The continuous evolution of materials and technologies used in the practice of pediatric dentistry, the increase in the number of skeletal space maintainers, prefabricated or made by CAD/CAM technology, required the elaboration of an English edition, revised and supplemented with both clinical and technological elements related to dental techniques.

In the meantime, introducing the residency and the specialty of Pediatric Dentistry in Romania, required the development of certain chapters, as well as the broad presentation of the evolution of clinical cases with different types of space maintainers.

We hope that this edition will capture the interest of future English department students, residents, dental technicians and all dentists who passionately care for the oral health of children.

Professor Dr. Habil. Alexandru Ogodescu

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1. INTRODUCTION

Space management is one of the most important themes in pediatric dentistry, given its influence on the growth and development of the stomatognathic system. It is a boundary between pedodontics and orthodontics, which dentists need to understand and apply with clinical sense and tactfulness.

Early loss of primary teeth compromises the eruption of permanent teeth, leading to the appearance of dento-maxillary abnormalities that require subsequent complex, long-lasting and expensive orthodontic treatments.

The space maintainer, a relatively simple therapeutic element, but complex as applicability and follow-up, helps us in the limit situations where, due to the pathology of the root furcation, a primary tooth has to be extracted without compro- mising afterwards the evolution of the dental eruption.

Concerns about pediatric crowns and space maintainers date from the beginning of my teaching career (2000) when, along with two visionary students, passionate about pediatric dentistry, to whom I coordinated their bachelor's degree thesis:

Dr. Emilia Augustinov (Ogodescu ) and Dr. Varga Imola, we were able to apply the first pre-fabricated pediatric crowns and the first fixed space maintainers as band and loop, therapeutic solutions which at that time, in Pediatric-Orthodontic Clinic in Timisoara had only theoretical resonances.

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At present, within the Timisoara Pediatric Dentistry Discipline, the entire teaching staff is currently applying prefabricated pediatric crowns (trying to replace the metal with zirconia, aesthetic crowns) and the entire space-maintaining panoply. The students of the Faculty of Dentistry at the "Victor Babeş" University of Medicine and Pharmacy Timişoara learn, both theoretically and practically, the use of these therapeutic methods, acquiring practical skills that in 2000 we only dreamed about... but taking this dream more further away we can say that today the era of endless sessions of lavation in primary teeth with infected root channels is long forgotten, the primary tooth is treated correctly in a single session, and when restorative therapy fails, an optimal space management is prvided for a undisturbed eruption of permanent teeth. We do not monitor the gangrene anymore, but the evolution of space maintainers and the growth and development of the stomatognathic system in today's children...who are more joyful and more confident.

By performing quality and complex pediatric dental treatments, all dental practitioners who treat children contribute to the decrease of the large number of dento-maxillary abnormalities that we see in current generations, thus contributing to the improvement of their oral health.

Modern diagnostic technologies, current therapeutic and technological possibilities, the emergence of prefabricated space-maintaining systems, the accumulated experience led me to synthesize them along with my colleagues in this book, which we hope will be useful for both dental students and detists.

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2. GROWTH AND DEVELOPMENT OF THE STOMATOGNATHIC SYSTEM:

THE STAGE OF PRIMARY AND MIXED DENTITION

Within the Textbook of Orthodontics, under the editing of Prof. Samir E. Bishara, Robert N. Stanley, a professor at the Iowa Orthodontic Department, human growth is defined as follows: a complex process which cannot be described with a simple definition, it is a game between heredity and the environment, it is dimensional growth and change, which takes place differently and in different rates throughout life (Bishara SE, 2001).

It encompasses human development from a physical, mental, psychological, social and moral point of view (Krogman WM, 1972). Physical growth is a disturbing sequence of events, which converts a cell into an infinitely complex individual (Bishara SE, 2001).

From a biological point of view, growth occurs in both hard and soft tissues, and the interaction between them lies in the center of attention in the research that is being done at present, as well as in the monographs written on this topic, internationally.

In most medical papers, the term "growth" is always accompanied by the term "development". In the OFX 98, the verb "to grow" means to increase gradually, to become larger as a result of the vital processes within the body, to develop (in

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humans, animals and plants or parts of them). The verb "to develop" (about beings) means to evolve, to gradually increase (in a physical sense), to increase (about human beings), to evolve gradually (as regards intellect). The first synonym of the verb "to develop" is the verb "to evolve", followed by the verb

"to grow".

These terms are indeed linked to each other, but they are not synonymous, especially when we refer to them from a biological point of view. Through growth we understand dimensional enlargement and through development we understand evolution, which does not necessarily imply dimensional growth in every sense.

Professor William Proffit, in 2012, states that the term

„growth” is most often used to express dimensional growth or number, while development is an increase in complexity. This may even reflect a dimensional reduction or the disappearance of some tissues in the body. It is well known that a specialization of tissues in performing functions can be done in parallel with dimensional reduction or loss of other functions (reduction of potential at other levels). Thus, we can say that while growth is an anatomical phenomenon, development is a physiological or behavioral phenomenon.

Interesting is Enlow's explanation regarding the terminology. From his point of view, growth is the equivalent of magnitude changes, but it does not imply knowing how the phenomena are occurring. It is in fact a more general term, easy to use by clinicians. But if we ask questions about what is happening and how it is taking place, we need to add the

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descriptive term "development" through which we explain the phenomena. This term has connotations on maturation processes, involving a progressive cellular and tissue differentiation, emphasizing the biological mechanisms that take place during growth (Enlow D et al., 1996).

In the intrauterine life and during the first months of postnatal life, the rate of growth and development is very high.

