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Dental Tribune Middle East & Africa Edition | May-June 2015 33aesthetics > Page 34 Midline diastema closure with direct-bonding restorations By Dr. Sushil Koirala, Thailand M idline diastemata (MD) are spaces of varying magnitude between the crowns of fully erupted maxil- lary and mandibular central in- cisors. Keene describes MD as anterior midline spacing greater than 0.5 mm between the proxi- mal surfaces of adjacent teeth. Incidences of maxillary and mandibular MD are 14.8 and 1.6 %, respectively.1 MD can occur in temporary, mixed or permanent dentition and may be considered nor- mal for many children during the eruption of the permanent maxillary central incisors. When incisors first erupt, they may be separated by bone and the crowns incline distally because of the crowding of the roots. With the eruption of the later- als and permanent canines, the MD reduces or even closes com- pletely. Etiological factors The etiological factors of MD are described by various research- ers. Angle concludes the pres- ence of an abnormal frenum to be the cause of MD,2 a view that has been supported by other re- searchers.3–5 According to Tait, the frenum is the effect and not the cause of the incidence of diastemata.6 He reports causes such as ankylosed central inci- sors, flared or rotated central incisors, anodontia, macroglos- sia, dento-alvolar disproportion, localised spacing, closed bite, facial type, ethnic and genetic characteristics, inter-premaxil- lary suture and midline pathol- ogy. Weber lists the causes for spacing between maxillary in- cisors as the result of high fre- num attachment, microdontia, macrognathia, supernumerary teeth, peg laterals, missing later- al incisors, midline cysts, habits such as thumbsucking, mouth breathing and tongue thrusting.7 Therefore, the etiological factors can be summarised as follows: 1. developmental: microdontia, missing laterals, mesiodens, macroglossia, macro hyper- trophic fibrous frenum; 2. pathological: midline cysts, tu- mours and periodontitis; 3. neuromuscular: oral habits, such as tongue thrusting during speech, swallowing or abnormal pressure during rest. Clinicians must be prepared for patients visiting the dental office with the aim of having their di- astema closed in order to fulfil their psychological (aesthetic and beauty enhancement), func- tional (pronunciation of ‘f’ and ‘s’ sounds and cutting foods with anterior teeth) and/or health (oralhealth maintenance) prob- lems. Treatment options for diastema closure Treatment modalities depend on the etiological fac- tors and complexity of the MD. It is suggested that treatment of a MD should be delayed until the eruption of the permanent canines. However, the patho- logical causes should be ruled out and treated at an early stage, for example extraction of supernumerary teeth (mesi- odens) and surgical treatment for the removal of midline cyst, tumour and periodontal pa- thologies. Surgical, orthodontic (comprehensive/short term), periodontal, directbonding and indirect restorations are the treatment modalities that can be used alone or in combination to achieve harmony in terms of a patient’s aesthetics, function and health. MICD by definition is “a holistic approach that explores the smile defects and aesthetic desires of a patient at an early stage and treats them using the least in- tervention options in diagnosis, treatment and maintenance technology by considering the psychology, health, function and aesthetics of the patient.”8 The MICD concept as the profession- al movement that encourages all clinicians to select diagnosis, treatment and maintenance mo- dalities that are the least inva- sive in order to preserve healthy oral tissues while still achieving the natural aesthetics outcome in the best interests of the pa- tient’s health and happiness. Following, I will demonstrate the clinical use of MICD TP (minimally invasive cosmetic dentistry treatment protocol) to close or reduce the diastema in clinical practice (Fig. 1).8 The direct-bonding procedure with the application of the Flowable Frame Technique (FFT) is pre- sented here as a special tech- nique.9 Case presentation A 20-year-old female patient presented with the complaint that she did not like her smile because of the large gap be- tween her upper front teeth. The patient was very concerned about her smile aesthetics and also aware of her speech diffi- culties. Phase I: Understand In the first step of Phase I, the patient’s perception, lifestyle, personality, and desires were explored in a personal inter- view and through completion of the MICD self smile-evaluation form. The patient, who exhib- ited a high dental IQ, evaluated her smile as below satisfactory. After the interview, the disease, force element and aesthetic de- fects of her smile were explored Fig. 1. MICD TP. Fig. 2. Placement of plastic strip. Fig. 4. Injection of flowable resin to create frame. Fig. 3. Plastic strip is supported with index finger. Fig. 5. Flowable resin ready for light curing. Fig. 6. Plastic strip is removed after light curing; note beautiful lingual frame. Fig. 8. MD in close-up view. Fig. 10. Light touch upon the enamel surface of tooth #12 with diamond point to enhance bonding process. Fig. 7. Lips at rest; note MD is clearly visible. Fig. 9. Teeth #12 and 21 after isola- tion with gingival retraction cords. Fig. 11. Enamel etching with phos- phoric acid (FL-Bond Etchant) for 20 seconds.