jaw has locked closed

c

1 Rigid Jaw had locked open

0 2 4 6 8

Number of Patients

Fig. 2. The number of patients in the rigid and nonrigid groups who reported a history of each type of symptom.

Maximal opening.

Nonrigid

n Rigid

i . , , ” I

0 10 20 30 40 50 60

Millimeters

Fig. 3. Mean maximal opening and protrusive move- ments for the rigid and nonrigid groups.

RESULTS

Forty white persons participated in this study. Twelve participants were men and 28 were women. There were six men and 14 women in each group (Tables I and II). The average age of all participants at the time of surgery was 27.5 years. A summary comparison of the age, sex, and postoperative time of the two groups is found in Table III.

The average time that had elapsed between surgery and the date of the evaluation was 3 years. In the rigid group, the mean time since surgery was 2 years 1 month, with a range of 1 year to 5 years 6 months. In the nonrigid group, the mean time since surgery was 3 years 10 months, with a range of 1 year 9 months to 5 years 4 months.

The results of the dental history questions are presented on a bar graph in which the number of patients is plotted against each type of symptom (Fig. 2). Seven participants responded positively to the question, “Does it hurt to chew?” In the rigid group, three responded positively, one man and two women. In the nonrigid group, four responded positively, two men and two women.

Eight participants reported that they had postop-

Sensitive TMJ

Sensitive medial pter.

Sensitive lateral pter.

Sensitive temporalis

Sensitive masseter

Deviation on opening

Crepitus

Nonrigid

n Rigid

0 2 4 6 8 10

Number of Patients

Fig. 4. The number of patients in the rigid and nonrigid groups who clinically demonstrated symptoms of temporomandibular disorders.

erative pain in their jaw joints. In the rigid group, five participants reported pain, three men and two women. In the nonrigid group, three participants reported pain, all of whom were women. Three participants reported that their jaws had locked open at least once since surgery. None of the participants reported that their jaws had locked closed. In the rigid group, two participants reported that their jaws had locked open, one man and one woman. In the nonrigid group only one woman reported locking. Two participants were aware of grinding sounds in their jaw joints. Both of those patients were members of the rigid group, one man and one woman. Thirteen participants were aware of clicking sounds in their jaw joints. In the rigid group, six participants were aware of clicking sounds, two men and four women. In the nonrigid group, seven participants were aware of clicking sounds, one man and six women. Sixteen participants responded positively to the question, “Do your jaw muscles ever feel tired?” In the rigid group, eight participants responded positively, two men and six women. In the nonrigid group, eight participants responded positively, two men and six women, Nine participants reported postoperative clenching or grinding. In the rigid group, six participants reported clenching or grinding, two men and four women. In the nonrigid group, three women reported clenching or grinding.

The mean amounts of maximal mandibular opening and maximal protrusion for both groups are shown in Fig. 3. The average maximal mandibular opening measured interincisally was 43.5 mm with a range of 30 to 60 mm. In the rigid group, the mean opening was 43.8 mm with a range of 30 to 60 mm and a standard deviation of 7.21 mm. In the nonrigid group, the mean maximal interincisal opening was 43.2 mm with a range of 31 to 50 mm and a standard deviation of 4.7

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Table IV. Statistical summary of historical data including the number of patients with each sign or symptom, confidence levels, and significance

Patient history

Clench/grind “Tired jaws” Clicking sound Grinding sound Locked open Locked closed Joint pain Chewing pain

No. patients with symptoms

Rigid Nonrigid

6 3 8 8 6 7 2 0 2 5 0 0 5 3 3 4

Confidence level (%!

70-80 -3

20-30 SO-90 30-50

<5 50-70 30-50

SigniJicance

0.2 < p < 0.3 p > 0.95

0.7 < p < 0.8 0.1 <p IO.2 0.5 < p zz 0.7

p > 0.95 0.3 < p 5 0.5 0.5 < p 5 0.7

Table V. Statistical summary of clinical data including the number of patients with each sign or symptom, confidence levels, and significance

Clinical examination

Midline deviation Clicking Crepitus Sensitive Masseter Temporalis Lateral pterygoid Medial pterygoid TMJ Max. protrusion Max. opening

No. patients with symptoms

Rigid Nonrigid

1 2 6 6 2 2

0 1 1 1 1 2 1 0 4 1

*6.2 + 2.02 *6.35 k 1.63 *43.8 k 7.21 *43.2 f 4.70

Confidence level

(%1

30-50 <5 <5

50-70 <5

30-50 50-70 SO-90 60-62.5 60-62.5

Significance

0.5 < I p 0.7 p > 0.95 p > 0.95

0.3 < I p 0.5 p > 0.95

0.5 < I p 0.7 0.3 < 5 p 0.5 0.1 <p 5 0.2

0.375 < 5 p 0.4 0.375 < 5 p 0.4

Th4.f. Temporomandibular joint. *Mean c 1 SD.

mm. None of the participants reported pain during maximal opening. The average maximal protrusive mandibular movement was 6.28 mm with a range of 3 to 10 mm. In the rigid group, the mean protrusive movement was 6.2 mm with a range of 3 to 10 mm and a standard deviation of 2.02 mm. In the nonrigid group, the mean was 6.35 mm with a range of 4 to 10 mm and a standard deviation of 1.63 mm. None of the participants reported pain during protrusion.

