The Degree to Which Dental Attrition in Modern Society Is a Function of Age and of Canine Contact

The Degree to Which Dental Attrition in Modern Society is a Function of Age and of Canine Contact

Donald A. Seligman, DDS Dental attrition ranked according to a validated severity scale was Adjunct Assistant Professor correlated with age as a proxy for functional wear in 148 asymp- Section of Orofscial Pain and Occlusion tomatic subjects. Anterior, posterior, mediotrusive, laterotrusive, Andrew G. Pullinger, DDS, MSc and total attrition severity teas analyzed. The geometric contribu- Professor tion of canine attrition to tbe variance of posterior attrition was Section of Orofacial Pain and Occlusion also tested through correlations, and the time span required to University of California. Los Angeles record a statistically significant difference in attrition using tbe School of Dentistry scale was determined. Age explained 12.6% of the differences in Los Angeles. California the total attrition scores (P < .001, Spearman's rho), 6.4% of the anterior scores (P < .01), and 20.9% of the laterotrusive scores Correspondence to: Dr Donald A. Seligman iP < .0001). Canine wear in subjects aged 20 to 49 years explained Section of Orofacial Pain and Occlusion between 20% to 34% of tbe posterior attrition (T < .05 to CHS 43-009 1' < .001), 6% to 36% of tbe mediotrusive attrition (? < .05 to University of California, Los Angeles f < .01), and 20% to 29% of tbe laterotrusive attrition (P < .05 to School of Dentistry ? < .001). At least 20 to 30 years was necessary to show significant Los Angeles. California 90024 clinical differences, except tbat laterotrusive attrition changes could be discriminated in only 10 years for tbe 20- to 29-year-old group. Notable attrition was already evident in tbe 20- to 29-year-olds, and accelerated wear rates prior to age 20 years were not maintained in most areas of tbe dentition. A nonlinear progression with age was observed, thereby inhibiting prediction of subsequent attrition from prior levels. Attrition was concluded to bave multifactorial etiology, witb age and tbe geometry of canine guidance having a significant influence, in addition to commonly accepted parafunction. J ÜRÜFACIAL PAIN l995;9:266-275.

key words: dentai attrition, age, canine guidance

ltbough dental attrition is a cumuiative record of both functionai and parafunctionai wear, it is often used by the clini- Acian as evidence of current bruxism. An estimate of the ievei of ongoing bruxism is particuiariy important in designing dentai restorations, or in deciphering whether bruxism may be a compii- cating component of a patient's symptomatology. Thus, it wouid be usefui to know bow much attrition is attributabie to bruxism and how much is attributabie to other factors. The current articie describes estimates of the infiuence of age on attrition as a proxy for functionai wear in a cross-sectionai, case history study of asymptomatic subjects across a broad age range (20 to 72 years). This inciudes subquestions regarding the necessary age range to discern a ciinicai difference in dental attrition and whether the record of past wear can predict future group wear rates. Additionaliy, the authors examined whether the amount of posterior tootb attrition is mereiy a refiection of the geometric pattern of wear once canine and incisor guidance has been reduced.

