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  • 1. UNIVERSITY OF GLASGOW Orthodontic management of hypodontia . Mohammed Almuzian 1/1/2013 .
  • 2. Mohammed Almuzian, 2013 1 Table of Contents Definition ............................................................................................................3 Classification.......................................................................................................3 Prevalence...........................................................................................................4 Aetiology.............................................................................................................6 Clinical presentation ...........................................................................................7 Features ..............................................................................................................8 Management........................................................................................................9 Multidisciplinary team .......................................................................................9 Indications for Treatment....................................................................................9 Factors to be considered in the management of hypodontia...............................9 Sequence of treatment.......................................................................................10 Treatment options .............................................................................................11 Space opening & space maintenance................................................................13 Advantages........................................................................................................13 Disadvantage.....................................................................................................13 Mechanics .........................................................................................................13 Space closing or partial space closure to reduce extent of prostheses..............14 Indication ..........................................................................................................14 Advantages........................................................................................................15 Disadvantages ...................................................................................................15 Mechanics .........................................................................................................16 Orthodontic appliances used in hypodontia cases ............................................17 Difficulties in orthodontic mechanotherapy of hypodontia..............................18
  • 3. Mohammed Almuzian, 2013 2 Retention regimes .............................................................................................18 Restorative options for space replacement .......................................................19 Temporary in-treatment replacement................................................................19 Long term replacement .....................................................................................20 Techniques to increase the amount of bone at area of hypodontia for implant insertion.............................................................................................................26 Advantages and disadvantages of build-up small teeth before, during or after orthodontic treatment........................................................................................27 Factors affect the choice of the prosthesis to restore the space........................28 Treatment option for missing lower premolars ................................................29
  • 4. Mohammed Almuzian, 2013 3 Orthodontic management of hypodontia Key articles (Carter et al., 2003; Savarrio & McIntyre, 2005, Kokich 1997) Definition 1. The term hypodontia is generally used to describe developmental tooth absence excluding the third molars (Goodman et al., 1994). Hypodontia may be sub-classified according to its severity, as mild (1–2 missing teeth) almost 80%, moderate (3–5 missing teeth almost 10%) or severe (≥6 missing teeth almost 1%). (Larmour 2005, Naini et al., 2011) Classification A. According to the number of teeth involved (Goodman et al., 1994). 1.Hypodontia refers to a lack of 1-6 teeth, excluding third molars 2.Oligodontia (sever hypodontia) refers to a lack of more than six teeth, excluding third molars Hobkirk et al., 1995 3.Anodontia refers to a complete absence of teeth in one or both dentitions. Very rare B. According to the inheritance pattern (Wright et al., 1993). 1. Non-syndromic hypodontia A. Nonsyndromic hypodontia can be subclassified according to method of occurrences (Burzynski and Escobar, 1983):  Familial or Inherited. This form can follow autosomal dominant, autosomal recessive or autosomal sex-linked patterns of inheritance, with considerable variation in both penetrance and expressivity.  Sporadically 33% of hypodontia cases B. Non-syndromic hypodontia can be sub-classified according to teeth involved and their number:
  • 5. Mohammed Almuzian, 2013 4 1.Localized incisor–premolar hypodontia (OMIM 106600), which affects only one or a few of these teeth. This is the most common form and is seen in around 8% of Caucasians (Nieminen et al, 1995). 2.Oligodontia (OMIM 604625) occurs in around 0.25% of Caucasians and can involve all classes of teeth (Sarnas & Rune, 1983). C. Candidate genes for nonsyndromic human hypodontia (Vastardis et al., 1996; Lammi et al., 2004; Suda et al., 201, Cobourne, 2007, Han et al., 2008):  MSX1 associated with premolar and lateral incisors. Usually associated with sever hypodontia.  EDA gene mutations usually includes the loss of mandibular and/or maxillary incisors and canines  PAX9. Associated with molars.  AXIN2 which is mainly associated with Finnish family hypodontia. 2. Syndromic hypodontia  Seen in association with Down syndrome, ectodermal dysplasia, CCDS, CLP & CP , Van de Wound syndrome, Rieger and Book syndrome. Larmour 2005, Shapira et al., 2000), (Kerwetzki and Homever, 1974; Marković, 1982b; Parsche et al., 1990), (Uthoff, 1989).  Candidate genes MSX1 (MSX1 represents a candidate gene for both syndromic and nonsydromic hypodontia). Prevalence Wide range of prevalence because of the geographic and ethical variation 1. Dentition: A. Deciduous teeth 0.1 – 0.9 % (1-9 in 1000) with the maxillary then mandibular lateral incisors being most commonly missing. As a rule, when the primary tooth is missing, its permanent counterpart will also be absent (Hall, 1983).
