Continuous Tooth Eruption Research Articles

Implant placement in the aesthetic zone: Long-term results.

SUMMARY: Implant placement is considered to be a routine procedure for oral rehabilitation, in cases of tooth agenesia or tooth loss (due to factors such as periodontitis, trauma,caries). Dental implants’ position does not change over time due to the process of “osseointegration”. On the contrary, teeth follow craniofacial growth (in particular, orofacial and dentoalveolar growth) and move. The stomatognathic system undergoes changes in its vertical and horizontal dimensions after adulthood. Implant placement on the anterior maxilla is challenging for clinicians, because of continuous eruption of adjacent teeth, as well as, due to occurrence of occlusal changes. Long-term aesthetic complications, such as differences in incisal edges’ length, position of gingival margins and open contact points between implant restorations and adjacent teeth, should be taken into consideration. The aim of this study is to review literature concerning long-term complications after implant placement in the anterior maxilla. Furthermore, 2 case reports concerning aesthetic problems of implant restorations in the esthetic zone will be presented, together with their treatment procedure. Consequently, with time, implant restorations in the anterior maxilla present aesthetic complications of various degrees, which are in need of personalized treatment plan. In order to avoid such complications, implant placement is recommended to be performed after completion of skeletal growth and maturation.

Is Continuous Eruption Related to Periodontal Changes? A 16-Year Follow-up

The aims of this study were to 1) determine if continuous eruption occurs in the maxillary teeth, 2) assess the magnitude of the continuous eruption, and 3) evaluate the effects of continuous eruption on the different periodontal parameters by using data from the population-based cohort of the Study of Health in Pomerania (SHIP). The jaw casts of 140 participants from the baseline (SHIP-0) and 16-y follow-up (SHIP-3) were digitized as 3-dimensional models. Robust reference points were set to match the tooth eruption stage at SHIP-0 and SHIP-3. Reference points were set on the occlusal surface of the contralateral premolar and molar teeth, the palatal fossa of an incisor, and the rugae of the hard palate. Reference points were combined to represent 3 virtual occlusal planes. Continuous eruption was measured as the mean height difference between the 3 planes and rugae fix points at SHIP-0 and SHIP-3. Probing depth, clinical attachment levels, gingiva above the cementoenamel junction (gingival height), and number of missing teeth were clinically assessed in the maxilla. Changes in periodontal variables were regressed onto changes in continuous eruption after adjustment for age, sex, number of filled teeth, and education or tooth wear. Continuous tooth eruption >1 mm over the 16 y was found in 4 of 140 adults and averaged to 0.33 mm, equaling 0.021 mm/y. In the total sample, an increase in continuous eruption was significantly associated with decreases in mean gingival height (B = −0.34; 95% CI, −0.65 to −0.03). In a subsample of participants without tooth loss, continuous eruption was negatively associated with PD. This study confirmed that continuous eruption is clearly detectable and may contribute to lower gingival heights in the maxilla.

Unique Tooth Morphology and Prismatic Enamel in Late Cretaceous Sphenodontians from Argentina.

Mammals and reptiles have evolved divergent adaptations for processing abrasive foods. Mammals have occluding, diphyodont dentitions with taller teeth (hypsodonty), more complex occlusal surfaces, continuous tooth eruption, and forms of prismatic enamel that prolong the functional life of each tooth [1, 2]. The evolution of prismatic enamel in particular was a key innovation that made individual teeth more resilient to abrasion in early mammals [2-4]. Incontrast, reptiles typically have thin, non-prismatic enamel, and shearing, polyphyodont dentitions with multi-cusped or serrated tooth crowns, multiple tooth rows, rapid tooth replacement rates, or batteries made of hundreds of teeth [5-9]. However, there are rare cases where reptiles have evolved alternative solutions to cope with abrasive diets. Here, we show that the combined effects of herbivory and an ancestral loss of tooth replacement in a lineage of extinct herbivorous sphenodontians, distant relatives of the modern tuatara (Sphenodon punctatus) [10], are associated with the evolution of wear-resistant and highly complex teeth. Priosphenodon avelasi, an extinct sphenodontian from the Cretaceous of Argentina, possesses a unique cone-in-cone dentition with overlapping generations of teeth forming a densely packed tooth file. Each tooth is anchored to its predecessor via a rearrangement of dental tissues that results in a novel enamel-to-bone tooth attachment. Furthermore, the compound occlusal surfaces, thickened enamel, and the first report of prismatic enamel in a sphenodontian are convergent strategies with those in some mammals, challenging the perceived simplicity of acrodont dentitions [11-15] and showcasing the reptilian capacity to produce complex and unusual dentitions.

