chewing Movements in TMD Patients and a Control Una Soboieva, DDS, MSc^ Asbjorn ¡okstad. LDS, Dr Odont'' Group Before and After Use Thomas Eckersberg, LDS, MSc^ of a Stabilization Splint Bjorn L Dabi, LDS, Dr Odonfi

Purpose: This study assessed the effect of using an occlusal stabilization splint ¡n the maxilla for 6 weeks on certain parameters of chewing movements in subjects with and without temporomandibular disorder symptoms. Materials and Methods: Twelve male and 30 female temporomandibular disorder patients with and without a prior whiplash incidence, and individuals without signs and symptoms of temporomandibular disorders participated. The participants formed three groups matched according to gender and age (n = 3 x 14). A maxillary stabilization splint was used during sleep for 6 weeks. An optoelectronic system {iVlacReflex, Qualisys) was used to record chewing movements at baseline, before using the splint, and after 6-week5' use of fhe splint. Calculated parameters were fhe duration of the chewing cycles, the spatial displacement, and the mean velocity of the while chewing paraffin wax for 20 seconds. Results: On a group basis, the use of an occlusal stabilization splint for 6 weeks did not change the movement parameters in a predictable pattern as recorded under the conditions of this study. On an intraindividual basis, large variations in changes of chewing parameters over lime were observed. Conclusion: The use of an occlusal stabilization splint for 6 weeks did not alfer the jaw movements when chewing a substance with a soft consistency. Intj Prosthodont ¡998;n:l5S-164.

omplete-arch occlusal stabilizatiofi splints are from periodontal proprioceptors in relieved teeth.^ Ccommonly used in the management of patients Other investigators emphasize cognitive aware- with temporomandibular disortjers (TMD) with a re- ness'" or a probable placebo effect" caused by car- ported apparent effectiveness.^- However, the ther- rying foreign elements in the oral cavity. Another apeutic mechanism in the treatment of patients with hypothesis relates the apparent effectiveness to a such disorders remains uncertain.^'' Several hy- frequent contact with the therapist or entry into the potheses focus on eliminating or reducing the clinic environment.'^ In contrast, some investiga- daily^'^ or nocturnaF activities of the jaw muscles, tors have recently suggested that the use of an oc- possibly because of a deprogramming of the jaw ciusal stabilization splint does not have any thera- muscles^ or changes ¡n the tactile afferent impulses peutic effects at all.'^ It has been reported that the use of an occlusal stabilization splint results in changes of the con- 'Department of Prosthetic Dentistry and Stomatognatliic Physiology, Faculty of Dentistry, University of Oslo, Oslo, Norway. dyle or jaw movements while chewing.'''"'^ "Researcfi Asiociate, Department of Prosthelic Dentistry and However, the study designs and results of these Slomatognaffiic Pfiysiology, Faculty oí Dentistry, University of studies diverge. Furthermore, no conclusive evi- Oslo, Oslo, Norway. dence about the effect of splint use upon chewing 'Associate Professor, Deparfment of Prosthetic Dentistry and movements has been presented. Stomatognathic Physiology, Faculty of Dentistry, University of It was hypothesized that if the use of a stabiliza- Oslo, Oslo, Norway. •"Professor, Department of Prosthetic Dentistry and Sfomatognathic tion splint had any effect on chewing movements Physiology, Faculty of Dentistry, University of Oslo, Oslo, Norway. this would be most noticeable in individuals with different functional statuses of their masticatory sys- Reprint requests: Dr Asbjarn Jokstad, Department of Prosthetic tems. The authors therefore chose to study samples Denlfsrry and Stomatognathic Physiology, Faculty of Dentistry, University of Osio, PO BoK 1 fO9, N-0317 Oslo, Norway, e mail from populations with presumably disparate func- jolisfad®odont.uio.no tional statuses of their masticatory systems. Three

