The effects of infraocclusion: Part 3. Dental arch length and the midline

Restorative dentistry clinical decision-making for hypodontia: retained primary molars

Primary molar teeth that are retained beyond their exfoliation pose a clinical decision-making challenge for dental teams. The retention of these teeth may be due to absence of a permanent successor. As a result, careful planning is required to determine if retention or extraction is necessary. This article aims to discuss the prevalence of retained primary molars, assessment and treatment planning considerations, from both orthodontic and restorative perspectives.

Treatment of ankylosed deciduous molars with or without permanent successors in children and adolescents: a systematic review

INTRODUCTION

The aim of this systematic review was to provide guidelines for decision-making during orthodontic treatment planning of infra-occluded deciduous molars with or without their successors in children and adolescents.

EVIDENCE ACQUISITION

Computerized search was conducted on Medline via PubMed, and Cochrane Library. Articles published until 2020 in English language were analyzed following the Preferred Reporting Items for Systematic Reviews (PRISMA) Checklist. Observational and interventional longitudinal studies reporting the treatment of ankylosed deciduous molars with or without successor tooth in 3 to 15-year-old patients were included.

EVIDENCE SYNTHESIS

In case of ankylosis with presence of successor, exfoliation took place in 77% of teeth, while extraction involved 23%. Infra-occlusion happened in 53% of teeth (worsening in 52%), alveolar bone loss in 37%, mesial tipping of first permanent molar in 5%, and over-eruption of antagonist in no cases (after exfoliation and eruption of successor). In case of ankylosis without successor, exfoliation took place in 1% of teeth, progression of infra-occlusion in 42%, progression of root resorption in 58%, development of mesial tipping of first permanent molars in 25%, while no case of antagonist over-eruption was reported.

CONCLUSIONS

When the permanent tooth is present and the ankylosed tooth is slightly or moderately infra-occluded, observation is appropriate. In case of severe infra-occlusion or absence of successor, tooth extraction may be considered together with orthodontic space closure, transplantation, or prosthetic replacement. Alternatively, nonextraction and a prosthetic build-up may be considered.

Analysis of the cells isolated from epithelial cell rests of Malassez through single-cell limiting dilution

The epithelial cell rests of Malassez (ERM) are essential in preventing ankylosis between the alveolar bone and the tooth (dentoalveolar ankylosis). Despite extensive research, the mechanism by which ERM cells suppress ankylosis remains uncertain; perhaps its varied population is to reason. Therefore, in this study, eighteen unique clones of ERM (CRUDE) were isolated using the single-cell limiting dilution and designated as ERM 1-18. qRT-PCR, ELISA, and western blot analyses revealed that ERM-2 and -3 had the highest and lowest amelogenin expression, respectively. Mineralization of human periodontal ligament fibroblasts (HPDLF) was reduced in vitro co-culture with CRUDE ERM, ERM-2, and -3 cells, but recovered when an anti-amelogenin antibody was introduced. Transplanted rat molars grown in ERM-2 cell supernatants produced substantially less bone than those cultured in other cell supernatants; inhibition was rescued when an anti-amelogenin antibody was added to the supernatants. Anti-Osterix antibody staining was used to confirm the development of new bones. In addition, next-generation sequencing (NGS) data were analysed to discover genes related to the distinct roles of CRUDE ERM, ERM-2, and ERM-3. According to this study, amelogenin produced by ERM cells helps to prevent dentoalveolar ankylosis and maintain periodontal ligament (PDL) space, depending on their clonal diversity.

A novel approach for building up infraoccluded ankylosed primary molars in cases of missing premolars: A case report

BACKGROUND

In cases of infraoccluded primary molars associated with agenesis of premolars, any treatment plan occasionally includes retention of the primary teeth for space preservation and future implant placement if needed. In these cases, building up the crowns to the occlusal line is necessary to prevent various clinical problems. The present case report describes in detail a novel but simple clinical approach for retention and building up of the crown of infraoccluded primary molars.

CASE REPORT/TECHNIQUE PRESENTATION

The technique is presented in a 14-year-old girl with nine missing permanent teeth. Orthodontic evaluation indicated space closure for five teeth and space maintenance in the remaining four second primary molars, three of them being infraoccluded. The technique included the following clinical steps: (a) elastic separators were placed proximally to the primary molars for few days to create space; (b) proximal minimal reduction of the crown width was performed; a direct hand composite resin core was made to increase crown height facilitating the selection of a preformed metal crown (PMC). The selected PMC was filled with self-curing composite resin and placed on the primary tooth following an acid etch and adhesive procedure; excess cervical material was removed; (c) after polymerisation, the PMC was carefully removed using cutting and hand instruments, revealing the composite resin fabricated crown which was adjusted for occlusion and polished. Radiographic evaluation confirmed the result.

CONCLUSION

This simple method for infraoccluded primary molars crown building up to occlusion using conventional instruments and materials, appears to be a valuable clinical tool for paediatric dentists who frequently find themselves dealing with primary teeth that need to be retained and which can produce serious clinical problems if left untreated.

Management of ankylosed primary molars with premolar successors: a systematic review

BACKGROUND

The authors conducted a systematic review to determine the clinical prognosis of and methods of managing ankylosed primary molars with permanent successors.

METHODS

The authors searched electronic databases (PubMed, Scopus, MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Cochrane Database of Systematic Reviews and Google Scholar) up to April 2012 with the assistance of a librarian specializing in health sciences databases. They also searched the gray literature. They selected clinical studies in which investigators assessed the prognosis of ankylosed primary molars with permanent successors; they also hand searched references of the selected articles to identify any additional studies that the electronic search may have missed.