By the fourth month of extrauterine life, the weight recorded at birth doubles (the first postnatal growth peak is recorded). If the growth process would continue at the same rate, at the age of 50 years old, a man would weigh 450 kg and would be 15 meters tall. During childhood, there are other periods of acceleration of growth (peri-pubertal growth peak).

When we attempt to characterize growth, there are three basic concepts which are to be used: the growth pattern (refers to how the proportions change over time; for example: the normal growth pattern of the body respects the cranio-caudal gradient of growth, and various tissues of the body have a different rate of growth), the variability (it reflects the individuality of each human being; it is important to delimit the normal range of variation, by statistical methods; in this sense it is important to determine the standards for a certain age; the deviation at a given time in the pattern of growth had previously may have pathological significance) and the timing of growth (the same event can take place at different times in each individual, each person has his own "biological clock").

Although we are accustomed to our age being chronologically measured, we all have a biological age, and the inter-individual

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variability in the growth calendar could be greatly reduced if we take into account the latter (Proffit WR et al., 2012).

The factors influencing growth and development are:

genetic, neuroendocrine, nutritional, secular tendencies, the seasons and the circadian rhythm, disease and cultural factors (Bishara SE, 2001).

Only a few decades have made great progress in this area. If we ask ourselves about what to do in the future, it is worthy today to remember the words of Professor Moyers, who expressed his support at the end of his career (1990) for future research in this field: "We have still have important research to accomplish and we face so many challenges in front of us, if we think about the expectations of patients, colleagues and society. I would have liked to be able to take it right from the beginning. "(Mc Namara JA, 2004).

2.1 MORPHOLOGY OF THE DENTAL ARCHES AND DEVELOPMENT OF OCCLUSAL REPORTS DURING GROWTH AND DEVELOPMENT OF THE STOMATOGNATHIC SYSTEM

Dental eruption, dental arches development, and occlusal plane development are processes that are closely related to each other, which are carried out simultaneously during the growth and development of the stomatognathic system. Therefore, the morphology of dental arches and the development of occlusal plane may be theoretically subdivided and studied in the three stages through which dentition passes:

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primary, mixed and permanent. These two processes are also called the dynamics of intra- and inter- dental reports.

The morphology data of the primary and permanent teeth, the morphology data of the dental arch, constantly changing during the growth and the eruption of the teeth, and the evolution of the occlusal reports from the eruption of the first primary tooth to the end of the eruption of the permanent teeth, are particularly important for each dentist.

The dental arch dimensions change with growth;

therefore, it is necessary to distinguish between the changes induced due to treatment with orthodontic appliances and those that result from natural growth. Changes that occur naturally in children that are not orthodontically treated should be characterized by the standard values, which can be used be used in the assessment of the changes that occur during orthodontic treatment.

Stillman analyzed the growth of the intercanine distance both in the upper and lower jaw until the age of 25, and has found that this distance continued to grow in the maxillary arch to up to 13 years of age, and in the mandible to up to 12 years of age, remaining stable afterwards. Boys had wider arches compared with girls (Stillman JH, 1964). Bishara also found the existence of larger transverse dimensions of the boys' arches compared to the girls'. This has led to a significant increase in the maxillary inter-canine distance to boys and girls aged between 3 years and 13 years. Between 13 years and 45 years there has been registered a slight decrease in this distance, but this was only significant for girls aged between 26

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years and 45 years. As regards the mandibular inter-canine distance, this has increased significantly in girls up the age of 13 years and in boys up to the age of 8 years. Afterwards, there was a decrease in this distance, which was significant between 26 and 45 years for both sexes (Bishara SE et al., 1997).

The changes occurring in the dimensions of dental arches between 6 and 18 years were illustrated by Moores in an article published in Am J Orthod in 1969 and have been reproduced by Bishara in the 2001 edition of the Textbook of Orthodontics (Fig. 2.1).

Fig. 2.1 The average changes (in mm) that take place at the dental arches between 6 years and 18 years (Bishara SE, 2001)

These modifications, after Moores, have been also presented in the national literature. Thus, Irina Zetu and Mariana Păcurar describe these changes in the first volume of the book „The Straight Arrow Technique, Necessary Analyzes”

between 5 and 18 years, the dental arch length is decreasing with 2 mm in the upper jaw and 3 mm in the lower jaw, and the perimeter of the maxillary arch increases on average with 1.3

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mm in boys and 0.5 mm in girls and decreases in the mandibular arch by approximately 3.4 mm in boys and 4.5 mm in girls; between 5 and 8 years the anterior width between the canine points increases by approximately 4 mm in the upper jaw and 3 mm in the lower jaw (Zetu I, Păcurar M, 2003).

The achievement of the occlusal reports begins in intrauterine life by establishment of the sagittal reports between the maxilla and the mandible. Subsequently, the postnatal preeruptive stage is characterized by the presence of an anterior open bite and contact of the lateral edentulous ridges.

In most cases, the maxillary alveolar ridge circumscribes the mandibular ridge (Bishara S, 2001). Between 6 and 30 months, primary teeth eruption occurs and the first occlusal reports are established. Starting from the age of 30 months, the functional phase of the dental arches and occlusal reports begins, which extends until the age of 6, and is subdivided into the primary morphology stage of primary dental arches (up to 4 years) and stage of secondary morphology (ranging from 4 years to 6 years) (Bratu E et al., 2005).

From the abundance of parameters that characterize the development of dental arches and occlusal reports in these stages (the morphology of the arches, occlusal surfaces, overbite, overjet, spacing, clogging, primate spacing) and which may be described and investigated through extensive studies, we stopped of the flush terminal plane, which is of particular importance in the establishment of the first permanent molar relationships.

