Restorative

Cervical hypersensitivity. Part ili: Resolution following occiusai equilibration

Thomas A. Coleman, DDSVJohn O. Grippo, DDS^/Keith E. Kinderknecht,

Objective: This retrospective study was designed to investigate changes of cervical dsntin hypersensitiv- ity (CDH) in response fo occlusal equilibration. Method and materials: Wntten records lor 250 active-care patients were randomly selected and analyzed lor associations between CDH, and its resolution following occlusal equilibration. Patients in group A (treatment) and B (delayed treatment] received occlusal equili- bration following the détection of verified CDH using the air indexing melhod. Group C patients were not detected with verified CDH during the study period of 17 years. The resolution of CDH was measured by the loss of a positive patient threshold response to air stimulation. Results; Significant associations ex- isted between CDH, hyp erf unction, parafunction, and abfractive lesions. Furthermore, it was found that oc- clusai equilibration resulted in the long-term resolution of CDH. Conclusions: The resolution of CDH by occlusal equilibration, thus negating the null hypothesis, suggests that further studies are indicated to eval- uate the impact of these findings upon restoring and maintaining health of the masticatory system (Quintessence int 2003,34:427-434)

Key words; abfractive lesions, air indexing method, cervical dentin hypersensitivity (CDH),occlusal equilibration

have been theorized to develop over time in response CLiNiCAL RELEVANCE: Occlusal examination, analy- to hyperfunctional or parafunctional forces, which re- sis, and judicious equilibration is indicated whenever sult in microfractures in cervical dentin.= These stress- CDH is present. The reduction of CDH, measured by the induced hard tissue iesions appear to be exacerbated air indexing method, suggests an appropriate clinical ap- by erosion-corrosion and tootbbrush/dentifrice abra- plication of occlusal equilibration in the long-term man- sion.^' Horizontal loading forces have been implicated agement of CDH. in the formation of abfractive lésions.^"'-' Cervical dentin hypersensitivity seems to be coincident dunng the formative stage or active period of .-* n air indexing method^ was recently introdtjced to The masticatory system comprises three basic com- Adetect and quantify the degree of cervicai dentin ponents: temporomandibular (TM) joints, muscles of hypersensitivity (CDH),'-" Associations have been mastication, and teeth. A nondeflected centric relation noted between CDH and abfractive lesions in that (CR) where centric occlusion (CO) equals maximal in- they were predominantly located on the cervicai facia! tercuspation (MI) with a fuliy seated position of the surfaces of and molars." Abfractive iesions temporomandibular condyle/disc assembly in the fossa as defined by Dawson'" and others,'^-^' was utilized during occiusai anaiysis in the present study. Dawson introduced a classification system for dentai occlusions 'Private Practice, Shaftsbury, Vermont. that relates maximal intercuspation in CR to TM joint ^Senior Lecturer, Department ot Biomédical Engineering, Western New health and masticatory muscle response to tooth de- England, Springtield, Massachusetts. flections.^' Williamson and Lundquist" found that ca- =Directcr of Giaduate Prostliodontics, School of Dentistry. West Virginia nine-guided laterotrusion or anterior guidance in pro- University, Morgaritown, West Virginia. trusion decreased masseter and temporal muscle Reprint requesls: Dr Thomas A. Coleman, Shaftsbury Medical Bijilding, contractilib;, whereas posterior occlusal contact during Box 230. Shaftsbury, VT 05362. Fax; 802-442-2072.