The International lournal of Prcisthnrlontic 158 Volume II, Number 2, efore and After Use of a Stabilization Splint

population groups were selected, ie, patients with have any symptoms of TMD, such as joint clicking TMD symptoms following a previous whiplash inci- or limitation of border movement range in = 14). dent,'' patients with a primary diagnosis of TMD Regarding muscle tenderness, less tban four mus- according to the research diagnostic criteria for cle points slightly tender to palpation was consid- TMD (RDC-TMD) criteria,'" and individuals with- ered as normal. out any signs and symptoms of TMD. A maxillary occiusal stabilization splint modified The aim of the study was to assess the effect of from the Michigan occiusal splint^ was made for using an occlusai stabilization splint for 6 weeks all participants. The splints were constructed to on certain parameters of chewing movements in provide separation of the posterior teeth during subjects with and without TMD symptoms. protrusion and a canine rise during lateral excur- sions. Before use the splints were adjusted to free- Materials and Methods dom in centric and to include multiple bilateral oc- ciusal contacts in the retruded contact position. All The study material comprised 42 individuals, 30 participants were instructed to wear the splint dur- women and 12 men. The age of the participants ing the night for 6 weeks. ranged from 28 to 60 years, with a mean of 42.7 Recordings of the chewing movements were per- years. The exclusion criteria were the presence of formed using an optoelectronic system (MacReflex, complete or removable partial prostheses with Qualisys) operating at 50 Hz. The equipment con- distal extensions, individuals receiving medica- sisted of three basic units: (1) two video cameras tion or other treatments for TMD during the study, with a detecting lens sensitive to infrared light, (2) a and individuals with recent facial or cervical video processor, and (3) a software program run on trauma. The participants were selected from three a Macintosh computer. An infrared flashlight placed populations and matched according to gender around the lenses and synchronized with the elec- and age, ie, each group consisted of 10 women tronic shutter illuminated the field of view. and four men. Integrated coordinate signals from the two video The first patient group (n =14) was recruited cameras enabled an analysis of the chewing move- throtjgh announcements published in local newspa- ments in three dimensions. The system was cali- pers. These participants had TMD symptoms follow- brated before each recording usinj; a reference ing a whiplash incident. All patients had complaints structure consisting of fixed spherical markers witb of frequent pain (at least four times a week) in the known positions. Reflecting markers were attached jaw muscles of at least 1 to 3 years' duration. The to tbe participant's and onto a frame located on second group consisted of TMD patients treated at the forehead. The movements of these latter markers the Faculty of Dentistry, University of Oslo in =14). were subtracted from the chin marker movements to One participant dropped out of the study and was compensate for potential head movements. therefore not included in the analysis. The participant was placed comfortably in a The examination and diagnoses of the patients dental cbair. Head movements were not restricted, were made in general according to the RDC-TMD and there was a free choice of chewing side. The criteria described by Dworkin and LeResche.'^ chewing substance was a cylindrical piece of Muscle tenderness was graded into three cate- paraffin wax, 18X8 mm, that was chewed to a gories; slight tenderness, moderate tenderness, and bolus before the recording started. Each recording severe tenderness represented by a redrawal reflex. period lasted for 20 seconds and was repeated five All masticatory muscles and muscles in the neck times. The first 10 chewing cycles during the and the shoulders were palpated, 26 sites in all. recordings were not used in the analysis. This was Joint sounds and limitation of mandibular move- done to exclude possible effects on the partici- ment were recorded for all participants. Ranges of pant's chewing caused by the unfamiliar test sub- mandibular movement (maximal unassisted open- stance.''* At the start of the recording the partici- ing, maximal assisted opening, lateral and protru- pant kept the mandible in maximal intercuspation sive excursions) were assessed using a millimeter and started chewing upon a sign given by the oper- ruler. The RCD-TMD diagnoses made in the ator. whiplash and the "ordinary" TMD group were: my- Recordings of the chewing movements were ofascial pain (n = 12 and 9), myofasciai pain and made on three occasions: H) at base line, Í2) 2 disc displacement with reduction in = 2 and 3), and weeks later before use of the splint was begun, and disc displacement with reduction (n = 0 and 1). f3J after 6 weeks of using the occiusal splint. Tbe participants in the third (control) group were In the computer software program, each masti- selected primarily among the faculty. Tbey did not catory cycle was categorized into three separate