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The flush terminal plane can have three forms, clinically: straight, in mesial step and in distal step. Anderson determined the following percentages in Caucasian children:

60% have a flush terminal plane in mesial step (40% of the children have a flush terminal plane in mesial step under 2 mm and 20% of them have a flush terminal plane of over 2 mm);

30% shall present a straight flush terminal plane and 10% a flush terminal plane in a distal step (English JD et al., 2009).

Mixed dentition is one of the most dynamic periods, dominated by both the development of dental arches and the occlusal reports. From the multitude of aspects that can be researched, we will stop on the possibilities of solving the existing space deficiency due to the dimensional differences between the primary and permanent teeth and the establishment of the occlusal reports of the first permanent molars.

After Baume, detailed rules for the establishment of a neutral relation of the first permanent molars are: closure of the primates spaces (the lower diastema is wider than the upper one) with mesial migration of the two primary molars and the first permanent molar and thus shortening of the lower dental arch; use of the space stock (leeway space), which makes it possible for the permanent molars to migrate mesially; the distal eruption of the first permanent molars, when the maxillary is well developed (Bratu E et al., 2005).

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2.2 SPACE RELATIONS IN THE CONTEXT OF PRIMARY INCISORS REPLACEMENT

The dimensional differences between the permanent incisors and the primary incisors are highlighted especially in the early stages of mixed dentition (Fig. 2.2).

Fig. 2.2 The orthopantomography of a 6 year old patient, in which we can notice the dimensional reports between the permanent and primary incisors (Collection

of the Department of Pediatric Dentistry)

The sum of the mesio-distal dimensions of the permanent superior incisors is 8 mm higher (the size is equivalent to a permanent upper lateral incisor) than the sum of the mesio-distal dimensions of the primary superior incisors.

The mandibular difference is smaller (5-6 mm), which is equivalent to the mesio-distal size of a permanent inferior lateral incisor (English JD et al., 2009).

Regarding the upper jaw, there are some natural compensatory mechanisms for this space deficiency, that occurs during their eruption: the permanent incisors have a more vestibular axis of eruption, and they erupt on a larger

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circumference compared to the primary incisors (this is the most effective mechanism); during their eruption, they exert pressure on the adjacent teeth (it is known as the „pushing effect”), resulting in the gradual closure of the existing spaces between the primary teeth (e.g.: the permanent central incisors exert pushing effects on the primary lateral incisors, and the permanent lateral incisors exert pushing effects on the primary canines); the transverse growth of the maxilla due to the mid- palatal suture. These compensations usually occur and generate a dento-alveolar disharmony with physiological spacing (the well-known „ugly duckling stage”).

When these compensations cannot occur, we encounter dental crowding or crossbite, especially in the maxillary lateral incisors, due to the more palatal localization of the germs of these teeth (English JD et al., 2009).

In the mandible, the compensatory mechanisms are deficient. Only one of the mechanisms presented for the upper jaw is also preserved in the mandible: the pushing effect. The eruption of the inferior incisors does not occur on a more vestibular axis compared to the primary incisors and the transversal growth does not occur at the mandible due to the early closure of the sutures at this level.

When spacing between primary teeth is insufficient (spaces should exceed 5-6 mm), dental crowding is frequently present at this level and is called "dento-alveolar disharmony with physiological crowding" (English JD et al., 2009).

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2.3 SPACE RELATIONS IN THE CONTEXT OF PRIMARY CANINES AND PRIMARY MOLARS REPLACEMENT

The space for permanent teeth that do not have primary predecessors (6-year molars, 12-year molars and third molars) is obtained through the growth mechanisms that occur in the jaw bones: in the upper arch there is a posterior growth in the maxillary tuberosity, and at the mandible there is a bone apposition on the posterior edge of the mandibular ramus and resorption on the anterior edge of the mandibular ramus. These are accompanied by another mechanism: the mesial migration of the first permanent molars, due to the space excess (the well- known leeway space).

Leeway space has a size of 2-2.5 mm in the mandible and 1-1.5 mm in the maxilla. This is mainly due to the dimensional difference between the second primary molars and the permanent premolars, which is 2.7 mm in the mandible (also known as E-space) and 2 mm in the maxilla. To this is added the dimensional difference between the first primary molars and the first permanent premolars, which is 0.9 mm in the mandible and 0 mm in the maxilla and the dimensional difference of the primary and permanent canines that is -1 mm in both arches (Fig. 2.3). The mandibular space stock is about 1.5 mm larger than the maxillary space stock (van Waes H, Stöckli P, 2001).

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Fig. 2.3 The average mesio-distal dimensional reports between the primary molars and canines and the permanent premolars and canines (van Waes H,

Stöckli P, 2001)

During normal occlusal development, the anterior migration of the molars, which is more pronounced at the mandible, uses 2 mm of the leeway space. Physiological crowding in the anterior segment can also be reduced on the basis of leeway space, by distal migration of permanent canines (English JD et al., 2009).

The changes that take place at the dental arches are due to bone growth and dental eruption, but are also due to the occlusal evolution. The eruption of the central and lateral incisors results in an increase in the length of the dental arch,

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and the mesial migration of the molars causes it to decrease. At the maxillary the total length of the dental arch is constant between 3 and 15 years and at the mandible is slightly higher at 3 years compared to its length determined at 15 years (English JD et al., 2009).

2.4 THE SPACE BALANCE

The first step in achieving the optimal space management in primary or mixed dentition is represented by the realization of a correct study model and its analysis.

Elements of analysis include: dental and alveolar morphology, the sequence of eruption and dental age analysis, occlusal reports analysis and occlusal development, achievement of the space balance and to highlight the emergence of possible malocclusions.