Occlusal Migration of Teeth Adjacent to Implant Prostheses in Adults: A Long-Term Study.

To evaluate the effect of continuous tooth eruption on the outcomes of single-implant-supported restorations in the anterior maxilla of adults. Seventy-six patients (age: 21 to 78 years) treated with single-implant-supported restorations in the esthetic zone were included. Radiographs obtained at crown placement and follow-up examinations from 1 to 15 years postloading were analyzed with regard to vertical incisal plane changes of the implant-supported crown relative to adjacent teeth. Infraocclusion increased over time by 0.08 ± 0.02 mm/year. Infraocclusion was more pronounced (P = .04) for delayed (0.09 mm/year) versus immediate implant placement (0.06 mm/year) and for younger versus older adults (0.0013 mm/year per additional year of age; P = .014). No statistically significant association between infraocclusion and sex, ethnicity, implant site, timing of implant temporization, surgical protocol, and type of restoration was found. Infraocclusion of single-implant-supported maxillary anterior restorations may result in esthetic concerns over time. Greater infraocclusion occurs in delayed implant placement and in younger individuals.

Continuous eruption of maxillary teeth and changes in clinical crown length: A 10-year longitudinal study in adult women.

Continuous physiologic eruption of teeth may become a main aesthetic issue for implants inserted in the maxillary anterior region. To study maxillary tooth vertical changes during a 10 years period by 3-dimensional superimposition of digital dental casts. Alginate impressions were taken at both baseline and at the 10-year follow-up in a sample of 24 adult Swedish women (average age of 48 years at T0). The upper arch plaster casts were digitized with a 3-dimensional scanner and then superimposed on the palate and the palatal rugae. Occlusal and gingival anatomic structures were digitized for each upper tooth from first molar to first molar. The vertical changes of these structures gave an indication of tooth extrusion and apical or coronal displacement of the gingival margin. A trend was found for eruption in the anterior region (+0.3 mm on average) while a slight extrusion if not any was found in the first molars and premolars area. Vertical displacement of the gingival margin showed also a positive trend from first molars to incisors. Negative average values, corresponding clinically to gingival recession, were found on first molars (-0.36 mm) and premolars (-0.15 mm), while no displacement was detected in the anteriors. Clinical crown lengths increased in all teeth and it is mainly due to gingival recession for first molars and premolars, while for the incisors the eruption is coupled to a slight equivalent gingival coronal migration. During a 10-year period, continuous eruption takes place in female adult subjects, especially in the upper incisors area while gingival recession occurred in first molars and premolars area leading to crown length elongation. Implant placement in the anterior area of the maxilla may have an aesthetic impact even in mature adults due to the continuous eruption of the adjacent teeth.

Facial development and continuous tooth eruption as compromising factors for implant placement

Facial development and continuous tooth eruption as compromising factors for implant placement

SM50 repeat-polypeptides self-assemble into discrete matrix subunits and promote appositional calcium carbonate crystal growth during sea urchin tooth biomineralization

The two major proteins involved in vertebrate enamel formation and echinoderm sea urchin tooth biomineralization, amelogenin and SM50, are both characterized by elongated polyproline repeat domains in the center of the macromolecule. To determine the role of polyproline repeat polypeptides in basal deuterostome biomineralization, we have mapped the localization of SM50 as it relates to crystal growth, conducted self-assembly studies of SM50 repeat polypeptides, and examined their effect on calcium carbonate and apatite crystal growth. Electron micrographs of the growth zone of Strongylocentrotus purpuratus sea urchin teeth documented a series of successive events from intravesicular mineral nucleation to mineral deposition at the interface between tooth surface and odontoblast syncytium. Using immunohistochemistry, SM50 was detected within the cytoplasm of cells associated with the developing tooth mineral, at the mineral secreting front, and adjacent to initial mineral deposits, but not in muscles and ligaments. Polypeptides derived from the SM50 polyproline alternating hexa- and hepta-peptide repeat region (SM50P6P7) formed highly discrete, donut-shaped self-assembly patterns. In calcium carbonate crystal growth studies, SM50P6P7 repeat peptides triggered the growth of expansive networks of fused calcium carbonate crystals while in apatite growth studies, SM50P6P7 peptides facilitated the growth of needle-shaped and parallel arranged crystals resembling those found in developing vertebrate enamel. In comparison, SM50P6P7 surpassed the PXX24 polypeptide repeat region derived from the vertebrate enamel protein amelogenin in its ability to promote crystal nucleation and appositional crystal growth. Together, these studies establish the SM50P6P7 polyproline repeat region as a potent regulator in the protein-guided appositional crystal growth that occurs during continuous tooth mineralization and eruption. In addition, our studies highlight the role of species-specific polyproline repeat motifs in the formation of discrete self-assembled matrices and the resulting control of mineral growth.