159 The International I of Prosthodontics Chewing Before and Atier Uie ot a StahiliïaliDn Splint

Fig 1 The three chewing phases indicated by one single MaximutTi intercuspation i chewing enveiope in frontai view. The opening phase starts al 0.5 mm from the maximum intercuspation (Mi), and ends at OcclJditig phase ^ ^ 0.5 mm the most inferior point of the chevying cycie. The closing phase starts at the most interior point of the chewing cycle and ends 0.5 mm from Ml. The occluding phase was defined as an area within 0.5 mm from tvll.

Opening phase \ \ Closing phase

Table 1 Confidence Interval Limits (96%) of the Differences of Mean Measurements of Jaw Spatial Displacement, Chewing Cycle Duration, and Jaw Veiocity Cycle duration (sec) Velocity (mm/sec) spatiai dispiacement (mm) Open phase Ciosing phase Fuli cycie Open phase Closing phase Control individuals (n = 14) a -0.6 to 1.2 -0.02 to 0.01 -0.01 to 0.02 -0.05 to 0.04 -2.1 to 5.6 -4.9 to 5.0 b -0.4 to 0.6 -0.01 to 0.03 -0.01 to 0.03 0.00 to 5.7 -4.9 to 2.0 -A.i to 0.8 c -0.8 to 1.5 -0.02 to 0.03 -0.02 to 0.05 -0.04 to 0.07 -3.1 to 3.7 -8.1 to 4.6 TMD patients ((j= 13) a -3.0 to 1.6 -0.01 tcO.O3 -0.01 to 0.05 -0.05 to 0.1 -11.6 to 7.2 -12.9 to 5.4 b -0.3 to 1.4 -0.01 to 0.04 0.02 to 0.09 0.02 to 0.1 -5.3 to 4.7 -13.2 to 5.2 0 -2.4 to 2.0 -0.01 to 0.06 0.03 to 0.1 0.01 to 0.2 -12.9 to 8.0 -16.8 to 2.7 Wtiiplasti group (n= 14] a -2.2 to 1.6 -0.02 to 0.05 -0.01 to 0.04 -0.04 to 0.1 -8.4 to 4.2 -6.2 to 3.2 b -1.4 to 2.5 -0.03 to 0.05 -0.03 to 0.05 -0 05 to 0.7 -5.7 to 9.6 -3.5 to 4.6 c -1.5 to 1.8 -0.01 to 0.05 0.00 to 0.05 0.00 to 0.1 -5.8 to 5.4 -6.4 to 4.4 Differences measured befween (1) baselihe and before starting ffie use of an occiusal stabilization spiinf, (2) before starting to use tfie splint and after 6 weeks use of the spiint, and ¡3) baseiine and after 6 weeks' use of fhe spiint. Values are presented for tiie three different population sampies.

phases, ie, opening, closing, and occlusal level the baseline values of the mean spatial dispiace- phase. The occlusai level phase was defined as ment and the veiocity of the ¡aw during the three when the mandibie was located within 0.5 mm in- separate chewing cycie phases and for the mean ferior to the maximum intercuspation ¡Fig 1). The duration of the fuii chewing cycle and the three foiiowing parameters of the jaw movements were separate chewing cycle phases. The spatiai dis- measured: (V mean duration; (2) spatial displace- placement and veiocity during the opening and ment; and (3) velocity of the mandibie during the ciosing phases and duration of the separate phases chewing cycle, as weli as for the three separate of the chewing cycle for tbe three participant phases of the chewing cycle. groups is shown in Figs 2 to 4. The intraindividual changes between baseline The confidence intervai iimits (95%) of the tJif- recordings before spiint use and after splint use ferences between the baseline values, before start- were recorded. The differences of the chewing pa- ing the use of the occiusal spiint, and after 6 rameters over time were assessed by calculating weeks' use of the splint were either negligible or the 95% confidence interval limits, and tested sta- included the value of zero. Thus, no significant tlsticaiiy using Friedman's two-way analysis of changes were apparent when calculated for all variance (ANOVA). participants, for the whiplash and TMD patients together, and for the three separate participant Results groups (Table 1). The intraindividual changes in any of the re- No statistically significant differences among the corded jaw movement parameters between base- tbree participant groups (P > 0.05) were noted for line and before use of the splint as well as after 6

