Green teeth are an extremely uncommon abnormality that can affect both primary and permanent teeth. When excessive hyperbilirubinemia occurs in the plasma, it causes reversible staining of all tissues except for the teeth (1), because the bile-pigments are permanently trapped due to loss of metabolic activity after maturation. The pigmentation may vary from yellow to deep shades of green (2). It is a cause of anxiety to the family who often visit a dentist to obtain a diagnosis. The management of this abnormality may be complicated (3) and must be a result of a collaboration of a dentist and a physician. This paper reports a case in which green pigmentation of primary teeth is caused by hyperbilirubinemia. This is the first report demonstrating bilirubin levels during the first three months of life of a premature baby, period in which the crowns of deciduous incisors are still forming.
The parents of a 3-year-old Caucasian male child accompanied their son to a dental office due to the presence of green pigmentation on his maxillary incisors. The medical history reported by the parents included that the male infant was born at 27 weeks and 1 day of gestation by Cesarean section and weighted 940 grams at birth. After having contacted the hospital in which the child was born, more information was gathered: the newborn developed a severe respiratory failure due to the respiratory distress syndrome, severe retinopathy of prematurity, grade III peri-intraventricular hemorrhage, bronchopulmonary dysplasia, convulsive syndrome, and he needed gastrostomy due to a deglutition disturbance.
The physical examination focused on general nutritional status as well as on signs of liver disease. Due to the deglutition disturbance, the newborn could not be breastfed (nutritive suction). Up to the fourth month he had been fed exclusively through a nasal catheter and after that a gastric catheter was installed. Due to the prematurity complications, the child exhibited a severe neuro-psychomotor development delay, and, therefore, he needed a special care, nutritional support, physiotherapy and multidisciplinary approach. He had undergone a tetracycline therapy and was continuously using magnesium milk, phenobarbital, cephalexin and vitamins A and D.
Apart from the green teeth pigmentation, an intra-oral clinical examination revealed normal development, no gingival abnormalities, normal texture and color of the oral soft tissues. A normal pigmentation of canines and molars, which were formed 6 months after birth, was observed. The parents reported that the maxillary incisors erupted when the child was 15 months old. They also said that the green pigmentation was present in the crown of the maxillary incisors from the moment they appeared in the mouth (Figure 1). The maxillary incisors are usually completely formed one month after birth. As the pigmentation was present in the maxillary incisors but was not present in the canines, we concluded that what caused the pigmentation had occurred around the infant’s first month of life.
Due to systemic complications, blood samples were collected during the first three months after birth, and bilirubin levels were measured (Figure 2). A dental treatment plan was elaborated after the family had been reassured that the green teeth represented no worries to the present situation of the child because it was caused by a complication that had happened in the past. The parents’ only complaint was the esthetics. There were no symptoms, the child had special needs and was still not mature enough to receive a cosmetic treatment. Therefore, it was decided to have regular checkups every 3 months to maintain oral health with no caries until the teeth exfoliation.
The permanent green pigmentation of dentin tissues as the main alteration caused by hyperbilirubinemia is of interest to the dentist. It is also important to know that jaundice is caused by many disease processes ranging from benign to life threatening (4).
The green teeth pigmentation is an alteration that occurs in the dentin only during its calcification (5), both for primary and permanent teeth (6). The teeth formation stages are already well known, the calcification period for the maxillary central incisors starts at 15 weeks in utero and is completed around one month after birth for males. We can then presume that for the child described in this case, hyperbilirubinemia occurred within this range. However, it was difficult to determine to what extent the bilirubin levels were elevated. There is only an assumption regarding a correlation between various degrees of green staining in the primary dentition and severity of pigmentation (7). Teeth areas that had been calcified after the hyperbilirubinemia period usually show normal color and a sharp dividing line is observed separating the green portion from the normal one. In this case, no line was visible, suggesting a more prolonged period of hyperbilirubinemia (2, 8)
Enamel hypoplasia in both maxillary incisors could have been caused by changes in the organic matrix of the developing enamel resulting from metabolic disturbances, but it is more likely that it is related to the effects of osteopenia and other disturbances of calcium and phosphate metabolism encountered in chronic liver disease (4). Also, this patient had undergone a tetracycline therapy. One of the side-effects of tetracycline is its incorporation into the tissues that are calcifying at the time of its administration. However, the permanent discoloration varies from yellow or gray to brown, but it is never green as it was in this patient. Moreover, during the tetracycline administration for this patient, the primary teeth crowns had already been calcified.
The prevention of all preterm births must be a priority. In this case, the child passed through a prolonged period of hyperbilirubinemia and was born as an extremely premature and underweight baby, which is one of the predisposing risk factors for many abnormalities such as the green teeth eruption in late infancy (9). More common causes of severe indirect hyperbilirubinemia are sepsis, prematurity, blood group incompatibility and G6PD deficiency (9). In the present case, the baby was born very preterm, at a very low birth weight and blood group incompatibility. In cases where the child is capable of receiving a cosmetic treatment, it involves composite resin restorations or transillumination with ultraviolet light aiming at bilirubin breakdown (6).
Most of the reviewed literature consisted of case reports. Further research is needed to provide information on the prevalence, severity, etiology and clinical presentation of green teeth. From this case, we concluded that health professionals should take a multidisciplinary approach when dealing with green teeth and similar abnormalities. There is some evidence to suggest that the patient experienced a period of hyperbilirubinemia during the formation of dental crown and the green pigmentation of the teeth is a rare consequence of neonatal hyperbilirubinemia. Since the green teeth pigmentation is not a common abnormality, families are often frightened and look for a dentist in order to solve the problem. When identifying green teeth, the dentist should be aware of medical causes e should look for a physician in order to establish a final diagnosis. Serum bilirubin levels must be checked in the first months after birth to confirm the diagnosis of green teeth.