  • 6. Mohammed Almuzian, 2013 5 B. In permanent dentition, 4-6% excluding 8s (Grahnen, 1956). Polder 2004 4.6% male and 6.4% in female  (Localized incisor–premolar hypodontia around 8% of Caucasians (Nieminen et al, 1995)  Oligodontia occurs in around 0.25% of Caucasians (Sarnas & Rune, 1983). 2. Ethnic variation • Ethnic variation exists, (Endo et al, 2006a; Buenviaje and Rapp, 1984; Zhu et al, 1996; Polder et al, 2004). • The incidence of missing permanent teeth, excluding the third molar, is 3.4 per cent in Swiss children, 4.4 per cent in American children, 4.6 per cent in Israeli children, 6.1 per cent in Swedish children, 8 per cent in Finnish children, and 9.6 per cent in Austrian children (Thilander and Myrberg, 1973; Brook, 1974; Aasheim and Ögaard, 1993; Slavkin, 1999). • The common missing tooth types in Caucasians being lower second premolars > upper lateral incisors > upper second premolars > lower central incisors Larmour 2005. • In some Asian populations, lower central incisors are reported to be commonly missing. 3. Gender • F:M = 3:2 (Larmour, 2005, (RØLling, 1980) 4. Teeth series • As a general rule, if only one or a few teeth are missing, the absent tooth will be the most distal tooth of any given type (Jorgenson, 1980; Schalk van der Weide et al., 1994). 5. Location: • Lower > upper (RØLling, 1980) • Left > right Wisth et al., 1974 (RØLling, 1980) but other show the opposite (Fekonja, 2005) 6. Teeth affected:
  • 7. Mohammed Almuzian, 2013 6 • 25-35% of all third molars • Lower premolars most commonly absent and mainly symmetrical (2.6%) (RØLling, 1980). • Missing laterals: 2% More bilaterally than unilaterally. Familial tendency associated with peg contralateral laterals incisors and palatally impacted canines. It represents 20% of the hypodontia cases (Bren et al). • Lower incisor 0.2% of Caucasians but more common in Asian. • U3s developmentally absent 3's: 0.08% (Bren et al) • First and second molars, is rare (Simons et al, 1993). • The overall prevalence of peg-shaped maxillary permanent lateral incisors was 1.8%. he prevalence rates were higher among Mongoloid people, orthodontic patients, and women. Although the prevalence of unilateral and bilateral lateral incisors was the same, the left side was twice as common as the right side. Subjects with unilateral peg-shaped maxillary permanent lateral incisors might have a 55% chance of having lateral incisor hypodontia on the contralateral side.Hue et al meta-analysis 2013. Aetiology of Hypodontia A. Genetic 1. Familial hypodontia: (Brook , 2002) Hypodontia prevalence was higher in first-degree relatives (22%) of hypodontia index cases than in the general population (4.4%), there is a threshold in hypodontia so that: Below threshold  microdont teeth Above threshold  missing tooth 2. Genetic regression: over evolution from mammalian dentition to primate dentition, we lost teeth ie dogs have 3 incisors in each quadrant; we as human have 2 incisors only. B. Environmental (Graber, 1978)
  • 8. Mohammed Almuzian, 2013 7 I. Systemic disruption of Dental Lamina: eg. Ectodermal dysplasia  disturbance of all the tissue developing from the outer layer (ectoderm) of the foetus due  chemo  radiotherapy  infection  low birth weight  drugs  hormonal II. Localised disruption of Dental Lamina: eg. Cleft of alveolus results in transection of the dental lamina. III. Nutritional Deprivation: environmental regression  if you don’t feed properly (Ca), teeth will suffer. But in Africa there is starvation yet the frequency of missing teeth is less than that seen in the Western population. Other enviromenal causes are infection, radiation. Larmour 2005 C. Polygenetic inheritance (Suarez and Spence 1974) Clinical presentation or sign of hypodontia (Dhanrajani, 2002) 1. Delayed eruption. 2. Asymmetrical eruption 3. Bazar tooth form (Brook 1984) 4. Infraocclusion 5. Retained primaries 6. Absent primaries 7. Lack of alveolar bone growth