11, Number 2,1998 ational lournai of Prosttiodorilii Chewing Before and Afler Use of a Stabilizölion Splint

20 20 18 18 16 16 14 14 E 12

10 10 e B 6 6 4 it1 2 !3 it1 2 !3 Group Group

Fig 2 Boxplot ol fhe mean mandibular spatial displacemenl (mm) during fhe opening (ieñ) and closing ¡righf) phase of fhe chewing cycle measured al baseline. The groups are (1) individuals without TMD (n =14]; (2) TMD patienfs (n = 13); and (3) whiplash TMD paHehts (n = 14] The height of the box is the interquartile range (lOR). The whiskers indicate the largest observed value that falls within 1.5 IQR

Fig 3 Boxplot of the mean mandibular velocity (mm/sec] during the opening (Ieñ) and clos- ing (righf) phase of the chewing cycle measured af baseline The groups are (J) individuals wifhouf TMD (jj= 14); (2) TMD patients (n = 13]; and fa; whiplash TMD patients (n =14]. The height of the box is the interquartile range (IQR). The whiskers indicate the largest cbsen;ed value that falls ivithin 1.5 IQR. The sign o indicates values more fhan 1 5 IQR (outliers).

0.7 0.7 0.6 0.6 0.6 0.5 0.5 0.5 * 1 0.4 •g 0.4 ? 0.4 o o o Sä 0.3 Sä 0.3 ë 0.3 CO 0.2 0.2 tn 0.2 0.1 0.1 0.1

1 2 3 1 2 3 1 2 3 Group Group Group

Fig 4 Boxplof of the mean duration (seconds) of the opening (ieñ), closing (center), and occiusai phases (rigfil) ot the chewing cycle measured at baseline. The groups are ("ij Individuais without TMD (n = 14]; f2J TMD patients (n = 13); and fSM^iiplash TMD patients (n = 14). The height of the box is the interquartile range (lOR]. The whiskers indicate the largest observed value that falls within 1.5 lOR. The signs o and * indicate values more than 1.5 (outliers) and 3 (extremes] lOR, respectively.

nber2,1995 161 The [nternalional | ou mai of Prost iiodontii Chewing Before and After Use of a Sl.ibiiization SplinI

20 - 15 10 5 0 Baseline Before After Baseline Before Baseline Before

Fig 5 The mandibuiar spatial dispiacement (mm) during chevying at baseline, before starling to use an occiusal splint and after 6 weeks'use of an occlusal splint. Individuals without TMD (n = 14, (e/1), TMD patients (n = 13, cenie/), and whiplash TMD patienis (n=14 rígíií)