Quintessence International 427 • Coleman et al

these two excursions produced more intense muscular ity and deflection by the tongue, cheek, or . Local contraction. These concepts have been verified by anesthesia, muscle fatigue, and the dentist-patient rela- Kerstein and Wright^-* and Kerstein^^ with the use of a tionship may also hinder occlusal evaluation and ther- T-Scan to demonstrate that reduced posterior contact apy. Although not used during this retrospective study, in eccentric tnovements or laterotrusion reduces mas- computerized force analysis may improve the detection seter and temporalis EMG activity. The T-Scan 11 is a and quantification of tooth contacts,^'' Microsoft Windows R (Microsoft) complaint comput- Successful occlusal analysis and restorative treat- erized occlusal analysis system tbat gathers occlusal ment requires recognizing the dynamics of the masti- contact force and time sequencing data through an catory system to both vertical and horizontal stresses intraoral electronically powered pressure-measuring upon teeth.'' Mounted study casts may aid the clini- sensor,-^ The dynamic interrelationships of teeth, cian in the analysis of static occlusal contacts, but they periodontium, muscles of mastication, and temporo- lack information regarding the horizontal loading mandlbular ¡oints under function are the basis for oc- forces upon teeth. Dental/neuromuscular, gravita- clusal therapy designed to alleviate pathology related tional/postural, skeletal/structural, or systemic oc- to the masticatory system.'*-" clusal modifiers may alter occlusal stress upon teeth in Historically, occlusal therapy has been provided by function and parafunction," Spranger's in vitro analy- clinicians based upon the signs of chronic periodontal sis of study casts found that woriiing and nonworking hyperfunction, such as tooth hypermobility and/or excursive forces produce 10 to 20 times greater flexure vertical bone loss,-'"'' The introduction of occlusal to teeth than do vertical loading forces.'^ Clinical data prematurities as little as 80 ^m may result in a 7O'^/o in- suggests that flexural stress seems to be a contributing crease in occlusal forces upon teeth,^" Occlusal deflec- etiotogic factor in the genesis of both CDH and the tions of 500 pm stimulate periodontal receptors formation of abfractive lesions,'' which, in turn, can induce refjex contraction by the The purpose of this retrospective clinical study was muscles of mastication.^- Occlusal devices may reduce to evaluate changes of CDH in response to occlusal occlusal stress to teeth and therefore the tone of con- equilibration in that CDH may be a precursor and tractile muscles of mastication."'-"'' Options for the pathognomonic sign of active abfraction. The null hy- treatment of periodontal deflections are occlusal equi- pothesis is that occlusal equilibration has no effect on libration or occlusal device fabrication. CDH. A neurologic influence upon the contraction and relaxation cycles of the muscles of mastication may also result from pulpal stimulation,^'' Cervical dentin METHOD AND MATERIALS hypersensitivity has been identified as a neurogenic pulpal response to stimulation from Database open dentin tubules to cold, air, electrical stimulation, acid exposure, tactile stimulation, or combinations of A population of 250 active-care patients older than 20 these stimuli.'^"''" Neurogenic may also years of age at the end of the 1979-1996 retrospective mediate or intensify the pulpal response of CDH to study period were randomly selected from a general these stimuli.-''' The association of CDH to the pres- dental practice. These patients were examined for the ence of abfractive lesions by location and distribution presence or abscnee of CDH using the "air indexing indicates that CDH may result from excessive func- method,"''' Groups A and B included only those pa- tional or parafunctional occlusai stress."' tients detected with a "verifled positive threshold pa- Occlusal prematurities and deflective occlusal con- tient response" to an air stimulus (ie, sensitive to air), tacts resulting in CDH, abfractive lesions, or perio- whereas group C were those patients without a veri- dontal mobility can be so minor that they are neither fled positive air index (ie, insensitive to air)." perceived by patients nor detected by dentists. The abil- Oeclusal therapy was provided for patients in groups ity of a dentate individual to perceive an occlusal pre- A and B to teeth detected with a verified positive re- maturity occurs at between 20 to 90 ]im.'"' Tactile sensi- sponse to air stimulation (CDH), Patients were as- tivity during chewing has been identified as detecting signed to group A (treatment) when occlusal therapy differences as small as 0.035 inches,''' In mathematic was provided at less than 30 days from the detection of conversion, 20 \im equals O.OOOS inches, and 80 pm verifled CDH. Group B (delayed treatment) were those equals 0,0031 inches. Articulating papers in standard patients treated by occlusal equilibration at an interval use for clinical dentistry arc between 0,0015 and 0.0035 of 30 days or more from the diagnosis of verified CDH. inches thick. The use of articulating papers to obtain in- None of fhe paflents in group C were diagnosed with fonnation during occlusal analysis/equilibration is chal- verifled CDH; however, some did receive occlusal ther- lenging to the clinician due to moisture of the oral cav- apy based upon clinical and/or radiographie signs and

