Colors in Tooth Discoloration

International Journal of Clinical Dentistry ISSN: 1939-5833 Volume 7, Number 1 Nova Science Publishers, Inc.

COLORS IN TOOTH DISCOLORATION: A NEW CLASSIFICATION AND LITERATURE REVIEW

Hamed Mortazavi1, Maryam Baharvand1, and Amin Khodadoustan2

1Associate Professor, Department of Oral Medicine, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran

2Periodontologist, DDS, MS, private practice, Tehran, Iran

ABSTRACT

Purpose: There has been a recent increasing interest in the management of dental staining as shown by the large number of tooth whitening materials appearing in the market. The aim of this review is to search the literature regarding tooth discoloration in order to introduce a new classification in terms of different clinical colors.

Methods: The PubMed database was searched for articles pertaining to the topic between the year 1932 and 2012. The search strategy for PubMed based on MeSH terms was: tooth discoloration, OR tooth discolorations, OR tooth diseases, OR tooth bleaching.

Results: Based on the relevant evidence, it was shown that tooth discoloration can be found in nine different color spectrums: black, brown, blue, green, grey, orange, pink, red, and yellow. Each color may represent various origins, which needs further investigations to be revealed.

Clinical significance: Our new classification based on clinical features of discolored teeth helps clinicians achieve timely diagnosis and avoid inappropriate therapeutic measures.

INTRODUCTION

The aesthetic appearance of teeth has an important role in physical attractiveness of each person. Discoloration of teeth is a more critical factor for many individuals to achieve an aesthetic smile than restoring normal alignment of teeth within their arch [1-3]. According to a recent study by Samorodnizky-Naveh, 37.3% of subjects were dissatisfied with their dental appearance, and tooth color was the main reason for about 90% of them [4]. Therefore, it is crucial for dental practitioners to have an understanding of the etiology and clinical

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Hamed Mortazavi, Maryam Baharvand, and Amin Khodadoustan 18

presentation of tooth discoloration in order to make a diagnosis and select the most appropriate treatment for each case [5].

Normally, teeth composed of many colors and a gradation of colors occurs in a single tooth from gingival to the incisal edge. Because of the close contact of the dentin below the enamel and thinning of the enamel the gingival third of teeth is darker than incisal third. These differences in color may also be related to the thickness and translucency of enamel and dentine. In most cases canine teeth are usually darker than central and lateral incisors. Meanwhile, teeth become darker with age, so younger people have lighter teeth especially in the primary dentition. This discoloration may be caused by the deposition of secondary and tertiary dentine and pulp stones as a physiological senile change. Historically, tooth discoloration has been classified as intrinsic or extrinsic in nature. Furthermore, a third category of "Internalized discoloration" has recently been described (Box 1).

Intrinsic discoloration (ID) occurs following a change to the structural composition or thickness of the dental hard tissues during tooth development (Box2). On the other hand, ID occurs when the chromogen agents are deposited within the bulk of the tooth, especially in the dentine, and are often of systemic or pulpal origin. This classification is divided into six subgroups: 1) metabolic, 2) hereditary 3) iatrogenic 4) traumatic 5) idiopathic and 6) ageing causes.

Extrinsic discoloration (ED) occurs when chromogen agents are deposited on tooth surface or in the acquired pellicle. This classification can be divided into two subtypes: 1) non metallic (direct staining), and 2) metallic (indirect staining).

Internalized discoloration describes the changes in normal tooth color because of dental caries, tooth wearing and gingival recession, cracks and restorative materials. [2,5,6].

In contrast to all previous papers, in this review article we listed tooth discoloration based on their color, which may help understand tooth discoloration and their causes more practically.

LITERATURE SEARCH

The aim of this review was to search the literature regarding tooth discoloration in order to introduce a new classification in terms of different clinical colors. The PubMed data base was searched for relevant articles between the year 1932 and 2012.The following inclusion criteria were used: extrinsic and intrinsic factors in tooth discoloration, chromogenic bacteria and tooth staining, foods and tooth staining, medications and tooth discoloration, salivary parameters and tooth staining, various dental materials and tooth discoloration, systemic disease and tooth discoloration, habits and tooth staining. Exclusion criteria were articles published in languages other than English and those without full texts.