weeks of using the splint were highly variable in evaluation of the effects of splint use.^" However, the three participant groups (Fig 5). The hypothesis by testing intraindividual changes instead of inter- tests indicated no significant changes in any of the group differences, sample sizes can be reduced recorded jaw movement parameters (P> 0.05). without increasing the risk of statistical type II errors.^' Discussion The placement of the IR-reflective marker on the chin instead of on a mandibular is simpler The whiplash patients in ihe present study were and less time consuming under clinical circum- probably not representative of all whiplash patients stances. The precision is considered adequate if an because the patients were not randomly selected, area close to or below the chirt point is used where but had responded to an advertisement in the the soft tissue translation in relation to the underly- newspaper. This may indicate that their motivation ing skeletal parts is minimal.^^ Previous studies to seek help was especially high, and that they have shown that the set-up of the jaw-recording were highly concerned with their illness. system in the present study resulted in 0.7-mm ver- The matching of the two other groups to the tical and 0.6-mm sagittal differences between chin whiplash group regarding age and gender signifies and marker recordings.-^ These differences that none of the samples can be regarded as repre- are larger ihan the inlraindividual and intergroup sentative for their respective populations. Thus, ex- differences in chewing movement parameters, irt- trapolation of the recorded mean values must be dicating that the method error is higher than the evaluated cautiously. The aim of the present study changes recorded. was to elucidate the mechanism of using occlusal During chewing of , the size of the bolus splints, nol to compare sample populations. Thus, varies during consecutive chewing cycles, resulting it was considered more important to select individ- in varying jaw movements used in preparation for uals with as potentially disparate functional status swallowing.^" Therefore, a test food with a con- of their masticatory systems as possible and study stant volume seemed to be most suitable for the the intraindividual changes, rather than to compare analysis of jaw motion during chewing. In addi- the mean values in population samples. Power cal- tion, using a standardized size of a material that culations were nol used to assess ihe adequate does not degrade while chewing minimizes the sample or total study size. The reason was that risk of unpredictable jaw motion caused by there are no references in the literature as to the changes of ihe test food itself." The advantage of choice of appropriate outcome measure, in this using paraffin wax is that the consistency remains case change of jaw movement parameters, for the unchanged during chewing. A negative aspect may

lolPresthedoniii 162 Voiume n,Numher 2, 1998 ChewingBeforeand After Use Illa Stabiiiïation Splint

be that the chewing could be influenced by the parameters were not stable. Moreover, a great vari- lack of taste and softness. The test food used in the ation in changes of the chewing parameters be- present study had a relatively soft consistency. It is tween baseline and before as well as after use of uncetiain if larger differences would appear if the the splint in the patient groups was noted (see Fig test food had been of a harder consistency. How- 5). There may be differences among the sample ever, this was avoided to prevent aggravating pain populations (see Figs 2 to 4), which possibly would in the chewing muscles and/or temporomandibular be statistically significant if the sample sizes were joints of the TMD patients. increased. However, the clinical value of such a Pain in the or muscles finding would be minimal since all recordings of of mastication is often associated with a restriction jaw movements for diagnostic or monitoring pur- of mandibular movement. Therefore, it seemed poses would be inadequate because of potar diag- logical to investigate jaw movements and to ana- nostic validity.