Vertical alveolar growth in subjects with infraoccluded mandibular deciduous molars.

INTRODUCTION: Our objective was to compare vertical alveolar growth in areas adjacent to infraoccluded deciduous molars with growth in areas of deciduous molars and normal occlusion for a period of at least 1 year by using digital subtraction radiography. METHODS: This case-control study included 40 pairs of panoramic radiographs of growing patients with infraoccluded deciduous molars and 40 pairs of radiographs of patients without infraoccluded deciduous molars. One radiograph at baseline was obtained at diagnosis, and the other at least 1 year later. The subjects and the controls were matched according to chronologic age and time interval between the 2 radiographs. The 2 groups were compared with regard to vertical alveolar growth and vertical tooth movement. Measurements were assessed by using nonparametric tests (Mann-Whitney and Friedman) and a multiple comparison test. Significance was set at 5%. RESULTS: A statistically significant difference was observed between the groups with regard to vertical alveolar growth measured on the bone crest between the first permanent molars and second premolars. CONCLUSIONS: Vertical alveolar growth between the first permanent molar and the second premolar adjacent to the infraoccluded teeth was smaller than in areas adjacent to teeth with normal occlusion.

Primary mandibular distraction for management of nocturnal desaturations secondary to temporomandibular joint (TMJ) ankylosis.

OBJECTIVES: Mandibular advancement is a proven method in the management of obstructive sleep apnoea syndrome (OSAS) which may manifest as sleep disturbances with nocturnal desaturations during sleep (NDS). The purpose of this study is to evaluate the role of primary osteo-distraction prior to ankylosis release in pediatric patients, diagnosed with NDS secondary to temporomandibular joint (TMJ) ankylosis. METHODS: Three patients in the age group of 8-12 years diagnosed with OSAS secondary to TMJ ankylosis underwent primary osteo-distraction for mandibular advancement. They were evaluated pre- and post-operatively using radiographs, over night pulse oximetry, and subjective evaluation of their sleep patterns. RESULTS: All the three patients showed significant improvement in their saturation levels with a mean oxygen saturation of 94.66%. There was marked reduction in their snoring and sleep/awakening patterns. The mean advancement of the mandible in the three patients was 13.8mm. CONCLUSION: Primary mandibular distraction is an effective method of correction of nocturnal desaturations during sleep in patients with TMJ ankylosis.

Influence of Dentoalveolar Ankylosis on the Biomechanical Response of a Single-rooted Tooth and Surrounding Alveolar Bone: A 3-dimensional Finite Element Analysis.

INTRODUCTION: Dentoalveolar ankylosis necessarily accompanies the loss of periodontal ligament (PDL), which might alter the biomechanical response of the tooth. The purpose of this study was to investigate the influence of dentoalveolar ankylosis on a single-rooted tooth and the surrounding alveolar bone structures in the biomechanical standpoint. METHODS: A basic model of an intact maxillary central incisor and the surrounding bone structures was chosen for the numeric analysis. From this basic model, 6 different models were further developed by combining 3 types of endodontic status (an intact model, a nonsurgically treated model, and a surgically treated model) and 2 types of periodontal attachment condition (models with or without PDL). For each condition, maximum von Mises stress (σ max) in dentin and bone and maximum tooth displacement (ΔR max) were calculated. RESULTS: In models with dentoalveolar ankylosis, stress was concentrated on the cervical dentin around the cementoenamel junction and the alveolar bone crest, whereas the stress was more evenly distributed along the entire length of the root in models with normal PDL. The models with dentoalveolar ankylosis showed higher stress values in dentin (44.72%-80.56% of σ max increase) and bone (24.23%-80.68% of σ max increase) and lower tooth displacement (59.22%-63.97% of ΔR max decrease) compared with the models with normal PDL. CONCLUSIONS: Dentoalveolar ankylosis exerts significant changes on the biomechanical response of a single-rooted tooth and the surrounding bone structures. The dentoalveolar complex with ankylosis showed characteristic stress concentrations, increased stress values, and decreased tooth displacement compared with that with normal PDL.

An interview with Sylvia Frazier-Bowers.

