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The aim of the study was to determine the reasons given for placement and replacement of amalgam restorations in Nigeria and to establish a baseline data from and for Nigeria.

The records of all patients seen at the University College Hospital, Ibadan were perused and all patients that had restorations done between 1979 and 1992 were recalled for re-evaluation and assessment of restorations. This study was carried out between 1991 and 1995 at the University College Hospital, a Teaching Hospital based in Ibadan, Nigeria.

2094 amalgam restorations met the criteria for the study with primary caries accounting for 74.2 Percent (1553 restorations), primary placements accounted for 75.7 Percent , replacements were 24.3 Percent of the replaced amalgam, fractured amalgam constituted 66.00, Secondary caries 11.6 Percent Secondary caries was not the major reason in this study for replacement of amalgam restorations.

Key Words: Amalgam restorations, Nigeria.


Many surveys and studies to find out the reasons given for placement or replacement of amalgam resto- rations have been carried out in various countries. It has been shown that the results obtained from the various studies were affected by national differences1,2 and time when these surveys were conducted, the latter being due to the type of material available at such times.3,4

Criteria for placement and replacement of amal- gam restorations had been studied by various authors in the developed economies5-14, whereas there is dearth of reports for developing countries.15 Incidentally there has been no study on the placement and replacement of amalgam restorations in Nigeria.

Therefore the aim of this study was to carry out a study to provide a result meant for Nigeria since it has been established that there are variations in results obtained from different countries and to establish a baseline study and data from and for Nigeria as well as to find out the criteria given for placement and replace- ment of amalgam restorations in Nigeria and to com- pare the results obtained in this study with other studies.

Controlled, longitudinal prospective studies would be best when studying longevity of restorations, how- ever, it is unrealistic to expect such investigations to exceed 10 years due to many problems that would beset the study.16 It has also been recognized that longevity of restorations may be registered in longitu- dinal, prospective or retrospective studies; or it may be assessed in cross-sectional, retrospective studies of dental records, provided such are available to show the complete treatment performed over many years.17

This study is therefore a retrospective assessment of dental records of regular attenders at the Dental Centre and Dental School, University College Hospi- tal, Ibadan, Nigeria.


The materials used in this study were dental records of patients seen in the School of Dentistry / Dental Centre of University College Hospital, Ibadan, Nigeria between 1979 and 1992. The records of pa- tients chosen were those that had had restorative procedures carried out on one or more of their teeth during this period. The were properly scrutinized and serialized and the final records were based on regular- ity of patients' attendance, in the dental clinic for a minimum period of 5years. All records showing incon- sistencies either in treatment received or irregularity in the clinic attendance were eliminated from this study. Any record showing ambiguity in treatment given or in a particular tooth treated or even in tooth nomenclature were also eliminated.

All the records that were found suitable were recorded serially and the following data recorded for each patient;

Name of patient



Index number

Residential/Contact address

Type of restorative treatments received

Dates when such restorative treatments were received Reasons given for restoration placement/replace- ment.

After elimination of records that were found not suitable for this study, the serial numbers used earlier were still adhered to so as to enable easy tracing of all treatment records. This method ensured that no treat- ment records were missed or mixed up during compi- lation and analysis of the data collated.

The following criteria grouping were adopted

Primary caries Secondary caries Bulk fracture Marginal failure/ditching Dislodged restoration Cervical abrasion Others - attrition, overhanging restoration, frac- tured cusp/s etc.


The records obtained between 1979 and 1992 showed that two thousand nine hundred and twenty eight amalgam restorations were placed but after the screening of the records only two thousand and ninety four amalgam restorations were found suitable for this study. This study involved adult patients whose age at the time of first placement was equal to and above 16years of age.

The distribution of amalgam restorations accord- ing to Black's definition showed that one thousand two hundred and fifty eight (1258) amalgam restorations were Class 1 accounting for 60.08 Percent of the total number of amalgam restorations ; seven hundred and seventy (770) amalgam restorations were Class 2 thus ac- counting for 36.77 Percent of the total restorations while sixty six (66) amalgam restoration were class 5 (3.15 Percent of total restorations). (Table 1)

There were various reasons given for placement and replacement of amalgam restorations but these reasons were compiled and pooled together to make the result a more compact and manageable one in order to enable easy comparison with other result obtained elsewhere (Table 2).

The frequency analysis and distribution according to reasons given for placement and replacement of amalgam restoration showed that placement of amal- gam restorations formed the highest number of the total restorations placed.

Primary placements were one thousand five hun- dred and fifty two (1552) amalgam restorations ac- counting for 75.74 Percent of total amalgam restorations placed while replacement were five hundred and eight (508) amalgam restoration accounting for 24.26 Percent of all restorations. Table 3 gives the summary of results of amalgam restoration.

Recurrent caries was the reason given for replac- ing fifty nine amalgam restorations (2.82 Percent), complete dislodgement of amalgam restorations accounted for 1.3 Percent (27 amalgam restorations) of the total restora- tions placed; eight (0.38 Percent) were replaced because of overhanging amalgam while other reasons made up the rest (1.53 Percent).