428 Voiume 34. Number 6, 2003 — Coleman et ai symptoms of secondary . These signs or cement, acidie dietary influences, or when exces- and symptoms included vertical bone loss and/or in- sively abrasive habits existed. Further- creased mobility of individual teeth associated with more, patients with a recent (7 to 14 days) history of functional and parafunctional forces. periodontal surgery or exodontia also were excluded The data analysis excluded patients of less than 1 from both groups A and B, year, those lacking completion of regular dental care, and those whose last treatment date was prior to Occiusal equiiibration 1994. Retrospective analysis included examination of written records from 1979 to 1996 for all 250 patients Occlusal equilibrations to enamel and/or restorations who were then assigned to groups A, B, or C on the estimated at 100 pm or less were performed, guided by basis of the air indexing method.^ Collection of addi- articulating paper and occlusal indicator wax. These tional data included patient age. Angle's classiflcation equilibrations were provided to teeth diagnosed with of occlusion, number of treatment years, number of CDH using the air indexing method.' All patients di- teeth, air indexing data, type of occlusal interi'erence, agnosed with verifled CDH received equilibration and abfractive lesions, and signs/symptoms of aetive para- were assigned to groups A or B, except those excluded function. The data were processed on a personal com- as described. Excluded patients and those without a puter using a spreadsbeet program (Excel 5,0, diagnosis of a verified positive threshold response to Microsoft). air stimulation were assigned to group C, Some mem- bers of group C received occlusal equilibration based Occiusai analysis upon traditional signs or symptoms of secondary oc- clusal trauma/occlusomuscular disharmony. Patients Routine occlusal analysis was provided for all patients who never received occlusal equilibrations during the in this retrospective study based upon patient com- 17-year study period were also assigned to group C. plaints, detection oí cervical dentin hypersensitivity, Equilibrations were performed with abrasive discs or and/or periodontal signs of traumatic occlusion. high-speed burs with a gentle brushstroke, to reduce Findings of radiographie evidence of vertical bone the articulation recordings. loss, tooth mobility, CDH, mastication sensitivity, , or patient complaint of occlusomuscular pain were the indicators for occlusal equilibration. Patients RESULTS were examined using a variety of standard articulating papers, occlusal indicator waxes, analysis of mounted Table 1 comparisons of age, number of teeth, and study casts, excursion limits, comparisons of current/ years in treatment disclosed similarities in the study previous intraoral radiographs, and CR techniques. samples for groups A, B, and C, The sums of groups A The long-term nature of this retrospective study and B correspond to group I of the previous retro- (1979-1996) and the goal ol successful patient treat- spective study by Coleman et al,-» Group B (delayed ment occasioned technical changes, such as improve- treatment) included 19 patients, wbereas group A ment of articulating papers, the introduction of the (treatment) disclosed 82 patients witb verified posi- fluid control block,' and the use of bimanual manipu- tive tbreshold patient responses to air stimulation. lation for CR were implemented for more precise oc- Group C (149 patients} corresponds to group II from clusal analysis as state-of-the-art advances occurred, the previous study by Coleman et al.** Tbis previously Occlusal analysis included radiographie evaluation; published retrospective study associating patients direction of tooth deflection for mobile teeth that in- witb verifled CDH to abfraetive lesions found tbat terrupt the arc of mandibular closure in CR; a verifica- 76% of patients in groups A and B were detected witb tion (7 to 10 days) following a diagnosis of a positive abfractive lesions. Only 39^/0 of the patients within air index; an attempt to retain centric holding cusp group C were detected with this type of hard tissue le- contacts; and location of occlusal interferences during sion.'' Aetive parafunction was diagnosed in SO^/o of mandibular movements. During occlusal adjustments, group A, 47,4% of group B, and only 15,4o/o of group an attempt was made to gain or retain cuspid-rise lat- C patients. erotrusion wben possible. The number of teeth diagnosed with CDH for both Parients were excluded from occlusal equilibration groups A and B is illustrated in Fig 1. It was found groups A and B when the etiology of CDH seemed re- among the 101 patients in these two groups that 43,6% lated to causes other than deflective occlusal contacts. had CDH involving one tooth, 22.8% with two teeth, These exclusions included a restoration that lacked a and only one patient with 13 teeth sensitive to air stimu- protective base, a tooth that had a recent vital ex- lation. A total of 246 teeth were diagnosed with verified posure, a diagnosis of irritation from a protective base CDH in these two groups over fhe 17-year study period.

429 Quintessence international • Coleman et al

TABLE 1 Summary of comparisons of groups A, B and C (1979 to 1996)

Groups

A B C

Female Maie Both Female Male Botn Female Male Both

No. ot patients 42 40 82 13 6 19 11 72 149 Age at beginning of dental care Mean 37 4t 39 32 45 36 39 42 40 Median 48 46 47 33 46 41 35 41 38 Standard deviation 11 12 12 10 13 30 19 15 17 Mean no ot teeth 26 27 26 26 26 26 25 24 24 Mean years in treatment 9 10 10 13 17 14 9 9 9 No, ot patients with 23 18 41 7 2 9 12 11 23 active parafunction (%] (50.0%] (47.4%) (15,4%) A = patients wilh verified CDH equilibrated iv thir 30 days: B - patients mitti verified CDH equilibrated 30 äays or greater; C = patients with no verilied CDH.