266 Volume 9. Number 3. 1995 Seligman/Pullinger

Dentists commonly ignore the functional contri- ity and location of wear facets, as described previ- butions and indict all noticeable attrition in modern ously,'' All scoring was performed by one cali- society as abnormal. In comparison, advanced den- brated observer after hoth authors evaluated 10 tal attrition was concluded to be normal in native casts selected at random. skull samples, in which most occlusal anatomy was The severity scoring was a contraction of the abraded away by 12 years of age due to diet and method by Richards and Brown" abbreviated to use of the dentition as a tool,' Civen the lack of fewer groups, owing to the inability in this study abrasive diet in modern society, functional wear is to absolutely identify dentin exposure on dental expected to occur more slowly than was found in casts. All scoring was performed according to the skull study records of primitive societies.' tn devel- following five-point scale (Fig 1): oped countries, mutual protection occlusion pre- serves occlusal anatomy into adulthood. Never- 0 = No wear theless, canine guidance is usually replaced by group 1 = Minimal wear function during young adulthood and becomes the 2 - Noticeable flattening parallel to the occluding normal occlusal pattern by middle age.' planes 3 = Flattening of cusps or grooves Because functional wear in modern samples 4 = Total loss of contour and/or dentin exposure occurs slowly,•'•' age was proposed as a reasonable when identifiable proxy for studying this kind of attrition. However, little difference was found in attrition scores ac- The facets were graded in seven zones: incisor; cording to age of nonpatients within an age range right and left canine; right and left premolar and of 19 to 40 years in an earlier study." It was molar laterotrusion (interpreted as "a" and "c" hypothesized that a large proportion of the preced- contact locations. Fig 1); and right and left premo- ing attrition observed in this population occurred lar and molar mediotrusion (interpreted as "b" early as a result of parafunction in teenage and contact locations. Fig 1). The worst score finding childhood years and plateaued across the 19- to was recorded in each zone. 40-year-age range represented. To discern and fol- The maximum possible laterotrusion score for the low the effects of subsequent functional wear, the posterior dentition was 2 premolar and 2 molar current study examined an expanded age range. zones X 2 facet locations X maximum severit}' score The specific null hypotheses tested were the of 4 = 32. The maximum possible mediotrusion follovi'ing; score for the posterior dentition was 2 premolar and 2 molar zones X 1 facet location X maximum sever- 1. Attrition is not directly correlated with age. ity score of 4 = 16. The maximum possible anterior 2. There is no minimum age range for discerning score was 1 incisor and 2 canine zones X 1 facet a longitudinal difference in attrition by use of location X maximum severity score of 4 = 12. A a severity ranking. total artririon score of 60 was the sum of the individ- 3. Canine attrition is not directly correlated with ual anterior and posterior attrition scores. posterior attrition.

Statistical Analysis Materjals and Methods To increase rhe power through the use of sufficient numbers of subjects and to reduce beta-type errors (defined as a statistical determination of no differ- Subjects ence when one actually exists), 10 years was the A total of 148 asymptomatic subjects (48 women, minimum age interval used in the analysis. A dif- 100 men; aged 20 to 72 years) were screened to ference of i" < .05 was defined as significant. A Spearman's rank correlation was performed exclude any subjects with symptoms, signs, or his- for the total attrition score against age to estimate tory of temporomandibular disorders from a pop- the amount of the variance in the attrition scores ulation of dental and dental hygiene students and that could be explained by age. general denral patients from a private practice set- The score rankings for the different age groups ting (DAS), were compared through a Mann-Whitney U test to determine the minimal age range needed to show a Data Collection cross-sectional difference in attrition scores. All samples were examined according to the same A Spearman's rank correlation was performed strict criteria.' Dental casts were graded for sever- for the mediotrusive and laterotrusive wear scores

Journal of Orofacial Psm 267 Seligman/Pjllinger

Fig 1 Attrition score criteria (left and center): 1 point - minimal wear of cusp or incisai tips; 2 points = facets parallel to rhe normal planes of contour; 3 points - noticeable flattening of cusps or incisai edges; 4 points T^ total loss of contour and dentin exposure when identifiable. The "a" and "c" locations (right) correspond to contact in laterotrusion, and rhe "b" location corresponds to mediotrusion posterior tooth facets, (B - buccal, L = lingual,)