Vertikal Boyut Yükseltilerek Yapılan Protetik Rehabilitasyon

Tooth wear can be classified according to its cause; attrition, abrasion and erosion. Tooth wear is considered pathologic when an intervention is necessary for cosmetic or functional purposes. It is important to determine the factors of tooth wear for treatment protocols. A differential diagnosis is not always possible because there may be a combination of these processes occuring. Lost of vertical dimension can cause loss of posterior support, reduce of interocclusal distance and change of fasial appearance. Loss of tooth structure does not necessarily mean loss of vertical dimension of occlusion. Loss of vertical dimension of occlusion caused by physiologic tooth wear is usually compensated by continuous tooth eruption and alveoler bone growth. In this case report, a treatment to recover lost of masticatoring function and vertical dimension has been described that a patient who has excessive wear of the teeth.

Radiological evaluation of single implants in maxillary anterior sites with special emphasis on their relation to adjacent teeth – a 3‐year follow‐up study

The aim of this study was to measure, in adults, changes in crest bone level around single dental implants in the anterior maxilla and continuous eruption of adjacent teeth. In this prospective study, 50 patients received single-implant-supported crowns in the maxillary anterior region. Enrolled patients lacked maxillary anterior teeth as a sequel to trauma or agenesis in the maxillary anterior region. Participants were followed during a 3-year period. Baseline radiographs were taken at the time of loading and then repeated at one- and 3-year recalls. Radiographic parameters were recorded to assess changes in the skeletal bone structure and crest bone level. Twenty-six patients attended for all recalls. Three patients were excluded owing to difficulties related to identifying the same radiographic landmark on the radiographs throughout the recall period. All implants were successfully integrated with no sign of peri-implantitis. The mean crest bone loss was 0.45mm at the mesial aspect of the implant and 0.56mm at the distal aspect. In smokers, there was significant bone loss on the distal aspect. Mean change between reference points on implant and adjacent tooth (continuous eruption of adjacent tooth) over the 3-year period was 0.67mm. In women, mean change (0.79mm) was statistically insignificantly higher, compared with men (0.59mm). Radiographic evaluation of crest bone level showed slight bone loss after 3years of functional loading. Some changes in the eruption of neighbouring teeth were seen. Being a smoker was associated with significant negative changes related to the crest bone level.

Longitudinal Changes in Tooth/Single‐Implant Relationship and Bone Topography: An 8‐Year Retrospective Analysis

To evaluate longitudinal changes in tooth/implant relationship and bone topography at single implants with a microthreaded, conical marginal portion (Astra Tech ST® implants, Astra Tech AB, Mölndal, Sweden). Thirty-one subjects with single implant-supported restorations in the esthetic zone were included. Radiographs obtained at crown installation and 1, 5, and 8 years of follow-up were analyzed with regard to changes in (1) bone level at the implant and adjacent teeth and (2) vertical position of adjacent teeth relative to the single implant. The mean marginal bone loss amounted to 0.1 mm at both implants and adjacent teeth during the 8 years of follow-up. Regression analysis failed to identify significant explanatory factors for observed variance in bone level change at the adjacent tooth surfaces. Vertical change in position of the teeth relative to the implants was more frequent and significantly greater in incisor compared with premolar tooth region but not associated with gender or age. The marginal bone level at teeth adjacent to single implants with a microthreaded conical marginal part was not influenced by horizontal and vertical tooth-implant distances. Continuous eruption of adjacent teeth may result in infraocclusal positioning of a single-implant restoration.