The search concept based on MeSH terms was: tooth discoloration, OR tooth discolorations, OR tooth diseases, OR tooth bleaching. Totally 4371 articles were initially found in PubMed, which their title and abstract were read to find the evidence met our inclusion criteria mostly. Out of the relevant papers, 253 were review articles, 528 were case reports, and the remainders 784 were clinical studies. Different color changes may be found in discolored teeth as follows:

Colors in Tooth Discoloration 19

Box 1. Different types of tooth discoloration [5-9]

Type of discoloration Color produced Intrinsic Metabolic causes Congenital erythropoietic porphyria Red/brown or purple/brown Alkaptonuria Brown Inherited causes Amelogenesis imperfecta Yellow-brown or dark yellow Dentinogenesis imperfect Blue-brown [opalescent] Dentin dysplasia Brown Iatrogenic causes Tetracycline staining Yellow, brown, blue, black or grey Minocycline staining Brown Ciprofloxacin staining Green Fluorosis White, yellow, grey, or black Traumatic causes Enamel hypoplasia Yellow-brown or white subsurface Dentin hypercalcification Yellow, yellow-brown Pulpal hemorrhage products Grey-brown, black-pink Internal resorption Pink Idiopathic causes Molar incisor hypomineralization White- yellow, brown Extrinsic causes Non metallic [direct staining] Tea, coffee, and other foods Brown to black Cigarettes Yellow Cigars Brown to black Plaques/ poor oral hygiene/ chromogenic bacteria Yellow, brown, green Metallic [indirect staining] Iron salts[polyvalent metal salts] Black Copper salts Green Silver nitrate Grey Potassium permanganate Violet to black Stannous Black Nickel Green Cadmium Yellow to brown Iodine Black Internalized causes Developmental defects Enamel hypoplasia Enamel hypocalcification Fluorosis Acquired defects Tooth wear and gingival recession Yellow Dental caries White spots, orange, brown to black Restorations Brown, grey, black


Box 2. Environmental and hereditary causes of generalized intrinsic discoloration of teeth [5,6,8,9,16,21,26,27,37,39]

Environmental Hereditary Prenatal Post natal Only teeth involved Accompanied by

systemic disorders Maternal drug therapy [Tetracycline] Maternal infection Pregnancy toxemia

Drug therapy [tetracycline, fluoride] Hematopoietic disorders Erythroblastosis fetalis, Icterus gravis neonatorum, Sickle cell anemia, thalassemia Infection Measles, Chicken pox, Scarlet fever Nutritional deficiencies

-Amelogenesis imperfecta -Dentinogenesis imperfecta -Dentin dysplasia

-Epidemolysis bullosa -Erythropoietic porphyria -Osteogenesis imperfecta

Box 3. Drugs related to tooth discoloration [5-9, 11, 13, 16, 21, 23, 26]

Ciprofloxacin Pentamidine Clarithromycin Perindopril Co-amoxiclave Propafenone Enalapril Quinapril Essential oil Ramipril Etidronate Terbinafine Fosinopril Tetracycline Metronidazole Trandolpril Minocycline Zopiclone Penicilline

Colors in Tooth Discoloration

Black: Primary and permanent teeth with black-stains are frequently encountered in

schoolchildren with good oral hygiene and low caries rate. As this type of staining contains an insoluble iron salt, ferric sulphide, and high levels of calcium and inorganic phosphor, it has been considered to be a special form of dental plaque. Actinomyces, porphyromonas gingivalis, and prevotella melaninogenicus have been found as the predominant microorganisms involved in black staining [10,11]. However, Saba according to a PCR microbiological study, established the leading role of actinomyces in formation of black staining compared to other microorganisms [12]. The underlying mechanism of bacterial chromogenicity has to be elucidated.


Black discoloration has also been found in people using iron supplements, containing high amounts of iodine, and in iron foundry workers as well. Furthermore, the same clinical manifestations were reported after use of 8% stannous fluoride that was secondary to the combination of stannous (tin) ion with bacterial sulfides. This pigmentation usually occurs in people with poor oral hygiene. The labial surface of anterior teeth and the occlusal surface of the posterior teeth are the most common affected sites [6,9].

A large number of medications may result in dental surface staining (Box 3). Like other tetracycline derivatives, minocycline hydrochloride causes discoloration of dental crowns and roots. Although the real mechanism is unknown, minocycline has been shown to be incorporated into mineralizing dental tissues during tooth formation [7]. In addition to teeth, it induces pigmentation in other tissues such as oral mucosa, nails, skin, and bone. However, only 3% to 8% of long-term users become affected. Several patterns of staining have been noted in the dentition. For example, the root of developing teeth is stained dark black [9]. Other patterns will be described in next parts of this paper .