against the canine wear scores for each age range age 40 to 49 years and the mediotrusion score to estimate the amount of the variance in the pos- until age 50 to 59 years (Tables 1 to 3, Fig 3). The terior attrition scores that could be explained by laterotrusive median scores showed a large canine attrition. increase occurring between the 20- to 29- and the 30- to 39-year-old age groups, and tben plateaued until age 50 to 59 years (Table 4, Fig 2). Results An age separation of at least 20 to 30 years was necessary to show clinical differences in attrition The correlation between age and the total attrition scores for most attrition groups (Tables 5 to 8), score in asytnptomatic subjects was statistically sig- Laterotrusive attrition was the exception (Table 8) nificant but low (p = .355, t = 4,594, df ^ 146, F < in that a statistically significant difference was dis- .001), and as a proxy for functional wear, the cor- cernable in just a 10-year period for the 20- ro 29- relation explained only 12.6% (p-) of the total attri- year-old group. tion score. Similarly, the correlation between age The correlations between canine wear scores and the anterior score was low (p - .252, ; = 3.152, and posterior wear scores were statistically signifi- df = 146, F < .01). The correlation between age and cant only until 40 to 49 years of age (Tables 9 to the laterotrusive score was moderate (p = .457, í - 11) and then the correlations disappeared. Be- 6.210, df = 146, F < ,0001]. The correlation tween age 20 to 49 years, canine wear explained between age and the niediotrusive score was statis- 20% to 34% of the total posterior wear (p'), 20% tically insignificant (p = .100, t = 1,219, df ^ 146, P to 29% of laterotrusive wear, and 6% to 36% of < .300). Age (between 19 and 72 years), therefore, mediotrusive wear. explained 6,4% (p-) of the anterior attrition score and 20,9% of the laterotrusive attrition score. Descriptively, both the median and mean rank Discussion of the total attrition scores increased with age (Table 1, Fig 2), However, the median total and The overall findings of this attririon study indicate the anterior attrition scores essentially plateaued to that the contribution of normal aging and the

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Table I Total Attrition Scores with advancing age in both primitive societies"''" Age ¡y) Median Mean rank n and modern societies.""" Direct estimates of func- 20 to 29 31 62,56 tional attrition rates are also available and average 30 to 39 33 74,40 about 50 |.im per year for the posterior teeth.''•*•'''•-•' 40 to 49 32 76,86 These rates are somewhat dependent on the specific 50 to 59 36 92,00 tooth,' and they gradually reduce over time due to 60 to 72 44 123 33 12 the increase in occlusal contacts,"" which affects the depth of wear and volumes of loss."This causes a proportional decrease in force per unit of surface area due to a proportional increase in the base area Table 2 Antenor Attrition Scores and a proportional decrease in vertical height," Subiects who brux heavily would show faster .Age (y) Median Mean rank n rates of attrition than subjects who brux less, but 20 to 29 8 69,26 79 static cletiching would not appear in attrition stud- 30 to 39 7 62 90 50 ies. Longitudinal comparison of the wear rates 40 to 49 8 69,69 21 between known heavy bruxers (from 400 to greater 50 to 59 9 85,59 16 60 to 72 10,5 122,00 12 than 500 pm per year) and nonbruxers (up to 100 |jm per year) indicated that 20% to 25% of attrition is due to chewing,, swallovifing, and other functional tooth contacts, while 75% to 80% is due to parafunction. This estimate of the functional wear Table 3 Mediotrusive Attrition Scores component is similar to the range estimated by rhe Age ¡y) Median Mean rank relation of age to attrition in the present study. However, previous studies did not include other 20 to 29 73,68 79 possible contributors to attrition seventy such as 30 to 39 61,53 20 40 to 49 70,19 21 occlusal geometry. The current study points otit the 50 to 59 77,09 16 expectation for further modification of both func- e0to72 105 63 12 tional and parafunctional wear by the stages of the geometry of anterior guidance and other possible occlusal factors.

Noticeable attrition was already evident in rhe Table 4 Laterotrusive Attrition Scores 20- to 29-year-old group studied, as evidenced by Age !;•) Mediatl Mean rank n median attrition scores, which were 52% of the possible total (see Tables 1 to 4). Much of the clin- 20 to 29 15 58,12 79 ically obvious attrition in adults is therefore esrab- 30 to 39 19 85,50 20 40 to 49 17 82,48 21 lished by 20 to 29 years of age. The literature 50 to 59 19 97 09 16 points out that the severe attrition levels seen in 60 to 72 23 119,92 12 very young populations cannot be explained by the known rates of functional wear.''^•'"••' Dentin exposure and major loss of crown height is described as already common in children and teenagers""--^'" and young adults/'"'"-"-^*-^'-^^ geometrj' of canine function should be included in the evaluation of posterior attrition and that not The presumed rate of wear preceding rhat in the all wear can be attributed to parafunctional habits. 20- ro 29-year-old group was nor maintained (see Tables 1 to 4, Figs 2 and 3), Thereafter, rhe rate of attrition slowed, if not plateaued, through the Pattern of Attrition by Age young adult period, except for the rate corre- sponding to larerotrusive conracr, which did not In the present study, age is considered to be a proxy plateau until the 30- to ,î9-year age range (Table for functional wear. The results show that an age- 4). Since wear did not progress hnearly with age, it related component makes a larger contribution to must he recognized that the existing cumulative laterotrusive attrition (20,9%) than to anterior record of atrrition does not predict the subsequent toorh wear (6.4%) or to mediotrusive attrition (not rate of arrrition (Tables 5 to 8). This may have Significant] (see Tables 2 and 4), Indirect evidence important clinical bearing on the expected wear for an increase iti attrition severity with age is plen- and success of a planned prosthodontic reconstruc- tiful. The prevalence of dentin exposure increases