The study models are made, especially during the critical period of 6-12 years, at intervals of 1 year. One of the important purposes of conducting study models is to analyze the space in mixed dentition and to highlight the evolution of intra- and inter-arch reports.

Most frequently, orthodontic problems occur where there is an inadequate space for the eruption of permanent teeth.

Early assessment of the available space as well as space required, allows early intervention to prevent the development

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of malocclusion, with no need for subsequent orthodontic treatments, long-lasting, expensive, and with uncertain results.

The objective of space analysis is to answer the following question: is there enough space for the permanent tooth to erupt? Determining the size of the canines and the premolars that have not yet erupted, is an important factor in assessing the child's occlusion.

Performing this space analysis is often indicated in the following situations: premature loss of primary canines:

rotation or obstruction of lateral incisors due to space loss;

ectopic eruption of the first permanent molars; the existence of a cross-bite occlusion, or the existence of a flush terminal plane in distal step.

According to Fields and Proffit (1998), the basic principles of spatial analysis in mixed dentition are as follows:

1. The presence of the first permanent molars and permanent incisors on the dental arch

2. The permanent successors teeth are in the process of formation;

3. There is a relationship / dimensional formula between the permanent teeth that have not yet erupted and the primary teeth;

4. There is a difference in size between canines, primary molars and the permanent successors. The mesio-distal size of canines and primary molars is greater than that of the permanents that will erupt in their place. Nance

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called this space difference "leeway space", which he estimated at 0.9 mm for half the maxillary arch and 1.7 mm for half the mandibular arch.

Nance also proposes in 1947 a conventional space analysis, which compares the amount of the available space (at alveolar level) for the alignment of the teeth with the required space for proper alignment.

The space balance = Available space – Required space

The available space is obtained by measuring the perimeter of the alveolar process, from the mesial side of the first permanent molars from one side of the arch to the mesial side of the other (for example from 1.6 to 2.6).

Fig. 2.4 The available space (blue) always refers to the alveolar process (red) and it is measured midway between the vestibular-oral distance of the alveolar process,

mesial of the two 6-year-old molars (Collection of the Department of Pediatric Dentistry)

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This can be achieved by dividing the dental arch into segments, which can be measured as linear approximations of the alveolar process, or with a piece of pre-curved wire, corresponding to the middle (in vestibular-oral direction) of the alveolar process between the two molars (Fig. 2.4).

The required space is the sum of the mesio-distal dimension of the erupted mandibular or maxillary permanent incisors and the mesio-distal dimension of canines and non- erupted premolars.

The size of the non-erupted teeth can be obtained using one of the following methods:

- Tooth measurement on radiography (retro-alveolar, orthopantomography), calculating the magnification coefficient using of the rule of three;

- Using a prediction table (e.g., Moyers);

- Combining the two methods.

Fig. 2.5 Three-dimensional images obtained with CBCT highlight the reports between primary teeth and their permanent successors

(Collection of the Department of Pediatric Dentistry)

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The latest imagery technology, such as cone beam computed tomography (CBCT), allows a three-dimensional view of the scanned areas, allowing for an extremely accurate dimensional measurement of the teeth to be used in the space balance, as well as an accurate reporting between the dimensions of the primary teeth and those of the permanent successors (Fig. 2.5-6).

Fig. 2.6 The CBCT technology allows a precise dimensional assessment of the teeth to facilitating the achievement of the spatial balance

In the majority of cases, achieving the space balance is based on Tanaka and Johnston's analysis. It is recommended as a predictable technique because it has an acceptable accuracy, does not require radiography, or prediction tables with average values and predicts the average size of canine and non-erupted premolars.

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At the mandible, the sum of the estimated size of the canine and of the two premolars for a mandibular quadrant is calculated by dividing the lower incisive sum (sum of the mesio-distal dimensions of the four lower permanent incisors) into two, plus 10.5 mm.

At the maxillary, the space balance is also calculated using the lower incisors, adding to the half of the incisive lower sum 11 mm.

Mandible: C + PM1 + PM2 = lower incisive sum / 2 + 10.5 mm

Maxillary: C + PM1 + PM2 = lower incisive sum / 2 + 11 mm

The space balance may be negative, indicating a space deficiency, or positive, indicating an excess of space.

Negative space balance indicates the presence of dento- alveolar disharmony with crowding, classified by gravity as follows (Bratu E et al., 2005):

Space deficiency less than 2 mm = slight crowding;

Space deficiency of 2-4 mm = moderate crowding;

Space deficiency of 5-9 mm = serious crowding;

Space deficiency of 10 mm or more = severe crowding.

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Applying a passive space maintainer is only indicated in the case of a space deficiency of maximum 2 mm, while in other cases it is necessary to regain the space. If the space balance is positive, indicating an excess of space in the dental arch, the application of a space maintainer is no longer mandatory.

However, it should be emphasized that neither the conventional analysis nor the Tanaka and Johnston’s method take into account the axial inclination of the lower front teeth, the effects of curve of Spee, the facial profile, the inclination or the facial profile of the different ethnic groups, any of which may affect the crowding value and the necessary space obtained during the analysis, a more thorough assessment of the space and the completion of the specific medical file (Picture 2.7).

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Picture 2.7 The space balance file for mixed dentition designed and used in the Department of Pediatric Dentistry, Timisoara

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3. CAUSES OF SPACE LOSS IN

PRIMARY AND MIXED DENTITION

Space loss in primary or mixed teeth is due either to general causes or to local causes.

Thus, among the general causes we can list:

- endocrine disorders

- the underdevelopment of maxillary tuberosity due to bone formation delays

The local causes are:

- the proximal extended caries

- occlusal and vestibular, untreated caries - nursing bottle caries

- periodontal diseases leading to loss of primary and permanent teeth: localized and generalized aggressive periodontitis

- dento-alveolar trauma

Endocrine disorders (e.g.: hyperthyroidism) cause premature exfoliating of primary teeth, accelerated eruption of permanent teeth, eruption disorders, disturbance of the eruption sequence.