  • 9. Mohammed Almuzian, 2013 8 Features of hypodontia cases (Larmour, 2005, Cobourne, 2007) A. Skeletal feature (depending on the severity of hypodontia) 1. Retrognathic and hypoplastic maxilla. Wisth 1974 2. Small MMPA and reduced vertical dimensions. Woodworth 1985 B. Alveolar features 1. Lack of alveolar bone (Guckes, 2002) 2. There is often a fairly flat palatal vault which results in reduced anchorage capacity of upper removable appliances, Nance palatal crib or implant placement. C. Occlusal features (Fekonja, 2005 #410) 1. Upright incisors 2. Increased overbite. D. Dental features 1.Delayed and asymmetric eruption of permanent teeth. The second premolars are particularly prone to delays in dental development and may not be visible radiographically until the age of 9 years. Hence, a diagnosis of their absence should be made with caution before this age. Wisth et al., 1974 2.Prolonged retention of primary teeth (Kurol, 1984)(Nunn, 2003) 3.Infra-occlusion of primary teeth (Kurol, 1984) 4.Ectopic eruption or impaction of the adjacent teeth particularly maxillary canines. Up to 5% of those with absent lateral incisors may be complicated by maxillary canine impaction. (Brin 1986) 5.Adjacent teeth  Microdontia (Brook 1984)  Conical crown. Brook 1984  Transposition Peck 1993  Enamel hypoplasia. Brook 1984  Molar taurodontism: This is a developmental anomaly where the roots of the molars are shortened with elongated pulp chamber. The roots of taurodont
  • 10. Mohammed Almuzian, 2013 9 teeth may be more prone to orthodontically related root resorption and they offer less anchorage because of their reduced surface area. Additionally, endodontic treatment and extractions may be complicated by the abnormal root morphology. Seow 1989 Management of hypodontia Multidisciplinary team for hypodontia treatment (Larmour, 2005) 1. Clinical nurse coordinator 2. Orthodontist 3. Restorative dentist 4. Paediatric and prosthodontics dentist 5. Oral surgeon 6. General dental practitioner 7. Geneticist Indications for Treatment (Shaw 1980, 1981) 1. Aesthetics 2. Functional 3. Dental rehabilitation 4. Dental health problems  Food impaction due to tipped or drifted teeth  Traumatic OB  Infraoccluded primary teeth Factors to be considered in the management of hypodontia (Carter & Gillgrass, 2003 (Dhanrajani, 2002)
  • 11. Mohammed Almuzian, 2013 10 1. Age: Younger preferred because OB can be corrected and stability better, also PD problem and caries become an issue in adult 2. Severity As the number of absent teeth increases the treatment option of space closure becomes unrealistic. 3. Facial profile 4. Intra-arch relationship (crowding or spacing) 5. Inter-arch relationship (dynamic and static relationship) 6. Shape, size and colour of the adjacent teeth 7. Smile and gingival line 8. Clinical situation of the primary and permanent teeth 9. Patient's opinion and co-operation 10.Clinician philosophy Sequence of treatment Kokich and Spear, 1997 1. Orthodontists and restorative dentists establish realistic objectives rather than idealistic 2. Create a diagnostic set-up and Kesling set up (the two are different from each other) 3. Determine the sequence of orthodontic treatment 4. Build-up malformed teeth,  Where should the maxillary lateral incisor be positioned mesiodistally relative to the central incisor and canine? Should be more space bet 2 and 3  Where should the lateral incisor be positioned buccolingually: toward the labial, in the center of the ridge, or toward the lingual? Depend on the type and thickness of final restoration  Where should the lateral incisor be positioned incisogingivally? This relationship is determined by the position of the gingival margins