Fig 1 Distribution ot patients with cervical dentin hypersensitivity (CDH] when groups A and B are combined (n = 101].

1234567 89 13 No. of teeth with verified COH per patient

TabJe 2 discloses correlations between the detection tion visits to resolve CDH, Correlation analysis found and resolution of CDH following the equilibration of that 31% of group A and 48% of group B incidents of teeth in groups A and B, All teeth diagnosed with a CDH diagnosis had an etiology related to hyperfunc- verified CDH, except those excluded, received oc- tional contacts from recent dental treatment. The non- clusa! equilibration irrespective to the presence or ab- measured results of periodontal deflections after equi- sence of prior restorative care. Retrospective analysis librations for group C patients were not included with found documented resolution of CDH for all 246 the CDH data presented in Table 2, teeth within this study. The results revealed that an av- Tables 3a and 3b present the statistical analysis of oc- erage of two equilibration visits were required to re- clusal equilibration in groups A and B, The time interval solve CDH for both groups A and B. Recurrent CDH hetween diagnosis, using the air indexing method and in the same treatment quadrant over the 17-year study initial occlusal equilihration, was an average of 7 days in period was 15% for group A and only 5% for group B, group A and 92 days (delayed for various reasons) in This CDH was resolved by occlusal equilibration on group B, Second, third, or fourth equilibration visits oc- an average of two visits for group A and three visits curred if CDH was not resolved at subsequent appoint- for the one patient in group B, Only 12"/o of patients ments. Ali patients in group C were without verified within either group required four or more equilibra- CDH and were not included in Tables 3a and 3b,

430 Volume 34. Number 6. 2003 • Coleman et al

TABLE 2 Equilibration data and equilibrated CDH associated to recent dental treatment for groups A and B

Groups A(n = 2) B (h = 19)

Female Male Both Female Maie E 0th

Total equilibration visits for positive air indexed teelh' 220 30 Mean visits to resolve CDH 2 2 Total patients relieved of CDH by occlusal equilibration 82 19 Patients with recurrent CDH following equilibration (%) 12(15) 1(5) Total equilibration visits for secondary positive 19 3 air indexed teeth" Average no. of visits to resolve seoondary 2 3 oocurence of CDH Percentage of patients requiring 4 or more visits of 12 10 occlusal equilibration to resolve CDH No. of incidents of CDHt 66 55 121 15 6 21 No. of incidents of CDH related to dental treatment (%)' 19 (29) 18(33) 37(31) 9 (60) 1 (17) 10(48) Operative 8 9 17 4 0 4 Crown 5 4 9 5 1 6 Fjjced bridge 6 3 9 0 0 0 Extractions (more than 7 days postop) 0 1 1 0 0 0 Partial denture 0 1 1 0 0 0 A = palierts with veiified CDH equilibrated within 30 days; B = patients with verified CDiH equilibrated 30 days or g eater. "One treatment visit may relate to equilibration of severai teeth diagnosed with verified CDH. 'Note that some patients had miJitiple CDiH teeth.

TABLE 3a Distribution of acclusal equilibrations for groups A and B

Groups A E Mean no. Total Mean no. Total Treatment time of days incidents of days ihcidehts Between diagnosis and first treatment 7 121 92 21 Between first and second treatment 17 57 19 7 Between second and third treatment 15 26 14 3 Between third and tourtti treatmeht 8 15 12 2 A = patients with verified CDH equilibrated within 30 days; B = palients mtii verified CDH eq üibrated 30 days or grealer.

TABLE 3b Location of occlusal equilibrations for groups A and B

Treatment stage Group A Group B Adjustment First Second Third Foürth+ First Second Third Fourth+ Working 65 31 10 3 8 2 0 0 Nonworking 10 1 0 0 3 2 1 1 Centric 5 1 1 1 1 0 0 0 Protrusive 4 1 0 0 3 0 0 0 Working and nonworking 28 19 11 8 6 3 2 1 Centric and protrusive 2 0 0 0 0 0 0 0 Working and centric 5 2 2 1 0 0 0 0 Working/n onworking/centric 2 2 2 2 0 0 0 • Totai 121 57 26 15 21 7 3 2 A = patients with verified CDH equilibrated within 30 days; B = 3 at ie nts withverified CDH equilibrated 30 days or greater.