Dr. Frazier-Bowers is an associate professor at the University of North Carolina, Chapel Hill (UNC-CH), in the Department of Orthodontics. She received a BA from the University of Illinois, Urbana-Champaign, and a DDS from the University of Illinois, Chicago. After completing the NIH Dentist-Scientist Program at UNC-CH in Orthodontics (Certificate, 97') and Genetics and Molecular Biology (PhD, 99'), she completed a post-doctoral fellowship at the University of Texas Health Science Center, Houston (UTHSC), in the Department of Orthodontics. Leadership positions include president of local NC-AADR (North Carolina (2005-2006); director of the AADR Craniofacial Biology group (CBG) 2004-2007; IADR/AADR councilor for NC-AADR (2007, 2008, 2012) and for the CBG (2012-2015); member of Southern Association of Orthodontists Scientific Affairs Committee (2005-2013) and the American Association of Orthodontists Council on Scientific Affairs (2014 ­ Present). Dr. Frazier-Bowers also serves various editorial boards including the Journal of Dental Research and the Scientific Advisory board for the Consortium on Orthodontic Advances in Science and Technology. Her current role as faculty at UNC-CH includes conducting human genetic studies to determine the etiology of inherited tooth disorders, mentoring students at all levels, teaching graduate and pre-doctoral level Growth and Development courses and treating patients in the UNC School of Dentistry faculty practice in Orthodontics.

Induced ankylosis of a primary molar for skeletal anchorage in the mandible as alternative to mini-implants.

BACKGROUND: Mesial protraction of mandibular posterior teeth requires increased anchorage to avoid undesired tooth movements. Orthodontic mini-implants have become a popular and successful way to increase skeletal anchorage in such cases. However, mini-implants may cause injury to adjacent teeth or anatomical structures and may lead to tissue inflammation. Induced ankylosed primary teeth have been used in the past as abutments for the protraction of the maxilla in cases of maxillary retrognathism. However, this technique has not been described in the literature for the protraction of mandibular molars. The aim of this paper is to present, through a case report, an alternative to mini-implant devices to maximize anchorage in the mandible by inducing ankylosis on a primary molar. FINDINGS: A 13-year-old female with class II right malocclusion, deep bite, and congenitally missing right second premolars was referred for orthodontic treatment. Treatment plan involved removal of the primary teeth and mesial protraction of the posterior. In the mandible, ankylosis was induced on the retained primary second molar by extraction, bisection, replantation of the mesial part after endodontic treatment, and bonding of a rigid splint. Ankylosis was diagnosed after 10 weeks and a closing T-loop sectional wire was inserted to move the permanent first molar mesially. At 6 months, the remaining space was closed using elastic chain on a rectangular stainless steel wire with tip-back bends, supported by class II elastics. CONCLUSIONS: Induced ankylosis of primary teeth can be an alternative to orthodontic mini-implants in selected cases, with minimal risks and maximum biocompatibility.

Denervation resulting in dento-alveolar ankylosis associated with decreased Malassez epithelium.

Inferior alveolar nerve denervation causes appreciable decreases in the distribution of epithelial rests of Malassez. To explore roles of the Malassez epithelium, we attempted to evaluate possible changes in dento-alveolar tissues surrounding this epithelium by experimental denervation. We found that denervation led to dento-alveolar ankylosis with a decrease in the width of the periodontal spaces. Interestingly, with regeneration of the Malassez epithelium 10 weeks after the denervation, the periodontal space width showed a correspondingly significant increase. These findings suggest that the Malassez epithelium may be involved in the maintenance of periodontal space and that sensory innervation might be indirectly associated with it. In addition, it is of interest that denervation activated root resorption of the coronal root surface and that the consequently resorbed lacunae were repaired by cellular cementum. It is suggested that Malassez epithelium may negatively regulate root resorption and induce acellular cementum formation.

Periodontal repair in dogs: a bioabsorbable calcium carbonate coral implant enhances space provision for alveolar bone regeneration in conjunction with guided tissue regeneration.

