By Dr. Glenn M. Gonzales
For its Second General Meeting, the Association of Philippine Orthodontists (APO) was part of the Multi-Specialty Symposium of the 106th Philippine Dental Association (PDA) Annual Convention, held last May 15,2015, at Function room 4 of the SMX convention center.
APO was represented by President-Elect Dr. Martin Reyes, incumbent President Dr. Diana Lim and Past president Dr. Laarni Serraon. Side by side with the Endodontic Society of the Philippines (ESP), the Philippine Pediatric Dental Society, Inc. (PPDSI), the Philippine Prosthodontic Society (PPS), the Philippine Society of Periodontology (PSP) and the Philippine College of Oral and Maxillofacial Surgeons (PCOMS), the APO gave a morning lecture and an afternoon workshop for the convention participants.
Dr. Martin Reyes, for his morning lecture, spoke on “Guided Tooth Eruption : Driftodontics for Correction of potentially difficult Skeletal and Dental Malocclusions ”. Emphasized was the need, in some cases, to start orthodontic treatment before the early adolescent stage in order to prevent a full blown difficult malocclusion from occurring. Early orthodontic treatment during the mixed dentition phase , with the Orthodontist and general dentist working hand in hand through constant monitoring can result in simpler and faster braces treatment once the child patient reaches adolescence.
In the primary dentition, the temporary teeth exist in harmony. There is usually spacing between the teeth. This harmony is disrupted once the permanent teeth start erupting into the mouth during the mixed dentition stage as heralded with the eruption of the 6 year permanent first molars. This is then followed by the eruption of the permanent incisors where, ideally, the temporary canines and molars serve as space maintainers for the soon to erupt perment premolars and canines.
Guided tooth eruption involves 2 procedures, the first being planned serial extraction, followed by driftodontics.
Serial extraction is usually indicated by three criteria. These include a Class 1 Skeletal pattern with a protrusive tendency in the early mixed dentition. Dental crowding should be present, with the patient around the chronologic age of 7 or 8. There is a noted absence of space between the temporary incisors. Advantages of serial extraction include a shorter duration of future braces treatment, accompanied by more stable results. There is also improved lip support, which is particularly true for Filipino Class 1 bimaxillary cases. Unfortunately, serial extraction is not without disadvantages and these include the inability to use this method for all cases. It cannot be done on skeletal Class II and Class III cases. It is best avoided or perhaps performed with extreme caution on deep bite cases.
The sequence of serial extraction can be summed up as CD4 . The C’s ( temporary canines) are extracted first . This allows distal drifting of the permanent incisors, which leads to resolution of their crowding. The D’s (temporary first molars) are extracted next , and facilitates the early eruption of the 4’s (permanent first molars) ahead of the permanent canines. The 4’s are extracted last, and this allows for better alignment of a crowded case.
Some of the effects or consequences of Guided Tooth Eruption includes the phenomenon of Driftodontics where teeth tend to move there are spaces. The anterior teeth tend to drift distally while the posterior teeth tend to drift mesially. There is a reduction in intercanine arch width. Archform also narrows.
Adjuncts that may be used together with Guided tooth eruption are the headgear and fixed lingual arches. The headgear in this case is not necessarily used to move the teeth, rather it holds or maintains the position of the upper first molar, maintaining a Class I molar relationship. Fixed lingual arches can also be used to hold or maintain the position of the first permanent molars.
Dr. Laani Serraon and Dr. Diana Lim facilitated the afternoon APO workshop, entitled “Sharpening your skills on Reading the Panoramic Radiograph for a good Mixed Dentition Analysis”. A short overview on Panoramic x-ray evaluation was provided, followed by the analysis of several panoramic x-rays flashed on the projector screen.
The goal of this workshop is to help participants maximize the amount of information that can be derived from the Panoramic radiograph during the Mixed Dentition stage. It aimed to help sharpen the participants diagnostic skills by pointing out what one needs to look at, what one needs to look for, what it means and what to do. With early detection, both the Orthodontist and the general dentist can work hand to hand to detect and intercept a potentially serious malocclusion.