The underdevelopment of maxillary tuberosity due to bone formation delays is associated with a high position of the tooth bud of the first permanent molar, its occlusal surface facing forward.

From its high position, the permanent molar seeks to reestablish its direction, exerting pressure on the roots of the

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second primary molar, which results in a faster root resorption with its loss and the mesial eruption of the first permanent molar.

This phenomenon has been named by Schwarz, Hotz and Reichenbach: undermining resorption, a clinical entity that we can define as pathological resorption by undermining (Fig. 3.1).

Fig. 3.1 Pathological resorption, by undermining of the distal roots of the upper second primary molars (5.5, 6.5), due to the pressure exerted by the upper first

permanent molars (1.6, 2.6)

(Orthopantomography - Collection of the Department of Pediatric Dentistry)

Pathological resorption, by undermining, is an extremely complex clinical entity that requires a careful approach to avoid a loss of space at this level.

Another situation that may lead to early loss of the two primary upper molars is represented by a normally developed tuberosity, in parallel with an early development of the permanent second and third permanent molar, which exert pressure on the first permanent molar and move it mesially, finally causing the early root resorption of primary molars (Picture 3.2).

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Fig. 3.2 The underdevelopment of maxillary tuberosity with ectopic eruption of the second permanent molar and the eruption of the third permanent molar

The proximal, evolutive, extended, untreated caries leads to reduction of the mesiodistal dimension of the primary tooth, thus shortening the arcade and reducing the space required for permanent successors. The proximal caries of a primary first molar with the collapse of the proximal edge and destruction of the distal surface, leads to the mesial migration of the second primary molar and the first permanent molar (Fig. 3.3).

Fig. 3.3 Proximal afront caries in primary molars from quadrant 5 (Collection of the Department of Pediatric Dentistry)

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Proximal caries develop without symptomatology, and the lesion becomes painful only when the marginal edge collapses, allowing the dental papilla to be compressed under masticatory pressures. The child complains of an acute pain, accentuated after meals.

This form of cavity is rapidly spreading in depth, reaching the tooth pulp temporarily. Progression to the pulp may be asymptomatic, leading to necrosis and eventually installing cellulite. Only systematic radiological detection allows the early treatment and preservation of the vital dental pulp of these primary teeth. In this case, at the debut of the lesion, the tooth has a normal coloration, but the dental tissues are deteriorated and dentinal sensitivity is perceptible. The highlighting of the pulp horn is frequent, especially in the first primary molar.

The stationary caries, located on the occlusal, vestibular or oral surfaces, if left untreated, can lead to pulp complications (gangrene, abscess, furcation pathology). The occurence of furcation pathology, confirmed by radiological examination, is an absolute indication for primary tooth extraction due to the risk of damaging of the underlying permanent dental bud (Fig. 3.4).

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Fig. 3.4 Accentuated radiolucent areas at the level of the furcation of right mandibular primary molars: the furcation pathology, Orthopantomography

Uncomplicated pulp disorders should be treated by conservative methods to keep the primary tooth on the arch, as this is the best space maintainer. Pre-fabricated pediatric crowns are an excellent way of restoring primary teeth with large carious destructions, bulky obturations, or with or pulpotomy or pulpectomy.

Nursing bottle caries and rampant caries are two common forms of early childhood caries - ECC (Fig. 3.5, Fig.

3.6). They expand rapidly into the surface and in depth, often involving all teeth, with the unfavorable consequences outlined above. Tooth damage is precocious and occurs right after teeth eruption. The most affected areas are the vestibular and palatal area of the superior incisors, but they can spread to all erupted teeth at a certain time. Thus, the first affected group is that of upper incisors, followed by the first molars, canines and second primary molars. Due to the protection of the soft parts and the vicinity of the submandibular and sublingual glands,

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mandibular incisors are less affected. There are situations where inferior teeth are also affected and the term used in this case is "rampant caries".

Fig. 3.5 Nursing bottle caries with precocious destruction of the primary upper frontal group (Collection of the Department of Pediatric Dentistry)

Fig. 3.6 Rampant caries with massive coronary destructions involving all primary teeth (Collection of the Department of Pediatric Dentistry)

Trauma of primary and permanent young teeth occurs primarily on frontal teeth. In young children, due to the resilience of the alveolar bone, the most common forms of trauma are intrusion, partial and total luxation, crown and root fractures being less common.

Intrusion is the result of a shock directing the tooth in apical direction. The upper front group is most affected.

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Immediate replacement, or expectancy attitude until spontaneous repositioning of the tooth, are the two therapeutic alternatives.

Partial luxation is the result of an antero-posterior shock with frequent interposition of an object. The spontaneous recovery of the tooth is observed in most cases. Total luxation (=avulsion) is the loss of the tooth from the alveolus. However, the success of its repositioning depends on the time elapsed from the moment of the trauma, and in some cases there are failures.

The crown, root, and the crown-root fractures are treated by conservative methods, but often the extraction of the compromised tooth is needed. In all cases, clinical and radiological monitoring is required to diagnose possible pulp complications or pathological root resorptions.

Regardless of the affected tooth or teeth, dental or dental-periodontal traumas can result in crown or crown-root destruction and even edentations, requiring a prosthetic treatment or an interdisciplinary approach.

3.1 PERIODONTAL DISEASE THAT LEADS TO LOSS OF PRIMARY AND PERMANENT TEETH

Early loss of primary or permanent teeth does not occur only because of dental caries, but sometimes occurs through the destruction of periodontal support in serious disorders which debut in primary or mixed dentition.