Osteopontin is required for unloading-induced osteoclast recruitment and modulation of RANKL expression during tooth drift-associated bone remodeling, but not for super-eruption

Unloading of teeth results in extensive alveolar bone remodeling, causing teeth to move in both vertical (“super-eruption”) and horizontal direction (“drift”). In order to decipher the molecular mechanisms of unloading-induced bone remodeling during tooth movement, we focused on the role of osteopontin (OPN) in the un-opposed molar model, comparing wild-type (WT) and OPN-null mice. Our data indicated that OPN was not required for the continuous eruption of un-opposed teeth while OPN was necessary for the drift of teeth. OPN expression and osteoclast counts were greatly increased on alveolar bone surfaces facing the direction of the drift in WT mice, while osteoclast counts were diminished in OPN−/− mice. RANKL expression in the distal periodontal ligament of WT molars increased significantly by day 6 following unloading, while overall levels of RANKL expression were decreased in both WT and OPN-null mice. In vitro treatment of MC3T3 cells, WT BMCs and OPN−/− BMCs with recombinant OPN resulted in significantly increased RANKL expression in all three cell types. The PI3K and MEK/ERK pathway inhibitors Ly294002 and U0126 reduced RANKL expression levels in vitro. Treatment of BMCs and MC3T3 with OPN also resulted in increased ERK phosphorylation and reduced OPG levels. Together, our studies suggest that increased OPN expression during unloading-induced drifting of teeth enhances localized RANKL expression and osteoclast activity on drift-direction alveolar bone surfaces via extracellular matrix signaling pathways.

Facial development, continuous tooth eruption, and mesial drift as compromising factors for implant placement

The replacement of teeth lost by children because of trauma can be an important indication for early implant therapy. Osseointegrated dental implants, like ankylosed teeth, alter position as growth-related changes occur within the jawbones (displacement, remodeling, mesial drift). Facial growth of the child and even of the adolescent, as well as the continuous eruption of the adjacent anterior teeth, create significant risk of a less favorable esthetic and/or functional outcome. For patients with a normal facial profile, the placement of an implant should be postponed until growth is complete. For patients with a short or long face type, further growth, especially the continuous eruption of adjacent teeth, creates a serious risk even after the age of 20 years, as illustrated by some recent clinical studies. This review aims to explain these phenomena and provides some recommendations for implant placement.

Scanning electron microscopy of the three different types of cementum in the molar teeth of the guinea pig

The aim of this study was to observe the three-dimensional distribution and structural characteristics of the three different types of cementum in the molar teeth of guinea pig by means of scanning electron microscopy. Twenty-five 4-week-old male guinea pigs were used in this study. Using decalcified and undecalcified specimens with or without NaOH maceration, we examined the mandibles, maxillae and extracted molars by scanning electron microscopy. Guinea pig molars consist of two longitudinal, deeply folded lamina cores covered by enamel on all surfaces, except the buccal surface of the upper molars and the lingual surface of the lower molars. In the regions without enamel, we observed continuous thin belt-like layers of conventional acellular cementum on the dentin surface. On the enamel-covered surfaces, two different types of coronal cementum were found: small circular islands of coronal cementum called cementum pearls, which were distributed widely at almost regular intervals on the peripheral enamel surface from the apical fifth to the occlusal surface; and cartilage-like cementum, which occupied almost all of the occlusal half of the two longitudinally folded grooves. The present study demonstrated the unique distribution pattern of the three different types of cementum in guinea pig molars. These cementum types may contribute to the requirements for many different functions such as mastication, anchorage and continuous tooth eruption.

Orthodontic aspects of the use of oral implants in adolescents: a 10-year follow-up study.

The aim of the present study was to evaluate the long-term effect of implants installed in different dental areas in adolescents. The sample consisted of 18 subjects with missing teeth (congenital absence or trauma). The patients were of different chronological ages (between 13 and 17 years) and of different skeletal maturation. In all subjects, the existing permanent teeth were fully erupted. In 15 patients, 29 single implants (using the Brånemark technique) were installed to replace premolars, canines, and upper incisors. In three patients with extensive aplasia, 18 implants were placed in various regions. The patients were followed during a 10-year period, the first four years annually and then every second year. Photographs, study casts, peri-apical radiographs, lateral cephalograms, and body height measurements were recorded at each control. The results show that dental implants are a good treatment option for replacing missing teeth in adolescents, provided that the subject's dental and skeletal development is complete. However, different problems are related to the premolar and the incisor regions, which have to be considered in the total treatment planning. Disadvantages may be related to the upper incisor region, especially for lateral incisors, due to slight continuous eruption of adjacent teeth and craniofacial changes post-adolescence. Periodontal problems may arise, with marginal bone loss around the adjacent teeth and bone loss buccally to the implants. The shorter the distance between the implant and the adjacent teeth, the larger the reduction of marginal bone level. Before placement of the implant sufficient space must be gained in the implant area, and the adjacent teeth uprighted and paralleled, even in the apical area, using non-intrusive movements. In the premolar area, excess space is needed, not only in the mesio-distal, but above all in the bucco-lingual direction. Thus, an infraoccluded lower deciduous molar should be extracted shortly before placement of the implant to avoid reduction of the bucco-lingual bone volume. Oral rehabilitation with implant-supported prosthetic constructions seems to be a good alternative in adolescents with extensive aplasia, provided that craniofacial growth has ceased or is almost complete.