The results of the clinical evaluation have been compared on a bar graph in which clinical symptoms are plotted against the number of patients who demonstrated symptoms of temporomandibular joint disorders (Fig. 4). Five patients reported tenderness on palpation of the temporomandibular joint. In the rigid group, four reported tenderness, two men and two women; and in the nonrigid group one man reported tenderness. Only one woman, from the rigid group, reported tenderness on palpation of the medial pterygoid muscles. Three patients reported tenderness on palpation of the lateral pterygoid muscles. One woman in the rigid group reported tenderness. In the nonrigid

group, two women reported tenderness. Two patients reported tenderness on palpation of the temporalis muscles, one woman from each group. Only one patient reported tenderness on palpation of the masseter muscles. This was a woman in the nonrigid group. Three participants were found to have a deviation of 2 mm or more from the midline on opening. This included one woman in the rigid group and one man and one woman in the nonrigid group. Two patients, one woman in the rigid group and one woman in the nonrigid group, were found to have articular crepitus during temporomandibular joint auscultation. Twelve patients were found to have a click during temporomandibular joint auscultation. In the rigid group, six participants demonstrated clicking sounds, three men and three women. In the nonrigid group, six participants demonstrated clicking sounds, one man and five women.

Statistical comparisons of historical and clinical data are presented in Tables IV and V. The results of this study indicate that there was no difference in the prevalence of temporomandibular symptoms between

378 Flynn et al. ORAL SURG ORAL MED ORAL PATHOL September 1990

patients who had received rigid internal fixation during bilateral sagittal split osteotomies for mandibular advancement and patients who had received nonrigid wire osteosynthesis for the same procedure.

DISCUSSION

This study was carried out to gain a better under- standing of the relationship between rigid internal fixation and the temporomandibular joint. Generally accepted “abnormal” temporomandibular findings 23-29 were evaluated in this study. These symptoms can be subjective in nature and must be viewed accordingly.

Symptoms based on patient history are subject to memory and interpretation based on the patient’s life experience. These symptoms have been referred to as “subjective temporomandibular findings.” They are, however, frequently reported in studies that attempt to quantify the prevalence of temporomandibular disorders.

It has been estimated that 12% to 87% of Ameri- can people have at least one sign of a temporomandibular disorder.23-29 In this study, 60% of the rigid group and 55% of the nonrigid group showed at least one sign of what may be considered abnormal temporomandibular joint function after surgery. These figures are based on both subjective and objective responses. When only clinically demonstrated symptoms are considered, 55% patients in the rigid group and 40% of patients in the nonrigid group were found to have at least one sign or symptom associated with temporomandibular disorders.

Thirty percent of the rigid group believed that they had experienced clenching or grinding of their teeth, whereas only 15% of the nonrigid group expressed the same finding. These figures may be compared to a previous study that showed that 10% of randomly selected patients were aware that they ground their teeth, and 20% were aware that they clenched their teeth.29

In this study, 40% of the patients in each group reported that their jaws “felt tired.” This is in contrast to 6% reported as normal in the literature.23-29 In the rigid group, 30% of the patients were aware of joint sounds in their jaws, and 35% in the nonrigid group were unaware of any jaw clicking or grinding. These figures may be compared to the 15% to 53% reported as normal in the literature.23-29

In the rigid group, 25% reported some form of postoperative pain, and 15% of the nonrigid group reported this finding. This is in contrast to 2% to 15% reported in the literature as norma1.23‘29 These findings vary greatly according to the definition of pain, (e.g., dull, sharp, throbbing, etc.). In this study, all types of pain have been grouped together, which would presumably increase the prevalence reported.

When asked, “Does it hurt to chew?“, 13% of the rigid group and 20% of the nonrigid group responded positively.