Although it is more characteristic to adulthood period, damage of the marginal periodontium was also found in

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children and adolescents. Thus, Bimstein et al. (1988) showed the abnormal presence of alveolar bone resorption associated with the presence of caries, in proportion of 7.6% for children aged 4 and 5.9% for children aged 5. Delaney et al. (1995) also signals the presence of manifestations such as periodontitis, recessions, gingival erythema and edema in pre-school children with neurotrophic systemic disorders.

Clinically, there are some differences between the characteristics of the gums and the periodontal tissue of the child in comparison with the adult tissue. These physiological differences should be taken into account when conducting a clinical examination. If, in the case of adult gum, the normal gum color is pink, the color considered normal is more reddish in children. After Ralph et al. (2011) the adult gingival edge has a "knife edge" aspect, while in the case of children, the gingival edge is much more rounded, an aspect that can be considered pathological in the adult. As for the consistency of adult gingival tissue, it is firm and resilient, while in children it is much softer due to the low density of connective tissue and lack of organization of collagen fibers. In terms of texture of the gingival surface, the appearance of "orange peel" present in adult is absent in children. As regards depth of survey and attachment level, if the physiological value of the gingival sulcus of 1-2 mm is kept constant for the adult throughout life (under physiological conditions), in children, the depth of the gingival sulcus evolves from greater depths corresponding to the time of replacement of the primary teeth with the permanent ones, to the physiological value of the adult, concomitant with the increase of the attachment area, which is initially more reduced than in the adult. All these differences

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are the expression of changes that take place until puberty.

Periodontal tissue, as their entire body, is found in constant changes in child development. Thus, these changes make it difficult to describe the normal aspects and differentiate them from the pathological ones (Benjamin et al., 1967).

Aggressive periodontitis that debuts in childhood or adolescence can be localized or generalized. Aggressive periodontitis can affect both primary dentition (therefore, in earlier classifications, these are recorded as "localized prepubertal periodontitis") and permanent dentition (formerly classified as "localized juvenile periodontitis").

According to Merchant et al. (2014), the clinical characteristics of aggressive periodontitis located in the two dentitions are similar: there are no consistently large deposits of tartar (reduced at early ages anyway), in the clinical exam the tissues do not appear to be excessively sore and the isolated bone defects are vertical or in a characteristic shape, arched or

"U" (Fig. 3.1.1-2), encompassing only one root, or more, with extension up to the apex, predominantly in the lower molars. In primary dentition, the disease is localized predominantly at the level of the molars, whereas in permanent dentition can occur only at the level of the molars, only at incisors or at the level of molars and also incisors.

According to Casamassimo et al. (2013), aggressive localized periodontitis (ALP) from primary dentition can progress into permanent dentition. It is assumed that ALP in primary dentition is due to an association of bacterial infection with specific, but minor immunological deficiencies.

Tetracyclines, commonly used for ALP therapy in permanent

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dentition, are contraindicated in primary dentition due to the risk of developing dental discoloration. Metronidazole is the drug of choice in ALP in primary dentition.

Fig. 3.1.1. The specific arcuate shape or “ U-shape" of isolated bone defect in tooth 3.6. in aggressive periodontitis, here affecting both roots in different

proportions (after Roshna & Nandakumar, 2012)

Fig. 3.1.2. Radiological aspect of localized aggressive periodontitis in primary dentition with alveolar bone damage around primary molars

(after Casamassimo et al., 2013).

According to the same author, aggressive localized periodontitis in permanent dentition is characterized by loss of alveolar bone predominantly around first permanent molars and permanent incisors. The loss of attachment is quick - at a rate of about 3 times higher than for a chronic condition.

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Localized aggressive periodontitis may evolve to a generalized aggressive periodontitis or may remain localized. There is an accumulation of bacterial plaque and slight signs of inflammation, but more pronounced than generally in adolescents (Fig. 3.1.3-5). Treatment is achieved by associating local therapeutic measures with systemic antibiotic therapy and microbiological monitoring.

Fig. 3.1.3. Clinical aspect of a 17-year-old patient with localized aggressive periodontitis, with the loss of the papilla in the incisor region and the appearance

of “black triangles" (case of Prof.Dr.Dr. Ştefan-Ioan Stratul)

Fig. 3.1.4. The Orthopanthomography of the patient from the previous figure, with evidence of bone defects in the first mandibular molars and permanent

central incisors (case of Prof. Dr.Dr. Stefan Stefan-Ioan Stratul)

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Fig. 3.1.5 Periodontal chart of the patient with localized aggressive periodontitis - from the periodontal chart the characteristic affecting of the area of the

permanent molars and incisors is revealed (case of Prof.Dr.Dr. Ştefan-Ioan Stratul)

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Generalized aggressive periodontitis (formerly known as the "rapid progressive periodontitis") can affect the whole dentition and does not self-diminish. There is an important accumulation of bacterial plaque and tartar, and the inflammation is severe. An aggressive therapeutic attitude is required with the association of local therapy with systemic antibiotic therapy. Generalized form affects all types of dentition, primary or permanent, being frequently associated with systemic diseases (Down's Syndrome, Papillon-Lefevre Syndrome), sometimes appearing as a buccal manifestation of serious general conditions such as neutropenia. (Fig. 3.1.6).

Fig. 3.1.6. Clinical and radiological aspect of a 7-year-old patient with congenital agranulocytosis, with massive tartar deposits, gingival ulceration areas and necrosis. Radiography of the patient reveals alveolar bone loss around primary

teeth that are clinically extremely mobile (after Baer & Benjamin, 1974).