Various materials used for root canal therapy may induce tooth discoloration, because of un-reacted agents, or corrosion of some components owing to moisture and/or chemical interaction with dentine. As an example, AH26, epoxy resin cement containing bismuth trioxide as a filler and radiopaque material, can lead to black discoloration in teeth after years [13].The same results were also reported by Davis [14].

Blue, Blue- Brown, Blue-Grey, Dark Blue This rare type of pigmentation is usually caused by chromogenic bacteria. Bussell

reported blue teeth discoloration in a 4- year -old boy with Wast syndrome. Further investigations, revealed a moderate growth of pseudomonas aeruginousa, known as a blue stain-producing bacterium usually implicated in chronic respiratory diseases, in swab samples [15].

A blue-brown (opalescent) discoloration of teeth was also seen in patients with dentinogenesis imperfecta (DI). It is a hereditary disorder of dentine in the absence of any systemic problems characterized by abnormal dentinogenesis in primary and permanent dentition. Severity of dental involvement depends on the stage of tooth development, so that Primary teeth are affected more severely, followed by permanent incisors and first molars. The second and third molars are less affected. Three types of DI have been described: type I, is associated with osteogenesis imperfecta (mixed connective tissue disorder of type I collagen), which may cause opalescent primary teeth. Type II or hereditary opalescent dentine affects primary dentition more severely than permanent teeth. A third type of disease is associated with the radiographic feature of shell teeth having enamel of normal thickness, extremely thin dentine, and an enlarged pulp. This type of disease is more common in deciduous teeth [5, 9, 16].

A blue discoloration of dentition, on rare occasions, may be seen in patients with Parkinson's disease [9].


Another pattern of mynocycline staining is presented as a blue-grey discoloration of the incisal three-fourths of crowns in fully erupted teeth. Dark blue dental pigmentation has been reported in tetracycline users as well.

Intra-canal medicaments are used in management of traumatized teeth, inflammatory root resorption, large periapical radiolucencies, and apexification [7]. Despite their therapeutic advantages, some of these agents can discolor teeth if not completely removed from the access cavity. In agreement with this point, Kim reported a blue greyish tooth discoloration associated with triple antibiotic paste containing ciprofloxacine, metronidazole and minocycline [18]

Brown, Dark Brown, Brown to Black, Brown-Grey, Golden Brown Brown stain as a thin, bacteria-free pigmented pellicle usually is observed on the

buccal surface of maxillary molars and lingual surface of mandibular incisors in people who use a dentifrice with inadequate clinging and polishing action [16].

Extensive use of tea, coffee and tobacco products often results in significant brown pigmentation of the enamel. The main mechanism of extrinsic staining of teeth from foods is not fully understood. Some researchers have demonstrated that anionic polyphenols, found in pigmented foods and beverages (e.g. red wine and black tea), interact with cationic salivary pellicles to form thick layers of stained materials on tooth surface [19,20]. On the other hand, it was noted that physical and chemical forces allow pigments to come in contact with and adhere to the tooth surface [21].

The tobacco staining results from penetration of coal tar products on the tooth surface. Smokers usually exhibit involvement of the lingual surface of the mandibular incisors. The degree of staining is not necessarily related to the amount of tobacco consumed, but rather depends on enamel defects the tobacco products adhere to [22]. Staining is also common in smokeless tobacco users.

Brown, brown black and golden brown pigmentation has been reported, as an extrinsic metallic stain, in individuals who use products containing iron, iodine and stannous fluoride, respectively [6,16,23].

Chromogenic bacteria have also been reported in brown and black tooth discoloration, especially in pediatric patients with good oral hygiene [5,6,24].

Chlorhexidine, one of the most current antiseptic mouthwashes, is associated with brown or brown to black staining of teeth. The side effects of chlorhexidine were first described by Flora in 1971 [25]. The pigmentation may be seen only one week to ten days after using and most frequently involves the interproximal surfaces near the gingival margin. An intensive discoloration has been associated with the use of tea and wine simultaneously [9]. Chlorhexidine is adsorbed on the tooth via binding of its positively charged molecules to negatively charged dental surface. Then some cations such as calcium in plaque and saliva promote its slowly release in an active form [16].

Tetracycline can cause brown or brown grey tooth pigmentation. Tetracycline staining was first described in the mid-1950s. After a decade in 1963, United States Food and Drug Administration issued a warning about the use of this antibiotic for pregnant women and young children [16,26]. Urist and Ibsen demonstrated the ability of tetracycline to form complexes with calcium ions on the surface of


hydroxyapatite crystals [27]. Since it can cross the placental barrier, it must be avoided from 29 weeks of pregnancy till delivery to prevent incorporation into the dental tissue. The most critical time to avoid tetracycline for the prevention of tooth discoloration in primary dentition is 4 months of uterus to 5 months post-partum. In the permanent dentition, this period is from 4 months of infancy to approximately 7 years of age [5]. It is noteworthy that there is no association between tetracycline staining and dental caries [16].