Journai of Orofaciai Pain 269 Selig man/Pulli nger

- Total altrition score -•- Laterotrusive attrition score

40-49

Age (years)

Fig 2 Median attrition scores for each 10-year age range for total attrition and laterotrn- sive attrition. The potential range for totral attrition was 0 ro 60, and the range for lat- erotrusiue attrition was 0 to 32,

• Totai attntion score •- Laterotrusive attrition score

40-49

Age (years]

Fig 3 Median attrition scores for each 10-year age range for anterior attrition and mediotrusive attrition. The potential tange for anterior attrition was 0 to 12, and the range for mediotrnsive attrition was 0 to 16.

270 Volume 9, Number 3, 1995 Seligman/Pullmger

Table 5 Differences^ in Totai Attrition Scores by Age

Age (y) 30 to 39 40 to 49 .^0 to 59 Ó0 to 72 20 to 29 2- 1 09 z= 1.27 ^=^61 z - 4.41 NS NS 30 to 39 z = 0 22 z= 112 z - 3,23 NS 40 to 49 NS z= 1.08 z = 2.75 50 to 59 NS z - 2.48

"P< 05 "P<.01 "*P< .OOi tMann-Whitrley U test NS = nol 5,gniircant.

Table 6 Differences^ in Anterior Attrition Scores by Age Age (y) 30 to 39 40 to 49 50 to 59 60 to 72 20 to 29 z = 0.79 z = 0.59 z = 1.52 z = 4.18 NS NS NS 30 to 39 z = 0.30 z- 1 45 z = 3.33 NS NS ». 40 to 49 - - z = 0.95 z = 2.11 NS .. 50 to 59 - - 2 = 348

-P •: .05 "Pi .01 "*P<.001 tMann-WhftfleyUtest NS = rot sigflificant

Tabie 7 Differences^ in Mediotrusive Attrition Scores by Age Age (y) 30 to 39 40 tn 49 50 to 59 60 to 72 20 to 29 z = 0.36 z-0.21 z = 2.52 NS NS * 30 to 39 z = 0.65 z= 1 18 z^2.61 NS NS •* 40 to 49 - z = 0.55 z - 2.0S NS - 50 to 59 - - J = 1.69 NS

*P Í .05 "Pi .Oi tMarn-Whitney L/test NS = not sigr I (leant.

Table 8 Differences' in Laterotrusive Attrition Scores hy Age Age(y) 30 to 39 40 ro 49 50 to 59 60 to 72 20 to 29 z - 3 65 z= 1.50 2 = 342 z-430 NS *** ... 30 to 39 z - 0.34 z = 0.88 z = 2.72 NS NS .. 40 to 49 _ z - 1.03 z - 2.30 NS • 50 to 59

•P < .05 -P< .Oi "•Pt .OOi tMarin-Whitney Litest NS = not significant.

Journal of Orofacial Pain 271 Seligman/Pullinger

Table 9 Correlation Between Canine Wear and Mediotrusive Posterior Tooth Wear^

Age df (PI-Pi)' P t P< 20 to 29 77 62.200 .243 2 20 05 30 to 39 18 527 .B04 3.21 .01 40 to 49 19 830 .461 2.26 05 50 to 59 14 510 .249 0.9B NS 60 to 72 !0 140 .510 1.88 NS

p alion coefficient NS = nol signiticant.