Chronic periodontitis, although known to be adult- specific, may also occur in children and adolescents. Specialty literature is rather poor on this clinical entity, especially

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because the chronic periodontitis of children and adolescents has long been studied along with the aggressive form of periodontitis encountered in these age groups.

The Research, Science and Therapy Committee of the American Academy of Periodontology AAP emphasizes in a 2003 position paper that, as in the case of adults, also in pediatric patients chronic periodontitis can be localized or generalized, subdivision into the two forms respecting the same principles as for adults: localized form when less than 30% of the dento-periodontal units are affected by loss of attachment, or generalized when the damage is more than 30% of the teeth (Califano JV 2003). In both situations, the disease is characterized by a low rate of progression, but alternation with rapid destruction periods is not excluded. From the point of view of the extent of severity of the disease, there are three distinct forms: incipient (when attachment loss is up to 2 mm), medium (with attachment loss of 3-4 mm) and severe (when attachment loss is higher than 5 mm).

Although the prevalence of destructive periodontal disease is much lower in children and adolescents than in adults, however, children may develop various forms of periodontitis (Lӧe et al., 1991). Particularly, certain forms of periodontal disease encountered in young subjects are the expression of a known systemic disorder; in other situations, this systemic condition remains unknown. When the basic affection is family linked, it suggests a genetic predisposition for an aggressive form. Disease management is based on an anti-infectious therapy (non-surgical therapy), which may be accompanied by systemic antibiotherapy. Neither surgical therapy is excluded from the general therapeutic protocol.

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Independent of the periodontal disease form, the successful therapeutic principle based on early diagnosis of the disease remains valid, so it is recommended that the complete periodontal examination should be an integral part of pediatric routine pediatric visits (Novak et al., 1992).

Gingival manifestations of systemic diseases in children are also described, which can lead to the loss of primary and permanent teeth (Law, Silva, Duperon, Carranza 2015). Many of these diseases manifest themselves differently in children than adults (Albandar & Rams 2002). These include: ANUG (deeply underfed children under marked stress, under immunosuppressive treatment), endocrine disorders such as diabetes (both insulin-dependent, more commonly in children and also type 2), hormonal changes, haematological disorders such as leukemia (acute lymphocytic leukemia is today the major form of cancer in children aged under 7), leukocytosis (genetic - neutropenia, Chediak-Higashi and Papillon-Lefevre Syndrome, leukocyte adhesion deficiency syndrome, etc.).

As noted above, congenital diseases such as the Down’s Syndrome are associated with a high prevalence of severe aggressive periodontitis in early adulthood. According to Cichon et al. (1998) and Amano et al. (2000, 2001), the aggressive form of periodontal disease in young individuals with Down's Syndrome would be caused not by the reaction to a particular periopathogen but rather by a higher individual susceptibility leading to an immune inflammatory response.

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4. THE CONSEQUENCES OF EARLY LOSS OF PRIMARY TEETH

Early loss of primary teeth may be the cause of a pattern of dento-maxillary abnormalities that equally concern primary, mixed and permanent occlusion.

The loss of frontal teeth is relatively without consequences, while changes in the lateral area are significant, but also differentiated in relation to the tooth involved, namely the loss of the canine and the second primary molar is more severe than that of the first primary molar.

The main consequences of early tooth loss are:

modifying the eruption of permanent teeth (accelerating or delaying the eruption), changing the space for the permanent teeth eruption, and occlusal imbalance.

The eruption of permanent teeth that replace the early lost primary teeth can take two different ways:

a) Eruption can be accelerated, and the modification concerns mainly the premolars and almost never the canines.

The factor that causes the acceleration of eruption is the periapical osteitis process that simultaneously causes early loss of the primary predecessor. Thus, the eruption of the permanent tooth on the dental arch can also occur 4 years ahead of term and therefore with a high degree of root immaturity, with the following consequences: the post- eruptive development of such roots takes place very slowly, accompanied by limited apposition of alveolar bone and often complicated with occupying abnormal arch positions;

the eruption sequence may deviate from the normal formula,

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and the most disadvantageous alternative is the early eruption of the second premolars, which most frequently causes the loss of available space for teeth alignment.

b) Eruption may be more rarely delayed by the formation of a fibrous cap that blocks the vertical migration of the permanent tooth, a complication that occurs when the loss of the primary tooth appears very early.

The early loss of primary teeth is followed by the reduction of the remaining space, by sagittal movement of the adjacent teeth. (Fig. 4.1).

Fig. 4.1 The early loss of the left mandibular primary molars resulted in 3.6 bending mesially and the reduction of the space available for the eruption

of the premolars; Orthopantomography (Collection of the Department of Pediatric Dentistry)

Space loss, if not treated properly, may have immediate or long run consequences, preventing the eruption of the last successor teeth (superior canines or inferior second premolars).

In the maxilla, the canine does either not erupt, remaining included, or erupts to an ectopic position (Fig. 4.2).

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Fig. 4.2 Ectopic eruption of 1.3 and 2.3 in a patient with early loss of upper primary molars and a poor sagittal development of the maxilla

(Pediatric Discipline Collection)

Early loss of several primary molars in all hemi-arches leads to a complicated clinical entity called GMP = generalized mesial position (Fig. 4.3). By mesial migration of the permanent first molars, the space required for the eruption of the successors is reduced and serious dento-maxillary abnormalities with crowding and large space deficiency are installed. The orthodontic therapy in such cases involves the sacrifice of all the four premolars, which will have to be extracted in order to correct the space deficiency.

Occasionally, in parallel with the loss of space, the extrusion of the antagonists takes place, which in the primary occlusion is typically accompanied by the alveolar process.