Dental fluorosis is the most common cause of intrinsic tooth pigmentation. The negative effects of fluoride on the enamel were first described by Dean in 1932 [28]. Dental fluorosis may arise endemically from natural water supplies, or fluoride containing products. Fluorosis occurs when concentrations of fluoride exceeds 1ppm in drinking water. The severity of pigmentation is age and dose dependent. Both primary and permanent dentitions can be affected [6,16].

Alkaptonuria is an autosomal recessive metabolic disorder. Incomplete metabolism of phenylalanine and tyrosine promotes aggregation of homogentisic acid with a brown discoloration of permanent teeth has been reported in patients with alkaptonuria [29].

Dentine dysplasia type II is an autosomal dominant hereditary disorder that exhibits some features of dentinigenesis imperfecta. Clinically, the teeth have a brown discoloration similar to DI [9].

Molar incisor hypomineralization (MIH) is associated with a brown enamel discoloration. Enamel in incisors and first permanent molars are severely hypomineralized. Hypomineralization is not symmetrical and the appearance of enamel is porous and brittle. The possible causes are: infections during early childhood, dioxin in breast milk and genetic factors [30].

Sodium hypochloride is a bleaching agent without potential for dental discoloration. However, Souza observed a brown pigmentation when NaOCl was combined with chlorhexidine [31].

Green, Green to Blue-Green Chromogenic bacteria have been implicated in green staining, especially on the labial

surface of the maxillary anterior teeth at the gingival third. It is common in children with poor oral hygiene and is more frequent in boys than girls [6,32].

Green staining of the maxillary anterior teeth has also been induced by penicilllium and aspergillus. These microorganisms grow only in alight areas; therefore, anterior teeth are usually affected [16].

Green discoloration of exposed roots of erupted teeth is another pattern of mynocycline staining [9]. Furthermore, a green to blue-green pigmentation has been found in patients using products containing copper and nickel [16].

Green pigmentation in teeth (chlorodontia) may be associated with hyperbilirubinemia. In this condition, bilirubin is deposited in mineralized tissues such as bone and dentine. The primary teeth affected more frequently than permanent dentition. The most common causes of hyperbilirubinemia leading to this type of discoloration are as follows: 1) erythroblastosis fetalis, 2) biliary atresia, 3) biliary hypoplasia, 4) premature birth, 5) ABO incompatibility, 6) neonatal respiratory


distress, 7) significant internal hemorrhage, 8) congenital hypothyroidism, 9) tyrosinemia, 10) 1-antitrypsin deficiency, 11) hemolytic anemia, 12) viral infection, and neonatal hepatitis [9,33-35]. In addition, Swann and Guimaraes reported two cases of green teeth associated with cholestasis caused by sepsis [36,37]. The presence of green discoloration in teeth is an indicator of hyperbilirubinemia, and determine when in life it was occurred [33]. Clinically, the teeth demonstrate a sharp dividing line, separating discolored (formed during hyperbilirubinemia) and normal colored portions (formed after normal concentrations of bilirubin were restored) [9].

Grey, Dark Grey, Grey to Black Grey pigmentation is common in teeth with amalgam restorations. Corrosive

amalgam discolors the dentine by formation of silver sulfide. This type of discoloration is difficult to remove by bleaching, and tends to recur during the time [16,38].

Mercury, lead, and silver nitrate salts used in dentistry can cause a grey staining in teeth [16,39].

Dental discoloration can occur as a result of materials used for endodontic treatments. For example, Day showed that Ledermix, an intra-canal medicament containing demeclocycline-HCl, can induce grey pigmentation if not removed completely from access cavity at coronal level to gingival margin [40]. Davis and Parsons have reported the same discoloration after use of sealer and sealapex, respectively [14,41].

Dental traumatic injuries may create a dark grey discoloration when the blood degradation products are diffused into the dental tubules. In such cases endodontic treatment before or shortly after total pulp necrosis often prevents progression of discoloration [9].

Orange, Orange-Red The orange discoloration is less common than brown or green and was reported in

3% of the population. It usually occurs on the labial surface of mandibular and maxillary anterior teeth at the gingival third [16].