  • 12. Mohammed Almuzian, 2013 11 5. Evaluate gingival esthetic 6. Provision space to facilitate restorative treatment 7. Take progress radiographs, and measure the space with Strowman T ruler. 8. Sometimes silcon trays to evaluate the space 9. Occlusal adjustment 10. Interact during finishing Treatment options A. Treatment for hypodontia in primary dentition No treatment is indicated at this stage. However removable dentures for psychological and functional reasons might be used but it will require regular adjustments during growth. Retention and stability may be problematic in those with poorly developed alveolar ridges.(Fekonja, 2005)(Tarjan, 2005) B. Mixed dentition 1.Involve mainly the interceptive treatment Extract 1o tooth early  allow space closure. Some recommend extracting primary tooth, allowing permanent teeth to erupt and close space, then reopen space at adulthood, so by this way we preserve the bone. Lindqvist, 1980 Other IO treatment involve: I. RFM when class III problem is present.(Kircelli, 2006) II. Guided eruption III. Diastema closure IV. Space management. V. Serial extraction VI. IO for impacted canine.
  • 13. Mohammed Almuzian, 2013 12 VII. Composite build-ups to improve aesthetics of microdont permanent teeth or worn deciduous teeth 2.Retain primary tooth:  As long as possible & replace with prosthesis after cession of the growth, this will help in preserving alveolar bone  Permanently, retain the primary tooth (if the Es survive until 20yrs then they appear to have a good prognosis for long term survival Bjerklin & Bennett,2000) C. Treatment for hypodontia in permanent dentition. Hobkirk et al., 1995 1. Accept 2. Restorative treatment without orthodontic either by implant, bridge, transplantation, teeth build-up or by retaining primary teeth with alteration in the shape or size by build-up, premolarization or hemisection and slicing. 3. Combined planning, orthodontics/restorative opinions necessary and sometime surgery might be involved in severe cases. This involve the following options: Missing Class I Class II Class III 2 If closing space  xtn E to allow mesial drift of buccal segments Space can be used as part of treatment Space should be preserved and regained to allow proclination lower 5 Xtn LE early (9yrs) to allow mesial drift Keep LE as long as possible  lower arch should be as big as possible May be used as part of xnt to treat malocclusion
  • 14. Mohammed Almuzian, 2013 13 A. Space opening or space maintenance Advantages space opening (Tarjan, 2005) 1. Improved aesthetics specially if the adjacent of poor shape and colour 2. Improved function 3. Space closure may be slower than normal and may not be possible to close the space completely. Asher & Lewis, 1986 Disadvantage space opening Commits the patient to a permanent prosthesis Mechanics 1. Before treatment combine treatment planning with trial wax set ups 2. The amount of space required is determined according to:  Standard tooth size  Golden proportion  Contra-lateral sizes  Bolton analysis (this only applied if we have one tooth type missing)  Restorative opinion according to the future restorative prosthesis. 3. Fixed appliances — for 3dimensional tooth control 4. 'Push-pull' mechanics — eg. involving open coil spring in the 2 region (the 'push') and lacebacks to retract the canine (the 'pull') 5. Use tipedge braket or wire bending or bracket positioning to correct root parallisim 6. Once appropriate space has been opened, closed-coil spring or an acrylic denture tooth attached to the orthodontic archwire via a bonded bracket should be placed: To maintain space To restore aesthetic.