This modification may result in blocking the sagittal movement of the teeth limiting the breach created by loss of the primary tooth and may have a favorable effect, especially on the position of the 6-year molars (Fig. 4.4).

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Fig. 4.3 Generalized mesial position with ectopic canines in all four quadrants and maintenance of neutral molar reports

Fig. 4.4 The vertical migration of 6.5 produced the occlusal blocking and prevented the mesial migration of 3.6

Occlusal imbalance is the most serious of the consequences of early tooth loss, disturbing the occlusal

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relationships and producing malocclusion, as a result of early eruption and dental movements around the early tooth loss outbreaks (Fig. 4.5). Thus, the early eruption determines the installation of occlusal immaturity outbreaks in disparty with the rest of the occlusal development, and the displacement of the limiting and antagonistic teeth creates interference and changes the dynamics of the bimaxillary relationships. From this point of view, the existence of unequal situations between the two arches or between the two hemi-arches of each jaw dictates the tightness and severity of the changes.

Fig. 4.5 Early loss of 7.4 and 7.5, with the mesioversion of 3.6 and 3.5 (intraosseous), preventing the eruption of 3.4 and the vertical migration of the

antagonists (Collection of the Department of Pediatric Dentistry)

The effects over time are difficult to predict because the changes may be primary or can be transferred into permanent occlusion, they may be minor in the primary occlusion stage and may worsen over time or, on the contrary, some serious aspects may improve or even disappear with time.

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5. SPACE MANAGEMENT IN PRIMARY DENTITION

Space management in primary dentition is extremely important because early loss of primary teeth can influence dental eruption, growth and optimal development of the stomatognathic system.

The key in controlling the space in primary dentition is to know what issues should be treated (Proffit WR et al., 2012).

Early loss of teeth at this age is approached by regions:

anterior (incisors and canines) and posterior (molars). The causes and treatment of early dental loss differ between the two regions (Casamassimo S.P. et al., 2013).

In the anterior area, the premature loss of incisors and primary canines is mainly due to dental trauma and dental caries. In the lateral area, premature loss of primary molars is mainly due to carious lesions.

Although the consequences of early tooth loss are revealed late, with the eruption of permanent teeth, space maintenance should be done as soon as possible after the loss of primary teeth in order to prevent space loss.

Early lost primary incisors are usually replaced for 4 reasons: space maintenance, functionality, phonation and aesthetics (Casamassimo S.P. et al., 2013).

Tooth loss in the anterior area is usually solved by applying removable devices (functional/myofunctional) provided with teeth or fixed appliances soldered at molar level, which replace the lost teeth from the anterior area (Fig. 5.1-3).

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Fig. 5.1 Clinical situation of a 4 year old child with trauma loss of the two central upper primary incisors (Collection of the Department of Pediatric Dentistry)

Fig. 5.2 Rehabilitation of the aesthetic function and phonation, by applying a palatal plate provided in the lateral area with anchoring elements (Collection of

the Department of Pediatric Dentistry)

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Fig. 5.3 Palatal plate provided in the anterior area with prosthetic teeth, saddle and artificial gums to restore the aesthetic function (Collection of the Department

of Pediatric Dentistry)

In the lateral area, we have to ensure the space maintenance resulting from the early loss of primary molars.

For this purpose, |5 space maintainers are generally used:

- the pediatric crown: maintains the mesiodistal dimension of endodontically treated primary teeth;

- band and loop space maintainer: ensures maintenance of the space resulted from the early loss of one or both primary molars (Fig.

5.4);

Fig. 5.4 Band and loop space maintainer fixed on a primary temporal molar (Collection of

the Department of Pediatric Dentistry)

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- the lingual arch: it is not recommended in the mandible due to the risk of interfering with the eruption of the permanent lower incisors. In the maxilla, in clinical situations when a unilateral loss of one primary molar occurs, a Goshgarian transpalatal arch can be applied and in situations with bilateral loss of first primary molars, a Nance device can be applied.

- the distal-shoe space maintainer: used in cases where there is an early loss of the second primary molar prior to the eruption of the first permanent molar. The device is sodered to the first primary molar and serves as a guide for the eruption of the first permanent molars in the correct position.

- removable partial dentures: useful when several primary teeth are lost and the remaining teeth cannot provide sufficient support for the application of devices (Fig. 5.5).

Fig. 5.5 Various degrees of coronal destruction of all primary teeth will require the application of an appliance as an activator (Collection of the Department of

Pediatric Dentistry)

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6. SPACE MANAGEMENT IN MIXED DETITION

Controlling or management of space in mixed dentition is essential and can prevent unwanted loss of arch length. It is the crossroad between paedodontics and orthodontics, where every mistake made by those who treat children leads to the development of dento-maxillary abnormalities that will later require complicated, long-lasting and expensive orthodontic therapy. It is the duty and liability of each dentist to evaluate each child patient not only from a restorative point of view, but from all aspects, keeping in mind that his therapeutic conduct can significantly influence the growth and normal development of the stomatognathic system.

In order to be able to issue a correct diagnosis and to make an optimal therapeutic decision, the dentist must know the elements to be assessed in order to achieve a favorable space management in the mixed dentition. These are: dental age, eruption sequence, time elapsed from tooth loss, delayed eruption of permanent teeth, bone overlying the dental bud, and available space.

Bratu E. et al., 2005, states that the space resulting from the early loss of a primary tooth closes within six months, so the space maintainer should be placed as soon as possible after extraction.

It is important to have an understanding of the patient's eruption sequence because sometimes disturbances in the normal eruption (eruption of the second permanent molar before the second premolar) can lead to a decrease in length of the dental arch.

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ISBN 978-606-786-144-0