^' lyze motion to try to identify indicators of the dis- ease. Sophisticated instrumentation has been used Conclusion to record various aspects of mandibular movement and analyze jaw movement pattems. Some authors On an intraindividual basis, large variations in conclude that TMD patients have characteristic changes of chewing parameters were observed chewing patterns,^^-^'* while others refute such after using an occlusai stabilization splint for 6 findings.^" The present observations (see Figs 2 to weeks. On a group basis, the use of an occlusal 4) do not support the hypothesis that chewing stabilization splint for 6 weeks does not pre- movements are notably affected, at least regarding dictably change jaw movement parameters as jaw spatial displacement and chewing cycle time. recorded under the conditions of this study. On the other hand, it is possible that selecting TMD patients with diagnoses, initial intensity of symptoms, or etiology different than those in the References present study would have resulted in larger differ- ences in the chewing parameters. 1. Clark CT, Interocclusal appliance therapy, in: Mohl ND, Zarb GA, Carlsson GE, Rugh J (eds). A Textbook of . It is apparent that the jaw parameters measured Chicago: Quintessence, 1988;27f-284. in the present study did not change over time ¡see 2. Major FW, Nebbe B. Use and effectiveness of splint appli- Table 1). An exception is a minimal increased du- ance tberapy: Review of literature. Cranio f 997;î 5:159-f 66. ration of the closing phase and full chewing cycle 3. Ramfjord SP, Asli MM. Reflections on the Michigan ocdtisal among the TMD patients. However, the 95% con- splint. J Oral Rebabil 1994;21.49;-50O. 4. Rubinoff MS, Gross A, McCall WD. Conventional and nonoc- fidence interval is in the 0.01-to-0.2-second range, cluding splint tberapy compared for patients with myofascial which is clinically insignificant in relation to the pain dysfunction syndrome. Gen Dent 1987;35:502-506. measured values ranging between 0.3 and 0.6 sec- 5. Dabiström L. Electromyograpbic studies of craniomandibjlar dis- onds (closing phase) and between 0.6 and 1.3 sec- ordeis. A review of the literature.] Oral Rehabil 1989;16:1-2O. onds (full cycle). 6. Linde C, Isatsson G, Jonsson BG, Outcome of 6-week treat- ment with transcutaneous electric nerve stimulation com- The measured parameters varied more or less for pared with splint on symptomatic temporomandibular joint most participants. However, none of the parame- disc displacement without reduction. Acta Odontol Scand ters changed in a predictable pattern (see Fig 5). 1995;53:92-98, Thus, the data do not indicate that the use of the 7. Sbeikboleslam A, Holmgren K, Riise C. Therapeutic effects of the plane occlusal splint on signs and symptoms of cra- splint has any influence on the recorded chewing niomandibular disorders in patients with nocturnal brtJxism. J parameters. This contrasts the results of Ow et al,'" Oral Rebabil 1993;20:473^82. who reported a shortening of the duration of the 8. Weinberg LA. The role oi" muscle deconditioning for occlu- opening phase as well as the total chewing cycle sive corrective procedures.] Prosthet Dent 199I;66:250-255. and an increase in the mean opening velocity after 9. Ash MM, Ramfjord S. Occlusion, ed 4. Philadelphia: Sajnders, using an occlusal splint for 5 to 8 weeks. The re- 199.';. 10. Dahlström L, Garlsson CE, Carlsson SC. Comparison of ef- sults also contrast the results of Koyano et al,'^ fects of electromyographic biofeedback and occlusal splint who reported a shorter occlusal level phase dura- tberapy on mandibular dysfunction, Scand | Dent Res 1982; tion after the 24-hour use of an occlusal splint. The 90:151-156. different results may be explained by different peri- 11. Greene CS, Laskin DM. Splint therapy for the myofascial ods of splint use and compliance with using the pain-dysfunction (MPD) syndrome: A comparative study. J Am Dent Assoc 1972;84:624-628, splint during the test period. 12. Dao TT, Lavigne Cl, Charbonneau A, Feine JG, Lund |P. The ef- The recordings in the control group were not ficacy of oral splints in tbe treatment of myofascial pain of tbe consistent at all observations, indicating that these jawmuscles. A controlled clinical trial. Pain 1994;56:85-94.