Space management is a major concern during the mixed dentition stage and one of the most accessible, readily available tools for this is the standard Panoramic radiograph. Compared to a full mouth series of peri-apical radiographs of every tooth in the mouth, the standard panoramic radiograph is relatively practical and reasonable in cost. It is also one of the most common x-rays we request for. With a Panoramic radiograph on hand one the first things that should be done is to count the number of teeth and take note of either the completeness or lacking in number of the teeth. At a glance, many things can be seen from a Panoramic x-ray, which includes the patient’s 1. dental age ( taking note of the resorption of the deciduous teeth, the sequence of eruption and root development of the permanent teeth), the 2. leeway space ( though admittedly it is better to perform a mixed dentition analysis on a diagnostic model cast) and 3. canine development (whether the eruption is ectopic or impeded, which could result in an unerupted impacted canine).
When the patient reaches the chronologic age of 3 all of the deciduous or temporary teeth have finished their development and eruption into the mouth. This is also the age when resorption of the deciduous teeth occurs. Resorption is triggered by pressure from the permanent counterpart. Resorption is considered ideal when the permanent tooth bud is directly underneath the resorbing temporary tooth. Several years after resorption occurs, the mixed dentition stage begins.
To review, the mixed dentition stage or transitional stage or developing dentition stage has three parts. In the first transitional stage the 6 year (permanent) molars and permanent incisors erupt into the mouth. This is then followed by a 2 year lull stage , from ages 8 to 10 years old. This is then followed by the second transitional stage where the permanent premolars, canines and second molars erupt.
Eruption of the permanent teeth can be reasonably predicted by taking note of amount of root development. When the root has reached half of 50% in length, this means it will erupt into the mouth soon. When more than 3/4th or 75% of the root has developed, this means it is about to erupt. This can serve as a guide for predicting whether the extraction of a temporary tooth will either delay or hasten the eruption of its permanent counterpart.
Orthodontic management of the mixed dentition , as mentioned previously, revolves around space management. It includes intercepting malocclusion, avoiding secondary malocclusion caused by neglect and the initiation of treatment, with the orthodontist and general dentist working side by side.
For the temporary teeth extractions are to be avoided. Baby teeth need to be saved whenever possible to avoid loss of space. When extractions are unavoidable there will arise a need for either space maintenance ( with the use of a band and loop, Nance’s holding arch, lingual holding arch or transpalatal holding arch ), balancing extractions and compensating extractions.
Early loss of deciduous canines can lead to collapse in arch length with the lingual dumping of the incisors, particularly for the lower teeth. This is because the lower arch is the contained arch. The use of a fixed lingual holding arch will help prevent this. Early loss of a deciduous canine on one side may necessitate the extraction of the contra lateral canine for balance. Early loss of a deciduous second molar can result in mesial drifting of the first permanent molar. This can reduce the space for the permanent premolars.
Space management also involves evaluation of the available space, taking note of anomalies in shape and size, and anomalies in eruption. Radiographs such as the Panoramic radiograph, supplemented with other radiographs when needed, together with prediction charts and prediction formulas such as Go’s mixed dentition analysis help determine the space available and the space required to fit the teeth. Peg shaped laterals, congenitally missing teeth and supernumerary teeth might be indicative of the possibility of the canines becoming impacted. Eruption is deemed ectopic when it is due to the adnormal postion of the tooth. Eruption is considered impeded when the cause is ankylosis, a possible root fragment , etc.
With the short overview lecture finished, an evaluation of several panoramic x-rays followed. Mentioned were the high incidence of impaction when canines are around 30 degrees from the midsagittal plane. Also, that when the Panoramic x-ray , as corroborated with other diagnostic aids, suggests the need for Serial Extraction, that extractions should be done on both the upper and lower teeth and that this should only be done for Skeletally Class I cases.