Quintessence International 431 • Coleman et al

port the contention that excessive misdirected func- D Patients with CDH (groups A and B) tional or parafunctionai forces upon teeth appear to • Patents without CDH (group C¡ be related to the presence of CDH. The formation of 90 77 groups A and B provides study groups, wberein the 80 only variable is the time between diagnosis and oc- 57 58 clusal adjustment.'' § 60 • 1 , Cervical dentin hypersensitivity most frequently in- S. 50 •h 43 42 volved only one tooth (see Fig 1). As the number of Ö 40 —36- 1 -- sensitive teeth per patient increased, the number of ^ 30 23 patients with CDH decreased. Although not illustrated 30 - by Fig 1, a similar distribution between CDH and - • • • 10 —r - abfractive lesions was found.-' Sharav et al'^ found that 0 = 55 99 6 8 35 25 5 17 pulp stimulation may alter contractility of masseter Class 1 Class II. Class II. Class 111 and temporalis muscles. Chronic pulp stimulation division 1 division 3 such as that occurring with CDH creates the potential Angle's classification for masticatory muscle accommodation. Since the masking of CDH by desensitizing dentifrices alters clinical air indexing data, it is likely that increased risk Fig 2 Association ot Angle's classification to patients with anc of tooth fracture, pathologic muscular accommoda- without veriliect cervical dentin hypersehsitivity (CDH). tion, or tooth mobility may result when occlusal disharmony remains uncorrected. Palliative treatment of CDH without occlusal equilibration may contribute to future dental problems. Tables 3a and 3b also identify various types of de- Data summarized in Table 2 revealed that CDH re- flective or premature contacts that were adjusted on solved on average after two visits following occlusai teeth with a verified and quantified CDH. The greatest equilibration for both the active and delayed-treat- number of adjustmetits to both groups A and B oc- ment groups. Dclayed-treatment group B included curred on working cusp inclines, which corresponds only one patient with recurrent CDH in the same to the overwhelming buccal locations of CDH.'' equilibration quadrant. The resolution of CDH in only Locations of premature occlusal contacts were similar one patient who required three equilibration visits is for both groups A and B. not significant for data interpretation but follows the Figure 2 correlates the percent frequency of CDH same clinical pattern of the loss of dentin sensitivity detected for each Angle's classification group. Among following occlusal treatment. Most significant was the the total 250 pafients, approximately 40% (grotips A finding that all of group A and B patients were re- and B) were diagnosed with CDH and 60% {group C) lieved of CDH, which strongly supports the previously without CDH. Fifty-eight percent of Class II, division stated contention that chronic occlusal disharmony 2 patients were detected with CDH and 770/0 of Class can be a significant etiologic factor of CDH. Recent HI patients without CDH. The detection of CDH dental treatment was associated with the initiation of among Class I and Class 11, division 1 patients was CDH for one third to one half of the incidents for pa- 56% and 43%, respectively. tients in groups A and B. The resolution of verified CDH by occlusal adjustment was found to be long lasting, with only lS^^/o and 5% recurrence rates for DISCUSSION groups A and B, respectively, over an average pafient treatment period of approximately 10 years. The data The interrelationships between TM joint function, strongly supports the rejection of the null hypothesis contracfion and release cycles of the muscles of masti- that occlusal equilibration has no effect on CDH. cation, and occlusal contacts between teeth must be Tables 3a and 3b disclose occlusal equilibration sta- understood prior to providing any occlusal therapy. tistics for groups A and B. Cervical dentin bypersensi- For example, a MI position may yield different record- tivity was resolved by occlusal equilibration, whether ings of tooth contacts when compared to those this treatment was rendered after an average of 7 days recorded in the CO position with the condyles in CR. (group A), or an average of 92 days (group B) follow- Groups A, B, and C (see Table 1) were evaluated in ing detection of a verified positive response to air this correlative retrospective study based upon the stimulafion. If occlusal disharmony results in forces on presence or absence of a verified CDH diagnosed by teeth that produce cervical microfractures with open the air indexing method. The results of this study sup- dentin tubuics faster than saliva can remineralize or