  • 15. Mohammed Almuzian, 2013 14 7. In case of missing E, premolarization of the E is recommended to mimic the 5s, but only if the root configuration and morphology of the E allowed that without compromising the pulpal health. 8. Retention — VFRs (can prevent relapse in all 3 dimensions) or Hawley- type retainer incorporating prosthetic teeth and wire stops mesial and distal to the acrylic tooth. Space closing and canine substitution Indication (Kinzer & Kokich 2005) 1. Macro aesthetic factors:  Profile: After one of the two occlusal criteria has been satisfied, the profile should be evaluated. Generally, a balanced, relatively straight profile is ideal. However, a mildly convex profile also may be acceptable A patient with a moderately convex profile, retrusive mandible, and a deficient chin prominence may not be an appropriate candidate for canine substitution.  Type of malocclusion (crowding and incisor relationship): There are two types of malocclusions that permit canine substitution. The first is an Angle class II malocclusion with no crowding in the mandibular arch. The second alternative is an Angle class I malocclusion with sufficient crowding to necessitate mandibular extractions.in class III condition opening the space for lateral incisors will cause wagon wheel effect and make the placement of the implant more difficult. 2. Mini aesthetic factors: Canine shape and color: The ideal lateral incisor substitute is a canine that is the same color as the central incisor, is narrow at the CEJ buccolingually and mesiodistally, and has a relatively flat labial surface and narrow mid-crown width buccolingually.
  • 16. Mohammed Almuzian, 2013 15 3. Micro aesthetic factors: Gingival and lip level: If the patient has an excessive gingiva-to-lip distance on smiling, the gingival levels will be more visible. Also, in patients with high smile lines, a prominent canine root eminence could also be an esthetic concern Advantages 1. No prosthetic replacement (Tuverson 1970) 2. Better stability (Tuverson 1970, Robertsson, 2000) 3. Better periodontal health in the long term if 3 replaces 2 rather than using prostheses and no TMD problems. (Robertsson & Mohlin, 2000, Robertsson, 2000, Senty 1976) 4. Better aesthetic. Rosa et al (1998) and Robertsson, 2000 suggest ways in which the orthodontist in combination with the restorative dentist can make space closure a more attractive alternative. 5. Excellent acceptance by patients. Turpin 2004 showed that space closure has better outcome in TMJ, and PD health and patient satisfaction. Disadvantages 1. Facial aesthetic: incisors might be retracted and affect the facial profile by flattening it. Sergl and Stodt 1970 2. Dental aesthetic:  ML shift in unilateral hypodontia (Robertsson, 2000)  Un-aesthetic canine replacing lateral regarding colour, size and shape. Zachirsson and Thilander 1985  Unsightly gingival architecture, which tends to worsen with age. Zachirsson and Thilander 1985  Constriction of the dental arch and dark buccal corridor. Angle 1907  Bolton discrepancy. Therefore, a critical step in the patient-selection process is the completion of a diagnostic wax-up. This enables the orthodontist and
  • 17. Mohammed Almuzian, 2013 16 dentist to evaluate the final occlusion, measure how much canine reduction is necessary, and determine if an aesthetic final result is achievable. Bolton 1967 3. Functionally: loss of canine guidance and TMD. Thomas 1967, (Robertsson, 2000) 4. Mechanically: space difficult to close. (Cameron, 1996) 5. Retention: prolonged retention required. (Carter, 2003) Mechanics 1. Before treatment  Combine treatment planning with trial wax set ups. Asher & Lewis, 1986  Sometime in unilateral missing of incisors, the contralateral might be extracted for symmetrical purposes 2. Set up stage  Invert 3 bracket or bond 2 bracket to the 3 — will torque the 3 root palatally, reducing the 3 eminence and locate the 3 root similar to the position that should have been occupied by the 2. Rosa & Zachrisson, 2001  Bond 3 bracket on the 4 tooth with (Shroff et al., 1996) A. More distal position to get mesio-labial rotation of the 4 (good aesthetics because the palatal cusp will be hidden and the 4 will appear wider mesiodistally) and in order to allow the 4 to use more space MD and also help in avoiding premature contact with lower during function. B. More occlusal position to get intrusion of the 4 and then build it up, this might help in reducing the palatal cusp interference with the lower canine and move the gingival line of the 4 more apically to simulate the 3s.  3 extrusion to allow the gingival margin to be positioned more incisally to mimic that of the 2 with gradual selective grinding (apply Durphat after each cession of grinding). As they erupt, a thicker portion of the crown comes into contact with the mandibular incisors. This often causes prematurities that must