Table 10 Correlation Between Canine Wear and Laterotrusive Posterior Tooth Wear^

Age df (pi -Pi)' P Í P<

20 to 29 11 43,034 .476 4.75 .001 30 to 39 18 620 .534 2.68 02 40 to 49 19 847 .450 2.20 05 50 to 59 14 532 .218 0 83 NS 60 to 72 10 195 .320 1 07 NS

tSpearman S rank coi'^elation coefFicienl NS = nol Significant.

Table 11 Correlation Between Canine Wear and Total Posterior Tooth Wear^

Age àf (P>'P.)= P t P< 20 to 29 77 45,132 .451 4.43 .001 30 to 39 18 555 .583 3.04 .01 40 to 49 19 819 .468 2.31 05 50 to 59 14 523 231 0.89 NS 60 to 72 10 157 449 1.59 NS

tSpeannan's rank con-dahon co&^'C NS = nol significan!

tion of missing or carious dentition, and may be tion and total wear. Separate from examination of much slower and more favorable than the present- age effects, canine wear explained 20% to 34% of ing attrition leads to believe. the total posterior attrition (Tables 9 to 11). Of For purposes of future study design, the authors interest, the contribution to mediotrusive wear was conclude that longitudinal study of attrition delayed, presumably until there vvas sufficient requires more than a 20- to 30-year period if dif- canine wear to permit contralateral contact. Mean- ferences are to be discerned by using nonparamet- while, the relationship of ipsilateral (laterorrusive) ric severity scales rather than direct measurement. wear to canine attrition was already strong in the The exception was that early laterotrusive attrition 20- to 29-year-old group, presumably representing in the 20- to 29-year-old group occurs rapidly the natural progression from canine guidance to enough for differences to be measured after only group function described in young adults.' Wear is 10 years (Table S). thus a multifactorial problem explained by simple factors of geometry in addition to parafunction, including possibly crowding, occlusal slides, dual Relationship to Occlusal Geometry bites, crossbites. Angle's classification, as well as The geometry of the contact relationships of the functional chewing habits, and diet. dentition may be as important as functional and Anterior attrition permits functional contacts in parafunctional factors in determining the distribu- the posterior teeth that would not have been other-

