Drifting of teeth in the mandible studied in adult human autopsy material

Early Implant Bone Loss in the Preprosthetic Phase: A Retrospective Study

Initiation of the inflammatory response begins with the surgical placement of an implant that stimulates bone remodeling. The occurrence of crestal bone loss during submerged healing affects the prognosis of an implant. Hence, this study was conducted to estimate the early implant bone loss during the preprosthetic phase on bone level implants placed equicrestally. This retrospective observational study included evaluation of crestal bone loss around 271 two-piece implants placed in 149 patients from the archived postsurgical (P1) and preprosthetic (P2) digital orthopantomographic records using MicroDicom software. The outcome was categorized based on (1) sex (male or female), (2) time of implant placement (immediate [I] vs conventional [D]), (3) duration of healing period before loading (conventional [T1] vs delayed [T2]), (4) region of implant placement (maxilla [M1] vs mandible [M2]), and (5) site of implant placement (anterior [A] vs posterior [P]). To find the significant difference between the bivariate samples in the independent groups, an unpaired sample t test was used. The average marginal bone loss during the healing phase was 0.56 ± 0.573 mm in the mesial region and 0.44 ± 0.549 mm in the distal region of the implant, with a statistically significant difference (P < .01). There was no statistically significant difference in crestal bone level with the (1) sex of the patient (male or female), (2) type of implant placement (I or D), (3) time of implant loading (T1 or T2), (4) region of implant placement (M1 or M2), or (5) site of implant in the arch (A or P) (P > .05). An average of 0.50 mm crestal bone loss occurred in the peri-implant region during the preprosthetic phase. We found that the delayed placement of an implant and a delay in the healing period would further increase the early implant bone loss. The difference in the healing period did not alter the outcome of the study.

Proximal Contact Loss in Implant-Supported Restorations: A Systematic Review and Meta-Analysis of Prevalence

PURPOSE

This is a systematic review and meta-analysis to estimate the overall prevalence of proximal contact loss (PCL) and determine the distribution and clinical features of PCL.

METHODS

This systematic review was conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. As this was a systematic review of prevalence, the condition, context, and population framework was followed. The focus question was: What is the prevalence and distribution of PCL in implant-supported restorations? Two investigators independently examined the literature in four databases (Medline, Scopus, Web of Science, and Cochrane) for suitable articles published before November 11, 2020, with no start-date restriction; an additional search was conducted by hand. A standardized data extraction chart was utilized to extract the relevant information from the selected studies.

RESULTS

Fifteen studies met the inclusion criteria. A total of 11,699 restorations were evaluated in the final sample. The overall prevalence was 20% at the implant restoration level (among 4984 implants) and 26.6% at the contact point level (among 2603 contact points). The frequency of PCL was higher on the mesial side, both at the implant restoration level (13.8%) and at the contact point level (21.9%), than on the distal side, where the prevalence was 3.3% and 11.0%, respectively. The event rate in the maxilla and in the mandible at the contact level was 21.4% and 21.9%, respectively.

CONCLUSIONS

PCL is a frequent complication. Approximately 29% of contact points develop this condition, which may cause food impaction and damage to the interproximal tissues.

Interproximal contact loss between implant-supported restorations and adjacent natural teeth: A retrospective cross-sectional study of 83 restorations with an up to 10-year follow-up

STATEMENT OF PROBLEM

Interproximal contact loss between implant-supported restorations and adjacent natural teeth is a frequently encountered complication that could negatively affect surrounding tissues and/or patient satisfaction with treatment. The effect of interproximal contact loss on peri-implant tissue health and patient awareness of food impaction is currently unknown.

PURPOSE

The purpose of this retrospective cross-sectional study was to explore the effect of interproximal contact loss on peri-implant tissue health and determine whether interproximal contact loss leads to increased patient awareness of food impaction around the affected area. This study also aimed to identify whether specific patient or local factors could cause interproximal contact loss.

MATERIAL AND METHODS

Eighty-three participants with posterior single-unit implant-supported restorations were examined. The mean follow-up time after prosthesis insertion was 4 ±2.2 years (range 4 months to 10.6 years). Interproximal contacts were evaluated by using waxed dental floss. Patient age, sex, implant location, opposing tooth status, presence of endodontically treated adjacent tooth, and regular use of an occlusal device at night were recorded. Peri-implant probing depths and the presence of bleeding on probing were also recorded. Each participant was asked to indicate whether they had noticed increased food impaction around their implant-supported restoration. Statistical analysis included nonparametric Mann-Whitney U tests, the Spearman rank-order correlation, the Pearson chi-squared tests, and the paired t test (α=.05).

RESULTS

Among all examined mesial contacts, 34.1% were recorded as open, with an overall mesial interproximal contact loss (open and loose contacts combined) incidence of 48.8%. Restorations placed in premolar sites exhibited significantly tighter mesial interproximal contacts compared with those placed in molar sites (U=566, P=.041). A significant negative correlation was found between follow-up time after insertion and mesial contact tightness (r_s=-0.226, P=.041).

CONCLUSIONS

Interproximal contact loss appears to increase over time, with more surfaces being affected after longer periods of service. This study did not find an association between interproximal contact loss and peri-implant inflammation as measured by bleeding on probing, with the exception of the distolingual implant surface. Participants with interproximal contact loss were more aware of food impaction around their implant crown. Use of an occlusal device at night did not prevent interproximal contact loss.

Corticotomy affects both the modus and magnitude of orthodontic tooth movement

Objective

To analyze whether the decreased bone density due to the manipulation of bone remodeling rate has an influence on the type of the planned tooth movement.

Materials and methods

A finite element model of a lower incisor has been developed. The density of the alveolar bone surrounding the tooth has been assumed to simulate the one occurring after corticotomy to increase tooth movement rate. Moment-to-force ratios corresponding to three different types of movements have been simulated; uncontrolled tipping, translation, and root movement. The three tooth movements have been analyzed in both corticotomized and non-corticotomized simulations, and the final effects on the amount and type of tooth movement analyzed. The stress and strain levels in the periodontal ligament have been analyzed too.

Results

The amount of tooth movement obtained in case of lower bone density is higher in all types of movement simulations. The centre of rotation of the movement shifts more apically in case of translation, controlled and uncontrolled tipping. In the corticotomy simulations, the compressive stresses in the periodontal ligament decreased while the tensile stresses increased.

Conclusion

A decreased bone density influences not only the amount of tooth movement, but also its type. This study suggests that the moment-to-force ratios used in conventional orthodontics should be modified in case of techniques that decrease bone density to enhance tooth movement rate.

The rise and fall of the alveolar process: Dependency of teeth and metabolic aspects

The alveolar bone has a unique capacity to follow the teeth's movements. It is formed around erupting teeth and their periodontal ligaments: the more the teeth have erupted, the larger the alveolar process. Throughout life the teeth erupt and migrate in an occlusal and mesial direction to compensate for attrition, an evolutionary trait. After tooth extraction, the alveolar process is resorbed to varying degrees. The mandibular alveolar bone mirrors skeletal bone condition. Due to fast bone turnover (which is the fastest in the whole skeleton), low bone mass and increased fracture risk may first be seen here. If a periapical radiograph of the mandibular premolars shows a dense trabeculation with well-mineralized trabeculae and small intertrabecular spaces, it is a reliable sign of normal skeletal bone density (BMD) and low skeletal fracture risk, whereas a sparse trabecular pattern indicates osteopenia and high fracture risk. The bone turnover rate in the mandible is twice that of the maxilla, and may, hypothetically, play a role in the development of osteonecrosis of the jaw (ONJ), which has been found mainly in the mandibular alveolar process?