  • 18. Mohammed Almuzian, 2013 17 be equilibrated periodically during the alignment stage of orthodontic treatment. Thordarson et al.,1991 3. Anchorage wise  Use reverse pull HG or TAD if necessary to close spaces in a mesial direction. Yanosky & Holmes,2008  The space might be used as a way to correct the malocclusion like crowding or increased OB. Goodman et al., 1994 4. Finishing  Selective grinding of the 3 tips  Selective grinding of 3 cingulum to avoid interferences  Bleaching of the dark 3s.  Build up the buccal cusp of the intruded 4s.  The problem of reshaping by selective grinding might expose more dentine causing sensitivity and darkness of the tooth. 5.Retention Bonded wire retainer+VFR or removable appliance. Goodman et al., 1994 Orthodontic appliances used in hypodontia cases 1. Removable appliances are very useful in the management of hypodontia cases for the following purposes: • For overbite reduction, • Tipping movements • For space maintenance in the upper arch (Retainers). 2. Fixed appliances are otherwise almost always the appliance of choice as they allow greater control of tooth movement . 3. Orthodontic-surgical approach 4. Combination
  • 19. Mohammed Almuzian, 2013 18 Difficulties and challenges in orthodontic mechanotherapy of hypodontia 1. OH: Patients with hypodontia, with their tendency to microdontia, may be more at risk of plaque accumulation between bracket and gingiva caused by their close proximity, and may need specific oral hygiene advice and preventive measures to avoid these undesirable consequences. 2. Bracket bonding and fitness: due to altered tooth morphology, with altered enamel structure and microdontia. 3. Long spans of unsupported arch wire 4. Anchorage consideration 5. Aligning stage: Up righting and aligning teeth specially rotated teeth 6. Levelling stage: Overbite reduction in the absence of a stable occlusal stop. (by URA, functional appliance or Dalh appliance, intrusion mechanics in adult or in high MMPA or orthognathic surgery) 7. Space closure stage: Space closure in the absence of crowding is difficult 8. Root resorption: Patients with moderate to severe hypodontia have also been shown to be more susceptible to apical root resorption. This is due to:  Unusual root morphology  Long treatment  Extensive tooth movements required  Microdontia that result in short inter-bracket span and heavier forces.  Genetic correlation. 9. Retention and stability. Due to certain unstable movement Retention regimes for hypodontia 1. Long term part-time wear of a removable retainer, a removable retainer is fitted which carries acrylic teeth and wire stops. The retainer can also conveniently include a flat anterior bite plane to encourage further
  • 20. Mohammed Almuzian, 2013 19 overbite reduction and increase the inter-occlusal space to facilitate the provision of the definitive restoration 2. Bonded retainer after all diastema ac closure. 3. Adhesive bridge like a cast metal Maryland design can be considered supplied with VFR for 6 months followed by night time wear for at least a further 6 months. Survival rate is 80% over 6 years. 4. Adjunctive procedure: • IPS • CSF • Over correction of the rotation • If a rotated tooth is to be used as an abutment, either a second abutment must be included in the bridge to prevent rotational relapse or include multiple teeth as bridge abutments to prevent the undesirable drifting and relapse that may occur if a single cantilevered pontic is used. Restorative options for space replacement Temporary in-treatment replacement 1) Prosthetic tooth and labial bracket 2) Prosthetic tooth and acrylic flange cantilever 3) Prosthetic tooth attached directly to the archwire: indicated when the underlying tooth is impacted and the plan is extrude it while the acrylic tooth in place. A step in the AW can be made to provide more accessibility. The aim is to avoid the bracket thickness. 4) Extracted tooth: When extraction of a tooth is enforced, and the coronal tissue remains intact and not discoloured, use of the tooth itself can be an ideal choice of in-treatment replacement
  • 21. Mohammed Almuzian, 2013 20 Long term replacement 1) Removable Prostheses 2) Fixed Prostheses 3) Implant 4) Autotransplantation In details 1.Removable Prostheses  Acrylic  Co/Cr  Overdentures in patient with microdontia.  VFR with tooth + composite droplet same like invislaign to control the bodily position of the tooth. Better to give the pt two retainer one with tooth during the day the other at night without tooth to allow healing of the gum. Indications and advantages 1. Poor OH and high caries rate. 2. Medical contraindication for fixed options 3. Children who still growing; 4. Temporary solution 5. When adjacent teeth not suitable for fixed prosthesis 6. Insufficient bone for Implants; 7. Numerous teeth missing. Advantages 1. Simple to construct.