Class of restoration###No. of restoration###Percent of total

Class 1###1258###60.08

Class 2###770###36.77

Class 5###66###3.15

2094###100 Percent


Criteria###No. of restoration###Percent of total

Primary caries###1552###74.12

Fractured restoration###338###16.14

Marginal fracture/ defective

amalgam restorations ("ditching")###78###3.72

Recurremt caries###58###2.77

Dislodged restorations###26###1.24

Overhanging amalgam###08###0.38

Others (include cervical

abrasion, fractured cusps, attrition)###34###1.62

###2094###100 Percent


(a) Primary Caries

(b) Fractured Restoration

(c) Marginal Fracture/Ditching

(d) Recurrent caries

(e) Dislodged Restoration

(f) Overhanging Restoration

Others - Cervical abrasion, fractured cusp, attrition



Total number###2094###100 Percent

of restoration

Number of res-###1552###74.12###= 75.74 Percent

torations placed###primary

due to primary###placement caries

Number of res-###34###1.62

torations placed

due to other reasons

Number of restorations



Retrospective study of dental records is also useful in assessing longetivity, placement and replacement of restorations provided such records show the com- plete treatment performed over many years. However, many variables often cannot be controlled in retro- spective studies e.g. brand material used, clinical conditions at the time of treatment and the quality of original restorations placed.16-19

Placement and replacement of amalgam restora- tions was registered using the retrospective method by studying the dental records of regular attenders; al- though a prospective longitudinal study would have been the most ideal, it is, however, unrealistic to expect such investigations to exceed ten years.17,18,20

A total of two thousand and ninety four amalgam restorations were placed and the percentage of amal- gam restorations placed because of primary caries was 74.12 Percent , total primary placement accounted for 75.74 Percent and those that were replaced as a result of several other reasons were 24.26 Percent (1552, 1586 and 508 amal- gam restorations respectively) which contrasted with almost all results from the developed countries pub- lished before now.

The treatment pattern in previous studies showed that the percentage of amalgam restorations placed due to primary caries had national variations ranging from 29 Percent - 69.9 Percent in amalgam restorations placed in an adult population.7,8,9,14,21

However, there are few reports emanating from developing economies that showed a higher figure of caries being the most common reason cited for place- ment and replacement of amalgam restoration.22-25

Comparison of the result obtained in this study with other results showed that a greater percentage of placement procedures is being carried out thus indi- cating an alarming increase in caries activity profile in this environment while previous treatment experi- ence (replacement) is very low; therefore the state- ment that the dentist spends more than half of his time replacing old fillings does not apply to this environ- ment yet.7,13

All the alloys used in this country were imported with no records of the type of alloys used during this period.

Secondary caries as a reason for placement of amalgam restoration constituted 2.8 Percent of all restora- tion placed (59 amalgam restorations) but when con- sidered in terms of reasons for failure of amalgam restoration, it accounted for 11.6 Percent of all replacements unlike in other studies where higher figures were obtained.

Several reports in the literature revealed that secondary caries has been shown to be the major reason for placement or replacement of amalgam of restorations and the results given varied from 50-59 Percent .1-5,7-9,11,14,26,27 whereas in this study the result showed that recurrent caries accounted for only 11.6 Percent of all amalgam restorations.

Although the high-creep amalgam alloys have been associated with ultimate secondary caries formation this has not been the case in this study. The high rate of secondary caries has been attributed to the fact that dentists could mark more than one reason in their questionnaire this has not been the case in this study.1-4

In Nigeria and probably in most developing coun- tries south of Sahara, there is an evidence of increas- ing caries activity due to "imported civilization" due to large scale importation of refined sugars, chocolates and end-products of refined carbohydrates with no corresponding increase in oral hygiene practices and government funding or established policies on pri- mary oral health care. There are no defined policies on fluoridation of drinking water, worse still there is a dearth of proper and adequate portable drinking wa- ter in most towns and villages in Nigeria, thus making it more difficult for fluoridated drinking water to be delivered. Most of the fluoridated supplements with the exception of tooth pastes are not available for large scale public use.

The reasons for the high rate of placement of amalgam restorations may however, be due to over diagnosis of caries especially on pits and fissures and this may be due to reduced understanding and appli- cation of the criteria for diagnosis of carious lesion vis- a-vis placement of restorations by the practitioner. This is in line with what was reported on the wide variations seen in diagnosis of primary caries by clinicians due to subjective interpretation of caries diagnosis.

It is also important that there should be estab- lished, varied, reliable and universally acceptable guidelines which should be specific to minimize subjec- tive interpretation to assist the dentist in making clinical judgment.14

It was concluded that there were 3 important factors involved in placement and replacement of amalgam restorations27,28 namely the proficiency of the operator or the dentist, oral hygiene and patients habits and type of material used.


In Nigeria, the conditions affecting amalgam res- torations are different from those affecting developed countries and this is due to the differences in dietary habits, established government policies on oral health, increasing availability of refined sugar products and the changing lifestyles of people in a developing economy.

This also confirms the fact that caries incidence is increasing coupled with increasing availability of re- fined sugars in the market without a definite corre- sponding primary oral preventive programme policies by the government has led to the alarming increase in the primary placements seen in this study.

There is therefore, an urgent need for increased orientation and re-orientation of patients and the populace concerning oral and dietary habits and a vigorous attempt at caries reduction programs espe- cially from the school age level to avert the dental catastrophe that could arise from this.

Finally there has to be a specific and well defined guidelines and principles for diagnosis and treatment planning especially for primary placements to avoid over diagnosis of caries as this will go a long way in assisting the practitioner in making clinical judgments.


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1 Senior Lecturer Restorative Dentistry, Department of Dentistry, College of Medical Sciences, University of Maiduguri, P.M.B. 1069, Bama Road, Maiduguri, Borno State, Nigeria Consultant Restorative Dentistry, University of Maiduguri Teachin Hospi- tal, Maiduguri, Borno State, Nigeria E-mail: Tel: +2348050400600, +2348062774747 and +2348022825272

Received for Publication: January 7, 2013 Revision Received: March 3, 2013 Revision Accepted: March 7, 2013
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