BACKGROUND: Collapse or compression of a barrier device into a periodontal defect or onto the root surface compromises outcomes following guided tissue regeneration (GTR). Bone biomaterials have been suggested to support regeneration of alveolar bone and to improve space provision with GTR devices. The objective of this study was to evaluate space provision, alveolar bone, and cementum regeneration following use of a bioabsorbable, calcium carbonate biomaterial in conjunction with GTR. METHODS: Routine, critical size, 5 to 6 mm, supraalveolar, periodontal defects were created in 5 young adult beagle dogs. Alternate jaw quadrants in consecutive animals received GTR and the coral biomaterial (cGTR) or GTR alone. The animals were euthanized 4 weeks postsurgery and tissue blocks processed for histometric analysis. RESULTS: The coral implant particles were surrounded by newly-formed bone or immersed in connective tissue and appeared to resorb and be replaced by bone. There was limited, if any, appreciable cementum regeneration. Space provision was enhanced in cGTR compared to GTR sites (6.1 +/- 1.6 versus 2.4 +/- 0.8 mm2; P<0.05). Bone regeneration (height) was significantly increased in cGTR compared to GTR sites averaging 1.9 +/- 0.6 and 1.2 +/- 0.6 mm, respectively (P<0.05). Bone regeneration (area) was 2-fold greater in cGTR sites compared to the GTR control (3.3 +/- 1.8 versus 1.4 +/- 0.5 mm2), however the difference was not statistically significant (P>0.05). CONCLUSIONS: The coral implant significantly enhanced space provision for GTR while alveolar bone formation appeared to be enhanced by its use. Increased healing intervals are needed to fully understand the biologic value of the coral implant as an adjunct to GTR.

Effects of occlusal loading on ankylosis, bone, and cementum formation during bone morphogenetic protein-2-stimulated periodontal regeneration in vivo.

BACKGROUND: The purpose of this study was to investigate the influence of occlusal loading on recombinant human bone morphogenetic protein-2 (BMP-2)-induced bone and cementum formation in a previously established rat model of periodontal regeneration during the early and late stages of wound healing. METHODS: 64 Wistar rats were divided into 8 groups and had surgically created fenestrated defects on the right side of the mandible involving the removal of bone and exposure of the first and second molar roots. Four groups had their right maxillary molars extracted 2 weeks prior to surgery. Ten microl of 100 ug/ml BMP-2 in a collagen membrane was placed in extracted (hypofunctional) and non-extracted (functional) groups (BMPe and BMPf, respectively) while control groups had collagen membrane only (CONe and CONf). Groups were sacrificed at 10 (BMPe, BMPf, CONe, CONf) or 35 days (BMP35e, BMP35f, CON35e, CON35f) postoperatively and tissues processed for histological examination. Transverse 5 microm sections were stained for identification of new bone, ankylosis and cementum formation. RESULTS: At 10 days, CONe developed greater bone growth compared with CONf (P<0.05), while both BMP groups developed greater bone compared with controls. However, BMPe developed more ankylosis compared with both CONe and CONf while BMPf was significantly greater than CONf only (P<0.05). BMPf only developed significantly greater new cementum compared with controls. At 35 days, BMP35f developed greater bone growth compared with all other groups including BMP35e (P<0.05) and unlike results at 10 days, no differences were apparent between CON35f and CON35e. Unwanted bone growth beyond the defect margin anteriorly was significantly greater in BMP35f. CONCLUSIONS: Results suggest hypofunction stimulates early bone formation. Furthermore, hypofunction and BMP-2 increase the development of transient ankylosis. However, after wound healing is complete, function augments the early effects of BMP-2-induced new bone growth indicating remodeling to physiological levels does not occur. Finally, occlusal loading is both an important stimulus for remodeling and establishment of the periodontal ligament space during early wound healing as well as enhancing BMP-2-induced cementogenesis.

Tooth resorption.