272 Volume 9, Number 3, 1995 Seligmsr)/Pullinger

wise possible,-'^" Progressive attrition allows for ble stage) as wear continues in group function (Fig increasingly generalized contact to occur with pro- 2), Over the next 30 years, changes in sleep pat- trusive and laterotrusive mandibular movements terns plus a broadening of facets reduce the fre- and is a major determinant of m,i.\imuni intercus- quency and effects of parafunction, so the gradual pation (intercuspal position)," Attrition itself en- increase in wear scores, particularly in laterotru- courages additional attrition by the body's natural sion, are thought to more clearly reflect functional avoidance of single tooth contacts and the seeking wear. The rate of functional wear ui adulthood out of movements that will .lUow for the greatest remained quite low and was not statistically differ- nLimber of contacting surfaces, '•'" ent from the 20- to 29-year-old group until greater Evidence that posterior attrition is enhanced than 59 years of age (final stage). by canine attririon was seen in our study. Canine The clinical implications of this model would wear explained between 20% and 347u of the pos- suggest that observation of severe attrition in adults terior wear scores between tbe ages of 20 and 49, is a largely cumulative record and may not refer to Others have also fotind greater attrition in subjects an ongoing phenomenon. Invasive treatment for without canine-protected occlusion," and in sub- supposedly heavy bruxism may therefore be redun- jects who had Class 111 malocclusion with reduced dant if the current activity only relates to slow canine-protected occlusion."' Shupe et aP- found functional wear. that subjects with canine-protected occlusion had reduced occlusal forces in tbe posterior teeth, which might explain some of the reduced wear. Future Directions There is usually an inexorable progression from Research is needed to validate the proposed multi- canine-protected occlusion in adolescence to group facrorial etiology of attrition and the proposed function in adulthood.' However, group function model of the pattern of attrition over time. also predominates in young subjects without Because canine attrition contains a component of notable attrition, so this occlusal scheme is not nec- age-related wear, it would be inappropriate to sum- essarily the outcome of severe wear,'' Nevertheless, mate the contribution of age (functional wear) with by adulthood, group function with broad occlusal canine wear on posterior teeth wirhout a complete faceting is typicai, while canine-protected occlu- multiple-regression study. However, it can be esti- sion, round occlusal surfaces, and one-to-one tooth mated to be between a bigh of 54% and a low of relationships are rare,''=-^''' Because anterior teeth 20%, according to this study. By corollary-, the con- are the first to show notable attrition,'"-'"-^'-^"'-'' tribution by factors other than age and the geometry some of the later posterior attrition is certainly a of canine wear is between 46% and 80%. Thus the direct result of the reduced canine protection. decision tree for evaluating the etiology of attrition Barrett-" and Murphy^" botb described an attri- in a patient must include all possible factors, A tion progression in aboriginal Australians, wbo restricted indictment of parafunctional habits is inap- show a progression in dental faceting from anterior propriate, unless it is shown in a multiple-regression analysis that all other possible factors, sucb as age to laterotrusive posterior, and finally to medio- and canine attrition, can be excluded. According to trusive posterior wear. This agrees with our own the present study, this is extremely unlikely. finding that mediotrusive posterior attrition ap- pears to lag laterotrusive posterior attrition by Many other factors have been shown to increase about 10 to 20 years, attrition rates, and these include recent dental A model composed of four stages is proposed restorations,'"-^' tough diets,""" male gen- for attrition progression in modern society (see jgj.^í.,ii,ií,is,rj,2i,2! soi^e occupations,'- some psychologic Figs 2 and 3). Initially as the teeth first erupt, steep factors,'- and the strength of individual bite force,'^ anterior guidance prevents posterior attrition Saliva acidity has been sbown to be both associated-" despite parafunctional and other influences, bur and unassociated"-*" with dental attrition. Future anterior attrition proceeds faster than would be research should elucidate the impact that each of expected by oniy functionai wear. Once the re- these factors has on individual attrition rates. duced anterior guidance permits posterior tooth contact in excursion movements, parafunction and Limitations of the Study other effects accelerate the number and severity of attrition facets (rapid attrition phase). By age 20 to The study population deviates from a general urban 29, attrition has slowed in most areas of the mouth sample with respect to benign temporomandibular (Figs 2 and 3), except for moderate increases in lat- disorder (TMD) signs and symptoms. Because of the erotrusive faceting, until 30 to 39 years of age [sta- continuing belief by the general profession tbat attri-