432 Volume 34, Number 6. 2003 • Coleman et al

occlude them, mechanoreceptor hypersensitivity from the resolution of CDH following occlusal equilibra- this exposed denfln may occur. tion. The use of desensitizing dentifrices, cervical The events of microfracture or physiochemical loss restorations, dentin bonding agents, or medicaments of crystals in cervical regions may also to resolve CDH may inadvertently mask this symptom lead to a pulpal neurogenic inflammatory response In of occlusal disharmony. actively abfracting teeth. Pashley^^ has stated that the release of neuropeptides such as substance P (SP), cal- citonin gene-related peptide (CGRP), and neurokinins CONCLUSION (NKAand NKB) tnay promulgate and intensify dentin hypersensitivity Whether by mechanoreceptor stimu- The data from this long-term, correlative, retrospective lation or neurogenic intlammation, the etiology of study (1979-1996) confirms that verified and quantified chronic CDH appears to be related in part to occlusal cervical dentin hypersensitivity is directly related to oc- disharmony. The data frotu Fig 1. Tables 2, 3a, and 3b clusal disharmony, fudicious occlusal analysis and equi- suggest that the detection and quantiflcation of CDH libration are indicated and can predictably eliininate by the air indexing method is a reliable tool for identi- CDH, Furthermore, these results negate the null hy- fying teeth with potential occlusal disharmony and pothesis that occlusal equilibration has no effect on evaluating the efficacy of occlusai equilibration. CDH. Additional clinical studies are suggested to cor- Coleman et al'' revealed a predominant buccal loca- roborate these findings and to evaluate the relationship tion of both CDH and abfractive lesions in premolars of CDH upon the health of the total masticatory system. and molars. Tables 3a and 3b illustrate that equilibration to mostly worldng contacts/inclines led to CDH resolu- tion. Laterotrusive occlusal contacts are located on the ACKNOWLEDGMENTS buccal cusp inclines except for Angle's Class II! patients. Figure 2 compared distributions of patients for each The ajthors wish lo ackno'A'ledge Gordoii Chrislensen, DDS, MSD, Angle's classification with the presence or lack of PhD; Sebastian Ciancio, DDS, PtiD; Peter Dawson, DDS; Davis CDH, Forty percent of patients (groups A and B) in Carlnpo, DDS, Robert Kerstein, DMD; Jumes R MtKee, DDS; Kenneth Malament. DDS, MScD; Norman Mohl, DDS, PhD; Jeffrey the study of 250 patients were detected with CDH, Okeson, DMD; and David H. Paihley, DMD, PhD, for iheir assis- Nearly 40% of Class I and Class II, division 1 patients tance, guidance, and encouragement. were detected with CDH, Angle's Class II, division 2 patients were detected with the highest percentage (58Ö/0) of CDH, whereas Class HI patients had the REFERENCES least (23%), These results suggest that restricted arch forms characteristic with Class II, division 2 patients, 1 Coleman TA, Kinderkrecht KE, Cen'ical dentin hypersensi- who lack anterior guidance, increase the incidence of tivity: Part I: The air indexing method. Quintessence Ini CDH from occlusal stress, A low risk of CDH is asso- 2000:31:461-465. 2. Kanapka JA. Over-the-counter dentifrices in the treatment ciated with Class HI patients where horizontal oc- of tooth hypersensitivity. Dent Clin North Am 1990,54: clusal stresses are at a minimum, 545-560. Dawson'^ and others'^--' have described a CR posi- 3. Martin EJ. Tending to tenderness: GPs get hip to new hy- tion of the condyle and disc within the fossa and an persensitivity products, AGD Impact 1^97:25(11¡:19-20. occlusai classification system for categorizing TM 4. Coleman TA, Grippo JO, Kinderkneeht KE, Cervical dentin health or lack thereof. Ruse and Sheikholeslam" and hypersensitivity: Part II: Associations with abfractive le- Holmgren et al"^-" found that occlusal prematurities sions. Quintessence Int 2000:51:466-473, stimulated periodontal receptors which altered the 5. Grippo JO, Abtractions: A new classification of hard tissue lesions ol teeth. I Esthet Dent 1991;5:I4-19. contractility of masseter and temporalis muscles. 6. Grippo JO, Simring M. Dental "erosion" revisited. J Am Several papers have related chronic pulp stimulation Dent Assoc 1995; 126:619-630, to occlusal stress witiiin the masticatory system.'-'' 7 Tyas MJ. The class V lesion aetiology and restoration. 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