Mineral content of calcified tissues in cystic fibrosis mice.

Although abnormal hard tissue mineralization is a recognized complication of cystic fibrosis (CF), the pathogenesis leading from the defective cystic fibrosis transmembrane conductance regulator (CFTR) protein is poorly understood. We hypothesized that CFTR plays a direct role in the mineralization of bone and teeth and tested the hypothesis using CF mouse models [CFTR(-) mice]. In vivo measurements by dual-emission X-ray absorpitometry (DEXA) indicated that bone mineral density (BMD) was reduced in CF mice as compared to gender-matched littermates. However, no change was evident after correction of BMD for the covariant of body weight. The latter finding was confirmed in isolated femurs and nasal bones by standard dry-ashing and instrumental neutron activation analysis (INAA). INAA of the continuously growing hypsodont incisor teeth from CFTR(-) mice revealed reduced Ca and normal P in the enamel layer--a finding consistent with changes in the deciduous teeth of CF children. Interestingly, enamel fluoride was increased in the CFTR(-) incisors and may associate with abnormal enamel crystallite formation. The iron content of the incisor enamel was reduced, explaining the loss of yellow pigmentation in CFTR(-) incisors. In contrast to the incisors, the mineral content of the slow-growing brachydont molar teeth was not different between CFTR(-) and CFTR(+) mice. It was concluded that CFTR does not play a direct role in the mineralization of bones or brachydont teeth in mice. Functional CFTR is apparently required for normal mineralization of the hypsodont incisors. However, multiple changes in the mineral composition of the CF incisors suggest an indirect role for CFTR, perhaps by maintaining a normal salivary environment for continuous tooth eruption.

Continuous tooth eruption in Australian aboriginal skulls

Increases in the distance from the cemento-enamel junction to the alveolar crest (CEJ-AC) have often been attributed to senile atrophy of the bone or to the effects of periodontitis, without reference to the condition of the alveolar crest. This study investigated the relationship between CEJ-AC distance, tooth wear, gender, site of the CEJ-AC measurements, and age in 161 pre-white-contact Australian aboriginal skulls. Individual teeth were included in the study when there was no evidence of dehiscence, periodontitis, or abscess cavity formation in the supporting alveolar bone. The CEJ-AC distances increased as the severity of attrition increased; in male skulls, CEJ-AC distances were greater than in female skulls for all categories of tooth wear. In general, CEJ-AC distances measured on the mesial aspects of teeth were greater than those recorded distally; lingual distances generally exceeded buccal recordings. The best explanation of these findings and similar reports in the anthropological literature is that continuous tooth eruption occurred without the concomitant coronal movement of alveolar bone. This conclusion has significant ramifications for anthropological, epidemiological, and clinical studies which use the CEJ and AC as reference points when measuring periodontal attachment loss (periodontitis).

Tooth dislocation: The relationship with tooth wear and dental abscesses

Tooth dislocation (tilting) was recorded in 1,200 skulls from 34 museum collections. The findings of dislocation by tooth type, tooth wear, and abscess location are presented. A model for dislocation based upon the progressive loss of tooth support provides a rational explanation for the phenomenon. Physiological continuous tooth eruption was considered to account for a component of the progressive loss of tooth attachment. The process of attrition, pulp perforation, and dental abscess cavity formation resulted in further, more severe loss of tooth support. Heavy functional forces, in association with greatly reduced bone support, tilted the crown lingually and root buccally. When the tooth had tilted to such an extent that the root apices protruded from the bone and, presumably (in life) through the gingival/mucosal tissues, the infected root canals were effectively isolated from the internal environment. The tooth continued to function. The more typical consequence of severe attrition and dental abscess formation was tooth loss; it also isolated an infected tooth from living tissue, but without the benefit of retaining function.

Endogenous tooth movement

The three types of endogenous tooth movement are (1) the continuous eruption of teeth, (2) migration due to inherent weakness of the attachment apparatus, and (3) the adaptive movements of the teeth. Adaptive tooth movement is controlled by: (1) the contact relationships between adjacent and opposing teeth, and (2) the interaction of the components of the masticatory musculature. Knowledge of the various patterns of tooth movement is important to the practice of all phases of dentistry.