'jmber 2, 1998 163 The Intemstionai lournal of Prosthodonlics Chewing Before and Aftpr Use of s Stabilization Splint

13. Marbach Jl, Raphael KG. Future directions in the treatment of 23. Hamborg R, Karlsson S. fviovement ahd signal analysis by chronic misculoskeletal facial pain: The role of evidence-based means of a computer-assisted system. I Oral Retiabil 1996; Cure. In; Natiohai Institutes of Health Technology Assessment 23:121-128. Conference on Management of Temporomandibular Disorders 24. Gttenhnff FA, van der Bilt A, van der Glas HW, Bosnian F. 1996. Oral Surg Orai Med Oral Pathoi 1997;B3:170-176. Control of human ¡aw elevator muscle activity durihg simu- 14. Ow RKK, Carlsson CE, |emt T. Craniomandibular disorders lated chewing with varying bolus size. Exp Brain Res 1993; and masticatory mandibular movements. | Craniomandib 96:501-512. Disord Facial Oral Pain 198B;2:96-100. 25. Lucas PW, Ow RKK, Ritchie GM, Chew CL, Keng SB. Rola- 15. Piehslinger E, Bigenzahn W, Celar A, Slavicek R. The effect of tiohship between ¡aw movement and food breakdown in occiusal splint therapy on different curve parameters of axio- human mastication. | Dent Res 1986;65:400-404. graphicTMJ tracings. Cranio]995;13;35^1. 26. Mongini F, Templa-Valenta G. A graphic and statistical analy- 16. Koyano K, Ogawa T, Sumiyoshi K, Tsukiyama Y, Ichiki R, sis of the chewing movements in function ¡nd dysfunction. J Suetsugj T. Effect of occiusal splint on masticatory movement Craniomand Pract I984;2:125-134. in healthy individuals. Cranio 1997;15:127-131. 27. Nielsen IL, Marcel T, Chuh D, Miller AJ. Patterns of mandibu- 17. Epsteih ]B. Temporomandibular disorders, facial pain and lar movements ih sub¡ects with craniomandibular disorders. | headache following motor vehicle accidents. | Can Dent Prosthet Dent 1990;63;202-217. Assoc 1992;58:488^90. 28. Kuwahara T, MIyauchi S, Maruyama T. Clinical classiticatior: 18. Dworkin SF, LeResche I.. Research diagnostic criteria for tem- of the patterns of mandibular movements during mastication poromandibular disorders: Review, criteria, examinations and in subjects with TMJ disorders. Int ¡ Prosthodont ]992;5: specifications, critique. J Craniomandib Disord Facial Oral 122-129. Pain 1992;2:301-355. 29. Sato S, Goto S, Takanezawa H, Kawamura H, Motegi K. 19. Jemt T, Hedegârd B. Reproducibility of chewing rhythm and Electromyographic and kinesiographic study In patients wifh oí mandibular displacements during chewing. J Oral Rehabil nonreducing disk displacement of the temporomandibular l982;9:531-537. ioint. Oral Surg Oral Med Oral Pathoi ]996;8]:516-521. 30. Dao TT, Lavigne G|, FemeJC, Tanguay R, Lund IP. Power and 30. Mohl ND, McCall WD, Lund JP, Plesh O. Devices for the di- sample size calculations for clinical trials of myofasciai pain agnosis and treatment of temporomandibular disorders. Part I: of jaw muscles. J Dent Res 199l,-70:118-122. Introduction, scientific evidence and jaw tracking. J Prosthel 21. Cohen ¡. Statistical Power Analysis foi the Behavioral Sciences, Dehtl99n;63:198-201- ed2. Hillsdale: Lawrence Erlbaum, l988;1-74. 31. Lund JP, Widmer CG, Feine JS. Validity of diagnostic and 22. Ekfeldt A, |emt T, Mânsson L. Interocclusal distance measure- monitoring tests used for temporomandibular disorders, J ment comparing chin and tooth reference points. J Prosthet Dent Res 1995;74:1133-1143. Dent 1982;47:560-563.

iiterature Abstract

The rehabilitation of the severely resorbed maxilla by simultaneous place- ment of autogenous grafts and implants: A 10-year evaluation

In 20 consecutive patients witti advanced maxillary résorption, 13 were treated witti onlay grafts and seven with sinus inlay grafts. Another seven consecutive patients with maxillary discontinuity (either tram a congenital defect or a tumor) were also treated with bone grafls. In all cases corticocancelious hip grafts were used and implants were placed simultane- ously, thereby also tixafing the grafts. Two surgical teams were involved, one at the oral site and the other at the hip site, to reduce the extracorporal time. Tine observation period mas 1 to 1G years. The cumulative success rate for the implants was 95% tor both the onlay and the sinus inlay groups but less than 50% tor the the group witli maxillary discontinuities. The success rate tor the two first groups was higher fhan previously reported, which was ex- plained by the short extracorporal time for the gratts. Also discussed is the possibility that hyperDaric oxygen might improve the poor results tor the disoontinuity group.

«an Steenberghe D, Naert I, Bossuyt M. De Mars G, Calberson L. Ghyselen J, Brânemark P.I. CItn Orai/ni-esM 997-1-102-108 Reterences: 25. Re prim requests: DrD. van Steenberghe, Catholic University Leuven, Department ot Periodontoiogy, Capucijnenvoer 7, B-3Q00 Leaver, Belgium-SP

a I of Proslhodontii 164 Volumen,t^um tier 2,1998