  • 22. Mohammed Almuzian, 2013 21 2. No preparation of natural teeth. 3. Appearance of prosthetic teeth can be extremely natural. 4. Can restore missing/deficient hard and soft tissue as well as missing teeth. 5. Can act as retainers. Disadvantages 1. Bulk 2. Gradual wear of prosthetic teeth 3. Gradual alteration in supporting tissues 4. Psychological opposition to removable prosthesis 2.Adhesive Fixed Advantages 1. Fixed restoration (could be metal fused to ceramic or full porcelain) 2. Could be cantilever or fixed fixed RBB. 3. Used in any age 4. Relatively simple to construct 5. Preparation of natural teeth required is relatively conservative, confined to enamel only 6. Potential for temporary retention of post-orthodontic tooth position. If the plan to use the bridge as a temporary measure until implant becomes sensible, then RBB without preparation is indicated as a reversible method and the patient should be warned about a potential need for alveolar grafting before implant. However, because of continued facial growth and compensatory tooth eruption, several years can elapse between completion of orthodontic treatment for a teenage patient and implant placement. There are reports by Olsen & Kokich in 2010 that, after successful orthodontic opening of the implant space,
  • 23. Mohammed Almuzian, 2013 22 the central incisor and canine roots reapproximate in 11% of cases during retention and prevent implant placement. To ensure sufficient space for implant placement, Olsen & Kokich in 2010 recommended at least 6.3 mm of intercoronal space and 5.7 mm of interradicular space between the adjacent central incisor and canine. A bonded wire or resin-bonded bridge will help to reduce root approximation that might occur during retention, some prefer to put implant if the pt is 18+ while he or she in the active orthodontic treatment 7. Hussey 1996 show that 88% remained bonded over 3 years using cantilever RBB. 8. Garnett 2006 showed that success rate almost good (80%) over 59 months. 9. Heather 2009 (systematic view) suggests that RBBs have an 87.7 percent five-year survival rate—are a treatment alternative to conventional bridges and implant-supported crowns. 10. Pjetursson 2007 estimated these alternatives to have a 87.7% over 5 years. 11. Garrett 2007 showed that Bristol bridge has good success rate. Disadvantages 1. Potential for debond 2. Potential instability of teeth if prosthesis is also being used for retention 3. Difficult to cope with spaced teeth 4. Potential for caries 5. May complicate oral hygiene measures 6. Visible metal retainers 'grey-out' from metal backing NB: Cantilever bridge has a better success. This can be explained by the fact that the teeth with an intact periodontal ligament (i.e. not ankylosed) have an inherent mobility. So, each tooth will move in and out of the socket and in a
  • 24. Mohammed Almuzian, 2013 23 vertical direction under masticatory load. The amount of mobility and overall direction of movement depends on the size of the root and amount of periodontal ligament (support and width), and the position of the tooth in the arch. If the teeth are joined together via a restoration (a bridge, a splint), they still retain their own underlying mobility, and it is this which can be responsible for teeth becoming debonded from restorations. This factor has to be taken into consideration when designing fixed restorations which are meant to retain teeth in position, since any failure can be followed by unwanted tooth movement.) The addition of rest to hold the other adjacent tooth to help in retention is advisable. 3.Fixed-Fixed Prostheses Indications and advantages  No paralisim of roots  Edentulous span is short;  No enough bone for implant  Medical contraindication  Financial issue Advantages  Fixed  Possible to make minor changes in relative sizes and alignment of abutment/pontic teeth  Potential for retention of post-orthodontic tooth position, Disadvantages  Cost