Tooth resorption is a common sequela following injuries to or irritation of the periodontal ligament and/or tooth pulp. The course of tooth resorption involves an elaborate interaction among inflammatory cells, resorbing cells, and hard tissue structures. The key cells involved in resorption are of the classic type, which include osteoblasts and odontoclasts. Types of tooth resorption include internal resorption and external resorption. There are two types of internal resorption: root canal (internal) replacement resorption and internal inflammatory resorption. External resorption can be classified into four categories by its clinical and histologic manifestations: external surface resorption, external inflammatory root resorption, replacement resorption, and ankylosis. External inflammatory root resorption can be further categorized into cervical resorption with or without a vital pulp (invasive cervical root resorption) and external apical root resorption. Other variations of resorption include combined internal and external resorption and transient apical breakdown.

Moving an ankylosed central incisor using orthodontics, surgery and distraction osteogenesis.

When a dentist replants an avulsed tooth, the repair process sometimes results in the cementum of the root and the alveolar bone fusing together, with the replanted tooth becoming ankylosed. When this occurs, the usual process of tooth movement with bone deposition and bone resorption at the periodontium cannot function. If dental ankylosis occurs in the maxillary incisor of a growing child, the ankylosed tooth also cannot move vertically with the subsequent vertical growth of the alveolar process. This results in the ankylosed tooth leaving the plane of occlusion and often becoming esthetically objectionable. This report describes a 12-year-old female with a central incisor that was replanted 5 years earlier, became ankylosed, and left the occlusal plane following subsequent normal vertical growth of the alveolar process. When growth was judged near completion, the tooth was moved back to the occlusal plane using a combination of orthodontics, surgical block osteotomy, and distraction osteogenesis to reposition the tooth at the proper vertical position in the arch. This approach had the advantage of bringing both the incisal edge and the gingival margin of the clinical crown to the proper height in the arch relative to their antimeres. Previous treatment procedures for ankylosed teeth have often involved the extraction of the affected tooth. When this is done, a vertical defect in the alveolar process results that often requires additional bone surgery to reconstruct the vertical height of the alveolar process. If the tooth is then replaced, the replacement tooth must reach from the final occlusal plane to the deficient ridge. This results in an excessively long clinical crown with a gingival height that does not match the adjacent teeth.

Bone dynamics of osseointegration, ankylosis, and tooth movement.

Masticatory function challenges the strength and adaptive capability of supporting bone. When osseous tissue is loaded, it accumulates fatigue damage which must be repaired by bone modeling and remodeling. The three principal masticatory abutments (normal teeth, ankylosed teeth and osseointegrated implants) are a dynamic physiologic continuum relative to bone biomechanics. Implants are rigidly integrated units that can only be moved by fracturing the interface. Normal teeth and some ankylosed teeth can be moved using implants for orthodontic and orthopedic anchorage. Because orthodontic translation generates new bone and attached gingiva, it is a form of tissue engineering. Modern interdisciplinary practice requires a thorough knowledge of the principles of bone physiology and biomechanics.

Dental implant success-failure analysis: a concept of implant vulnerability.

This article shows the factors of importance in the long-term success and failure of oral implants based on literature review. Many factors are attributed to the failure of dental implants. The critical components leading to early and late implant failures are evaluated. The behavior of natural teeth and implants is compared in healthy and unfavorable local and systemic conditions. Similarities and differences among dental implants, healthy natural teeth, and ankylosed teeth are examined. Based on this comparison, the author attempts to draw a conclusion on the vulnerability of dental implants and their prognosis. The importance of ongoing clinical supervision of a patient's implant condition with a good recall program and the necessity to accumulate clinical data concerning implant failures over an extended period of time in a standardized manner are emphasized. It is also suggested that implant practitioners avoid giving guarantees of long-term implant success to their patients.

A treatment decision-making model for infraoccluded primary molars.

The objective of this paper is to clarify the literature's findings and provide guidelines for decision-making during the long-term treatment planning of infraoccluded primary molars. This paper presents a synopsis of findings concerning prevalence, aetiology, diagnostic methods, diagnostic criteria and treatment options. Treatment decisions are mainly guided by the clinical assessment of the presence or absence of succedaneous tooth, evaluation of onset, time of diagnosis, resorption rate, rate of progression of infraocclusion, risk of adverse effects over time, and predictive clinical patterns of infraoccluded primary molars. These models are a result of a comprehensive review of the literature and presents a compilation of findings in a format that is of practical use to the clinician.