This study included a clinical evaluation that con- tained both objective and subjective findings. Direct linear measurement such as the maximal protrusive movement and maximal mandibular opening are objective and reproducible findings. The average amount that members of the rigid group could maximally protrude their mandibles was 6.2 mm, and the mean protrusive movement for the nonrigid group was 6.35 mm. This is comparable to 7 mm reported in the literature as normal.30

The mean maximal mandibular opening measured interincisally for the rigid group was 43.8 mm, and the mean maximal opening for the nonrigid group was 43.2 mm. This is comparable to 35.1 mm reported as average for postoperative bilateral sagittal split osteotomies.3’ This is also comparable to the 35 to 56 mm range reported in the literature as norma1.23-29 None of the participants in this study reported pain at maximal opening.

In the rigid group, 5% were found to have a mandibular opening deviation from the midline of 2 mm or more, and 10% of the nonrigid group had such a deviation. These findings are considerably less then the 34% reported in the literature as norma1.23 In both the rigid and nonrigid groups, 40% demonstrated clicking or articular crepitus sounds in the temporomandibular joint. This is comparable to the 11% to 65% range reported in the literature.23-29, 32

The subjective nature of the clinical evaluation involved the palpation of the muscles of mastication and the temporomandibular joint. The subjective nature of the interpretation of pain also plays a role because what may feel like pressure to one person, may be reported as pain by another. These subjective interpre- tations may be reflected in the wide range of prevalence reported in association with these symptoms. In clinically evaluating the patient sample for symptoms, the operator attempted to be consistent in palpating the muscles and the temporomandibular joint in similar locations and with consistent pressure.

Overall, 5% of the rigid group reported some pain on palpation of the muscles of mastication, and 15% of the nonrigid group reported the same. This is comparable to the range of 13% to 64% reported in the literature.23-29 Twenty percent of the rigid group reported pain on palpation of the temporomandibular joint in either the open- or the closed-jaw relationship, whereas only 5% of the nonrigid group reported pain. This is comparable to 39% reported in the literature.33

Although there are inherent flaws in comparing the prevalence of temporomandibular joint symptoms of patients who have had surgery to randomly selected patients from other studies who have not had surgery,

Volume 70 Temporomandibular symptoms after mandibular advancement 379 Number 3

it can be said that both the rigid and nonrigid sample groups of this study generally fall within the range of reported prevalence of “normal” populations. There was no significant difference in symptoms between the rigid and nonrigid fixation groups. However, the rigid group did show a trend toward an increased incidence of temporomandibular joint crepitus and temporomandibular joint tenderness palpation. A larger population would be helpful in determining whether this trend is significant. To date, there have been no large-scale studies that report the prevalence of these symptoms in true skeletal retrognathic patients. The findings of such a study would be a valuable aid with which to compare the results of this study. The prevalence of temporomandibular joint symptoms in a population of retrognathic patients who have not had surgery could be very similar to or very different from that found in “normal” populations.

To overcome the possibility that the prevalence of temporomandibular symptoms found in the group of patients who had undegone rigid fixation was different than the prevalence found among the group of nonrigid patients before their presurgical orthodontic phase, no patients who had been treated surgically for temporomandibular symptoms were admitted into this study. The basic thrust of this study was to determine whether rigid fixation used for bilateral sagittal- split osteotomies was more or less damaging to temporomandibular joint than nonrigid fixation.

SUMMARY AND CONCLUSIONS

Bilateral sagittal splitting of the mandible is a popular procedure used to advance the mandible and to correct mandibular retrognathism. For many years the primary method that was employed to stabilize the bone segments was fixation with intraosseous wires. This form of segment stabilization has been called “nonrigid” fixation because the proximal segments are not rigidly attached to the distal segment during healing of the osteotomy site.

Recently, many surgeons have used small bone screws to rigidly attach the proximal and distal segments during the bony healing of the osteotomy site. This type of segment stabilization has been termed “rigid fixation.” With the increased popularity of rigid fixation, concerns have been raised as to its ef- fect on the temporomandibular joint. This study was undertaken to evaluate the effects of rigid fixation on temporomandibular symptoms when used in bilateral sagittal split osteotomies for mandibular advancement. Forty patients who had undergone surgery for mandibular advancement were evaluated for symptoms related to temporomandibular disorders. Twenty had rigid fixation (screws) between the proximal and distal segments, and 20 had nonrigid fixation (wires).

Each patient was asked several questions about the

history of his or her temporomandibular joint. Each was then clinically evaluated for signs of temporomandibular disorders. Results of the rigid fixation group were calculated and compared with the results from the nonrigid group with chi-square analysis and the standard t test. It was determined that there was no difference in the prevalence of temporomandibular symptoms between patients who had received rigid internal fixation during bilateral sagittal split osteotomies for mandibular advancement and patients who had received nonrigid wire osteosynthesis for the same procedure.

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a comparative study of temporomandibular symptoms following mandibular advancement by bilateral...

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