  • 25. Mohammed Almuzian, 2013 24  Preparation of abutment teeth. Literature varies but may be up to 10% loss of vitality of abutments previously presumed vital 10 years after preparation (Karlsson, 1986)  May complicate oral hygiene  Difficult to cope with spaced teeth  Failure rate 4. Implant Implant treatment is normally deferred until the jaws have stopped growing, to avoid related problems, typically in the very late teens or early 20s (Nordquist and McNeill, 1975; Ödman et al., 1988; Oesterle et al., 1993; Robertsson and Mohlin, 2000; Rosa and Zachrisson, 2001). The orthodontics can be useful facility with implant service by: 1) Controlling the space for implant (open and reduce the space). Research suggests a minimum of 1mm between implant and natural tooth to allow adequate healing and adequate papilla development. With the standard width of an implant platform being 4mm, this means at least 6mm must be created to ensure adequate room for placement. 2) Change root angulation 3) Prepare the peri-implant site by developing a new bone (if the alveolus is narrow or the sinus is low) Indications and advantages  Good Aesthetics  Diastema can be produced (not connected to adjacent teeth).  Enables use of overdenture prosthesis.  Can be used during orthodontic treatment for anchorage
  • 26. Mohammed Almuzian, 2013 25  Long-term survival however is good Lindhe et al 1998 in his meta-analysis suggesting greater than 90%. Tan et al in 2004 showed 89%.Pjetursson et al in 2012 showed it is 89% The classification of implants may be based on:  Position of placement (subperiosteal, transosseous, endosseous)  Material of construction (titanium, ceramic, carbon, alloys)  Design (screw, cylinder) 5.Autotransplantation  Success rates can be over 90% if transplanted into extraction socket  As low as 60% in artificially-formed sockets ( when tooth fully- developed)
  • 27. Mohammed Almuzian, 2013 26 Techniques to increase the amount of bone at area of hypodontia for implant insertion 1) Autogenous bone graft From oral sites  Symphysis, Retromlar area, Maxillary tuberosity, Zygoma Other areas for harvesting
  • 28. Mohammed Almuzian, 2013 27 Iliac crest Tibia; 2) Allogenic bone graft: theoretical concern over possibility of disease transmission using substitutes. 3) Osteodistraction and crestal widening. Advantages and disadvantages of build-up small teeth before, during or after orthodontic treatment (Kokich and Spear, 1997) 1. Before Orthodontics Advantages • Restoration acts as a space maintainer during treatment Disadvantages • Space may not be available before treatment for a build-up • Altering the crown morphogy may result in incorrect bracket placement • The restoration at risk of damage during bracket removal at completion of the orthodontic treatment. 2. During Orthodontics Advantages • Excess space can be created temporarily to aid mesial and distal restorative • Restoration acts as a space maintainer Disadvantages • Gingival inflammation can jeopardize bonding and ideal finishing. • If composite is added to the labial surface of the tooth it may be necessary to drop down archwire out tooth position. 3. After Orthodontics Advantages • Allows gingival inflammation to subside after appliance removal.
  • 29. Mohammed Almuzian, 2013 28 Disadvantages • A new retainer may need to be after completion of restorative treatment • More difficult to finish interproximally correctly. Factors affect the choice of the prosthesis to restore the space (Kokich and Spear, 1997) 1. Smile line 2. Gingival thickness 3. Height and width of bone at hypodontia site 4. Bone quality, volume and anatomy 5. Root position of the teeth adjacent to the implant site 6. Width, height and form of the adjacent teeth 7. Interocclusal space 8. Presence of parafunctional activity and occlusal forces 9. pt motivation; 10. social factors; 11. medical factors 12. no. teeth to be replaced; 13. patient and clinician preferences
  • 30. Mohammed Almuzian, 2013 29 Treatment option for missing lower premolars
  • 31. Mohammed Almuzian, 2013 30