Chromogenic bacteria such as serratia marcescens and flavobacterium have important roles in this type of staining, especially in children with poor oral hygiene [5,16].

Some root canal cements may also have potential to cause tooth discoloration. van der Bungt reported orange-red tooth discoloration after use of Grossman's, zinc oxide/eugenol, and endometasone cements [42].

Pink Trauma-related stains may create a pink to grey discoloration in the teeth. The real

mechanism of color change is not fully understood. Apparently, different colors represent different entities, some of which are related to pulpal damage with subsequent healing, whereas others result from pulpal necrosis [43]. Pink discoloration is usually seen one to three weeks after traumatic injuries because of localized vascular damage [9].


Pink discoloration is a common clinical finding in teeth with internal resorption. This condition is asymptomatic and usually detected through routine radiographic examinations. The pink staining results from accumulation of granulation tissue in the coronal dentine, undermining the crown. Infection and traumatic injuries to the pulp tissue are the main causes of internal resorption as well as orthodontic treatment. Radiographically, there is a punched out radiolucency, which disturb the pulp chamber or root canal space [44,45]. In these cases endodontic treatments should be done promptly, because extension of the defect can lead to a periodontal involvement.

Color change in the teeth can also occur as a result of materials used for endodontic treatments. van der Burgt and davis demonstrated a pink discoloration after use of some root canal cements such as Tubli-seal, Diaket anf Roth801 in the teeth [14,42].

A similar pink or red discoloration has been reported in the maxillary incisors of lepromatous leprosy patients. Since the causative microorganism prefers low temperatures, teeth are involved in selected areas [9,46].

Red, Red-Purple, Red-Brown This type of discoloration has been reported in congenital erythropoietic porphyria

(CEP). CEP is a rare autosomal recessive metabolic disease, with mutation in the gene that codifies uroporphyrinogen-III synthtetase, leading to porphyrin accumulation in urine, skin, bone and dentine [5,47]. CEP is also known as Gnther's disease and was first described in 1911 by Gnther [47]. In these cases, intraoral examination revealed a red-purple or red-brown discoloration (Erythrodontia) in the primary and permanent teeth. Furthermore, under Wood's lamp there was a bright red fluorescence in the teeth [47].

Reddening of the upper central incisors in patients with lepromatous leprosy has been reported by Rundall. This type of discoloration seems to be secondary to infection-related necrosis and the rupture of small blood vessels within the pulp, with deposition of hemoglobin into adjacent dental tubules [46].

A red-purple staining was also found by Tay when root canals were rinsed with 1.3% NaOCl as an initial rinse followed by MTAD as the final rinse [48].

Yellow, Yellow- Green, Yellow-Brown Yellow to yellow-brown discoloration has been observed in amelogenesis imperfecta

(AI), a hereditary condition characterized by various enamel defects such as inadequate deposition of enamel matrix, insufficient mineralization of the matrix and incomplete maturation of the enamel. The estimated frequency of this entity in population varied between 1:718 and 1:14000. There are at least 14 different subgroups, with numerous patterns of inheritance and a wide variety of clinical presentations [5,6,9].

Traumatic injuries to teeth can induce either a resorptive or calcific response. In calcific phase, after an excessive irregular dentine deposition in the pulp chamber, the clinical crown becomes yellow or yellow-brown whereas, the tooth is still vital [49]. This process is called dentin hypercalcification or calcific metamorphosis [6,9].

Several medications can lead to a yellow discoloration in teeth. For example, teeth affected by tetracycline have a yellowish or yellow-brown discoloration, which is


darker in eruption period, but the color diminishes with time [5]. The same appearances were also reported after use of oxytetracycline and ciprofloxacine [8,9].

Yellow-green discoloration was found in patients with erythroblastosis fetalis (because of incorporation of bilirubin in the developing dentitions), sickle cell anemia and thalassemia [due to deposition of blood pigments within the dentinal tubules] [16].

Remaining of intra-canal medicaments such as Iodine-potassium iodide( Iodoform-based medicaments) and UltraCal XS during the endodontic treatments can result to a yellow to yellowish brown staining in the teeth [18,40].

Some habits such as smoking [cigars or cigarettes] or chewing of Khat (Catha edulis) leaves for its stimulant properties may produce yellow-brown dental staining [16].

CONCLUSION

Many color changes can be encountered when dealing with tooth discoloration. Approach to the patient with discolored teeth might be more efficiently accomplished using our new classification based on clinical findings rather than previously etiology- oriented categorizations.

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Colors in Tooth Discoloration