Journal of Orofacial Pain 273 Seligman/Pullinger

tion and bruxing are potent etiologic factors in 7, Pullinger AG, Seligman DA, Solberg WK, Temporo- TMD, subjects vi'ith any TMD symptoms or signs mandibular disorders: Part 1, Functional status, dento- were eliminated. This was done in spite of the fact morpbologic features, and sen differences in a non-patient population, J Prosthet Dent 1988;Í9:228-235, that virtually no ,is5ociation Is shown between atrri- 8, Richards LC, Brown T, Dental attrition and degenerative tion and TMD symptoms and disease,"'"' arthritis of tbe temporomandibular joint. J Oral Rehabii This cross-sectional study speaks to general 1931:8:293-307, trends and not tn individual variation or prediction 9, Kieser JA, Groeneveld HT, Presión CE, Patterns of dental of the influence of age to attrition severiry in ii par- wear in the Lengua Indians of Paraguay, Am J Phys Aiirbropol 1985;â6:21-29, ticular individual. In this large sample, three sub- 10, Molnar S, McKee JK, Molnar IM, Pryibeck TR, Tootb jects older than 50 years were among the 25% with wear rates among contemporary Australian aburigines, J the least attrition, and 20% of the quarrile wirh the Dent Res 1983;62:562-565. most atrrition were younger than .30 years. Thus, 11, Altpata ES, Molar tooth attrition in a selected group of on an individual basis, some people will maintain a Nigerians, Community Dent Oral Epidemiol 197S;3:132- 135, very low level of dental wear throughout their lives, 12, Poellman L, Berger F, Poellman li. Age and dentai abra- and others will show very high levels early in life. sion. Gerodontics 1987;3:94-96, This study employs established methodology for 13, Woda A, Gourdon AM, Faraj M, Occlusal contacts and ranking dental attrition. However, while the re- tooth wear, J Prosthet Dent 1987;i7:8.';-93, 14, Takenoshita Y, Ikebe T, Yamamoto M, Oka M, Occlusal sults of the analysis are consistent wirh the results contact area and temporomandibular joint symptoms. of prior studies showing a slow increase in cross- Oral Surg Oral Med Oral Pachol 1991;72:388-394, sectional attrition severity over time, che classifica- 15, Salonen L, Hellden L, Prevalence of signs and symptoms tion system may not be entirely linear. The scale of dysfunction in the masticatory system: An epidemio- may allow a rapid rise from a score of 0 (no wear) logic study in an adult Swedish population. J Craniomandib Disord Facial Oral Pain 1990;4:241- to 2 (flattening parallel to rhe occluding planes), 250, hut a change from a score of 3 (flattening of cusps 16, O'Sullivan VR, Power C, Fraher JP. Occlusal wear in and grooves) to 4 (total loss of contour) may medieval Ireland |abstraa 437], J Dent Res 1987;66(spe- require a major increase in observed attrition. cial issue}:IÊl, Thus, a central tendency, with scores of 2 or 3 17, Kampe T, Hannerz H, Strom P, Five-year longitudinal recordings of functional variables of the masticatory sys- much more common than the other scores, was tem in adolescents with intact and restored dentitions: A basically assured. Ihe correlation of medians ro comparative anamnestic and clinical study, .\cta Odontol means was high (p = .89, P < ,001), indicating a Scand 1991:49:239-246, normal distribtirion of the medians around the 18, Hugoson A, Bergendal T, Ekfeldt 1, Helkimo M, means, with rhe central tendency summarized by Prevalence and seventy of incisai und occlusal tooth wear in an adult Swedish population ¡abstract 1792], J Dent borh rhe medians and the means. The broad scor- Res 1988a;67¡special issiie)i337, ing range (0 to 60) also allowed for a reasonable 19, Hugoson A, Bergendal T, Ekfeldt A, Helkimo M, separation in individual variarion and encourages Prevalence and severity of incisai and occlusal tootb wear the continued use of this classification system. in an adult Swedisb population. Acta Odontol Scand 19ä8b:46:255-265. 20, Ekfeldt A, Hugoson A, Bergendal T, Helkimo M, An individual tootb wear index and an analysis of factors corre- References lated to incisai and occlusal wear in an adult Swedish population, .-^cta Odonrol Scand I990;48Í343-349, 1, Brace CL, Occlusion to the anthropological eye. In; 21, Fgermark-Eriksson 1, Carlsson GE, Magnusson T, A long- McNamara JA Jr ¡ed¡. The Binlogy nf Occiuüal term epidemiologic study of the relationship between Development, Ann Arbor, MI; Center for Human Gmwth occlusal factors and mandibular dysfunction in children and Development, 1977:179-209, and adolescents. J Dent Res 1987;é6;67-71, 2, D'Amico A, Functional occlusion of the natural teeth of 22, Akpata ES, Winter PJ, Replication of human occlusa! man, J Prosthet Dent 1961;11:8S?-9J5, tooth attrition surfaces for scanning electron microscope 3, McAdam DB, Tooth loading and cuspal guidance in study, J Oral Rehabii 1991;18:61-67, canine and group function, J Prosthet Dent 1976;35: 23, Agerberg G, Bergenholz A , Craniomandibular disorders 283-290. in adult population of West-Bothnia, Sweden, Acta Odon- 4, Xhonga FA, Bruxism and its effects, J Oral Rehabii tol Scand 1989:47:129-140, 1977:4;é5-7Ê, 24, Von Roulet JF, Mettlet P, Friedrich U, Studie über die 5, Lambrechts P, Braem M, Buylsteke-Wanters M, Vanherle Abrasion von Komposits im Seitenzahnbereicb—Resultate G, Quantitative in-vivc wear of human enamel. 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Resumen Zusammenfassung