RESULTS

The authors identified 3,529 original articles from the electronic database search and none from the hand search. Once selection criteria were applied, only four articles met all inclusion criteria and were included. The number of patients studied ranged from 15 to 107. The number of ankylosed primary molars investigated ranged from 26 to 263.

CONCLUSIONS

Ankylosed primary molars often manifest with mild to moderate progressive infraocclusion. Conservative monitoring of ankylosed primary molars is recommended. The clinician should consider extraction if the permanent successor has an altered path of eruption, if the ankylosed primary molar is severely infraoccluded with the adjacent teeth tipping to prevent the successor from erupting, or both. The ankylosed molar often exfoliates spontaneously within six months; however, when exfoliation is more delayed, arch-length loss, occlusal disturbance, hooked roots or impaction of permanent successors may occur. Practical Implications. Ankylosed primary molars initially should be monitored closely for up to six months. If they do not exfoliate spontaneously, they should be removed, because arch-length loss, alveolar bone defects, impacted permanent successors and occlusal disturbances often occur when the removal is delayed.

Ankylosis of permanent first molars: genetics or environment? A case report of a discordant twin pair

The rare condition of secondary retention has been reported in the literature as being of genetic origin, with some authors suggesting an autosomal dominant pattern. We report the unusual case of two monozygotic biamniotic, bichorionic male twins, who were discordant for permanent first molar secondary retention, involving ankylosis. Twin A showed normal occlusion and eruption patterns, whereas Twin B displayed a left open bite, in relation with a totally submerged primary second molar leading to retention of the underlying premolar (35), and severe infraocclusion of the adjacent permanent molar (36). After orthodontic failure to close the open bite, ankylosis of 36 was confirmed, whereas 26 became severely infraoccluded.The mother had a history of bilateral molar ankylosis and presented reduced posterior alveolar height. Discordance in this twin pair demonstrates that environmental influences, in addition to epigenetic and local factors, may play a role in secondary retention, which is difficult to diagnose and challenging to treat.

Orthosurgical treatment including anchorage from a palatal implant to correct an infraoccluded maxillary first molar in a young adult

Tooth ankylosis during adolescence and early adulthood can lead to infraocclusion and several interrelated, adverse sequelae at the intra-arch and interarch levels. An orthosurgical treatment modality that includes surgical luxation and immediate orthodontic traction is recommended as a conservative approach in many patients. The key to success in this approach is the timely delivery of relatively heavy and continuous forces to the luxated tooth to prevent its reankylosis. Because high reactive forces are inevitably generated, it is crucial to create a reliable source of anchorage. This report describes the successful use of an osseointegrated orthodontic implant to reinforce the anchorage during the orthosurgical repositioning of an infraoccluded molar in a young adult.

Late diagnosis of dentoalveolar ankylosis: impact on effectiveness and efficiency of orthodontic treatment

Dentoalveolar ankylosis is a local etiologic factor of malocclusion that can have deleterious effects on normal dental development. Therefore, it is of paramount importance to diagnose the problem as early as possible so that interception can be performed at the correct time. This case report demonstrates the consequences of late diagnosis of dentoalveolar ankylosis and discusses its effects on development of the occlusion and how it can increase orthodontic biomechanical complexity and treatment time.

Atypical retention of infraoccluded primary molars with permanent successor teeth

BACKGROUND

Infraocclusion of primary molar teeth is relatively common. The majority of infraoccluded primary molars with permanent successors exfoliate naturally. There are currently no evidence based guidelines for the treatment of infraoccluded primary molars with permanent successor teeth.

CASE SERIES

The three cases presented demonstrate atypical retention of infraoccluded primary molars, following a conservative approach. In case 1 taking a conservative approach over 5 years, the infraocclusion became gradually more severe. Tilting of the adjacent teeth and the centre-line shift caused by leaving the affected tooth in place during dental and alveolar development was significant. In Case 2 the severely infraoccluded 55 required surgical removal and exposure of the underlying permanent successor (15). Case 3 showed a maxillary premolar (14) and first permanent molar (16) tilted toward the partially erupted, ectopic, rotated 15. Surgical removal of the impacted maxillary primary molar was required.

CONCLUSION

Although there is evidence available to support the conservative treatment of such cases, it does not always lead to a favourable outcome. Detrimental effects on the adjacent teeth and occlusion were observed and surgical intervention was required.

Diagnosis and management of the infraerupted primary molar

An infraerupted tooth is a tooth that has failed to erupt to be in line with adjacent teeth in the vertical plane of occlusion. The general dentist may be faced with this predicament which requires careful attention and thoughtful consideration in terms of long-term patient goals. It is important to diagnose infraerupted teeth and treat them in a timely fashion to help prevent unwelcome sequelae. Important interdisciplinary communication is vital between the dentist and the orthodontist to ensure that precious space and time are not lost. Here we present a review article of complications and considerations that must be taken into account when faced with a patient who has an infraerupted tooth.

Orthosurgical treatment with lingual orthodontics of an infraoccluded maxillary first molar in an adult

The biological mechanism that leads to a cessation in the normal passive eruption of a tooth is unclear, and there are differing views as to whether ankylosis is involved. When infraocclusion of a permanent molar occurs in the permanent dentition, its effects are seen (1) locally, with exaggerated tipping and relative under-eruption of the adjacent teeth; (2) regionally, with overeruption of the opposing tooth or teeth; and (3) farther afield, with deviation of the dental midline to the affected side. Treatment aimed at eliminating these adverse conditions is warranted, and this might involve the skills of both an orthodontist and an oral surgeon. When the condition occurs in an adult, the changes in facial appearance that will be caused by traditional fixed orthodontic appliances might undermine the patient's willingness to accept treatment. This report describes the successful orthosurgical treatment with lingual orthodontics of an infraoccluded maxillary first molar in an adult. The challenges, treatment alternatives, and technical refinements are emphasized.