El Grado Hasta el Cual la Atrición Dental en la Sociedad Zahnatttition in der modernen Gesellschaft als Funktion Moderna es una Función de la Edad y de los Contactos des Alters und des Eckzahn kontaktes del Diente Canino Bei 146 asymptomatischen Probanden wurde die Zalin- Ei grado de atrición déniai fue corre i ación a do con ia edad como attrition—eingeteilt in eine vaiidierte Skaia—ais Annalierung für un agente de desgaste funcional en 148 personas asintomáti- funktionelle Abnüt2ung mit dem Alter der individúen korreliert. cas, de acuerdo a una escaia de severidad uaiidada. Se anaiizô Der Schweregrad der antenoren, postenoren, mediotrusiven, la- la severidad de la atrición anterior, posterior, en protrusiva terotrusiven und totalen Attrition wurde beurteiit. Der media, en laterotrusión, y totai. También se eiaminó ia contribu- geometrische Anleil der Eck^aiinattntion an der Veränderung ción geométrica de ia atrición canina a ia vananza de la atrición der posterioren Attrition wurde durch Korrelation getestet. Es posterior, por medio de correlaciones al igual que el periodo de wurde die Zeitdauer ermittelt, in der ein statistiscii signifikanter tiempo requendo para registrar una diferencia estadísticamente Unterschied in der Attntion aufgezeichnet werden konnte unter significativa en la atrición utilizando la escala. La edad sirvió Anwendung der Skaia, Das Aiter erkiarte 12,6% der como explicación para el 12,6% de las diferencias en los resul- Unterschiede der totalen (P < 0,001, Spearmans Ftho), 6,4% tados de atrición totai (P < 0,001, rho de Spearman), ei 6,4% der anterioren (P •: 0,01 ) und 20,9% der laterotrusiven Attrition de ios registros anteriores (P < 0.01), y el 20.9% de los reg- (P< 0,000i) ) Die Eckzahnabnjtzung erklärte bei den 20- bis istros de laterotrusión CP < 0,0001), En ei caso de los su)etos 49-jâhriger Probanden zwischen 20% und 34% der posterioren de 20 a 49 años de edad, el desgaste del canino se considero (P < 0,05 bis P < 0,001), 6% bis 36% der mediotrusiven (P < fue el motivo del 20% al 34% de la atrición postenor (P < 0,05 a 0,05 bis P< 0,01) und 20% bis 29% der laterotrjsiven Attrition P< 0,001), del 6% al 36% de la atrición protrusiva media ÍP< (P < 0,05 bis P < 0,001) Mindestens 20 bis 30 Jahre waren 0,05 a P< 0.01 ) y dei 20% ai 29% de la atrición en laterotrusión nötig, um klinische tjnterschiede feststelibar werden zu iassen, (P< 0,05 a Pí 0,0011 Se determinó que como mínimo de 20 a ausser dass Veränderungen der laterotrusiver Attntion in der 30 años eran necesarios para mostrar diferencias ciinicas signi- Gruppe der 20- bis 29-jâhrigen schon nach 10 Jahren aus- ficativas, excepto que ios cambios de ia atrición en iaterotrusión gemacht werden konnten. Nennenswerte Attrition war in der podían ser distinguidos en sólo 10 años para el grupo cuyas Gruppo der 20- bis 29-)áhrigen feststeilbar, wohingegen edades oscilaban entre ios 20 y 29 años de edad. Us personas schneiiere Atlritionsraten in der Gruppe der unter 2O.|ahrigen an de 20 a 29 años de edad ya presentaban una atrición notable, den wenigsten Stelien der Dentition geseher wurden. Man pero los porcentajes de desgaste acelerado antes de los 20 beobachtet eine rightlineate Progression mil dem Alter, womit años de edad, no se mantuvieron en la mayon's de ias áreas de eine Voraussage der zukünftigen Attrition aufgrund der schon la dentición. Se observó que la progresión no era lineal en erfoigten nicht mogiich ist. Attntion hat eine multifaktorieile relación a ia edad, por io cuai no permitió ia predicción de una Aetioiogie, in der das Alter und die Geometrie der atrición subsecuente a los niveles anteriores. Se conciuyó que Eckzahnfübrung, zusammen mit der Parafunktion, eine sig- la atrición tiene una etiologia muitifactoriai, y que la edad y ia nifikante Rolle spielen. qeometría de la guia canina tienen una infiuencia significativa, ademas de las parafunciones comúnmente aceptadas.

Journal of Orofacial Pain 275