Olaf Krogstad

Periodontal status of mandibular incisors following excessive proclination A study in adults with surgically treated mandibular prognathism

The present study was undertaken to examine whether excessive proclination of mandibular incisors results in gingival retraction. In patients with surgically treated mandibular prognathism, 29 with more than 10 degrees proclination of mandibular incisors and 33 with minimal change in incisor inclination during presurgical orthodontic phase were selected. A total of 21 and 19 patients, respectively, could meet for a clinical follow-up examination including Visible Plaque Index, Gingival Bleeding Index, probing pocket depth, and length of supracrestal connective tissue attachment. Study models and intraoral color slides were also made. The mean postoperative times at this examination were 7.8 (SD 2.5) and 8.1 (SD 2.8) years, respectively. Clinical crown height was measured on the study models taken before and after appliance therapy, at the 3-year postoperative control (check) and at the follow-up examination. The number of teeth with recession was determined from the color slides taken at the same intervals; the thickness of the symphysis was measured on the cephalograms taken before treatment. The results demonstrated significantly more increase in clinical crown height and significantly more teeth developing recession both during appliance therapy and during the period from removal of appliance to the 3-year postoperative control in the patients with excessive proclination than in the patients with minimal change in incisor inclination. The correlation coefficient between width of symphysis and increase in clinical crown height in patients with excessive proclination was statistically significant. Only minimal changes were observed from 3 years postoperatively to the follow-up examination. No differences in clinical measurements were observed between the groups and bone dehiscences were not found.

Craniofacial structure and soft tissue profile in patients with severe hypodontia.

This study compares craniofacial structure and soft tissue profile in persons with mild hypodontia (group I: 2 to 5 congenitally missing teeth, n = 43), moderate hypodontia (group II: 6 to 9 congenitally missing teeth, n = 15) and severe hypodontia (group III: 10 or more congenitally missing teeth, n = 29) with the structure of persons without hypodontia and with normal occlusion (n = 50). The mean age was about 12 years. In group I, the lower second premolars were the most frequently missing teeth, followed by the upper second premolars and the upper lateral incisors. The relative prevalence of missing second premolars decreased with increasing severity of hypodontia. No consistent pattern could be observed when more than five teeth were missing, indicating a different genetic mechanism than for mild hypodontia. A significant retroclination of the incisors and an increased interincisal angle were observed with increasing severity of hypodontia. This was accompanied by a reduction of lip protrusion, being most evident for the upper lip. Increasing numbers of missing teeth resulted also in a decrease in the mandibular plane angle and a reduction in the anterior lower facial height. Few differences in the skeletal parameters were observed. It was concluded that the typical dentofacial structure in persons with advanced hypodontia may be due to dental and functional compensation rather than to a different growth pattern.

Factors influencing the predictability of soft tissue profile changes following mandibular setback surgery.

The objective of this cephalometric study was to assess long-term changes in the soft tissue profile following mandibular setback surgery and investigate the presence of factors that may influence the soft tissue response to skeletal repositioning. The subjects enrolled were 80 consecutive mandibular prognathism patients operated with bilateral sagittal split osteotomy and rigid fixation. Lateral cephalograms were taken at 6 occasions: immediate presurgical, immediate postsurgical, 2 and 6 months postsurgical, and 1 and 3 years postsurgical. The subjects were grouped according to gender and magnitude of setback. Ratios of soft tissue to hard tissue movements were calculated for the subgroups. Females generally demonstrated greater ratios than males with a statistically significant difference for the upper lip and chin (P < .05). Postsurgical alterations in the profiles were more predictable in patients with larger setbacks compared to patients with smaller ones. Skeletal relapse had a profound influence on long-term profile changes. Based on these findings, it is proposed that the database used in prediction software be adjusted to account for such factors in an attempt to improve the accuracy of computerized treatment simulations.

The effect of a partial bite raising splint on the occlusal face height An x-ray cephalometric study in human adults

20 patients (18 - 50 years) with pathological attrition of upper and/or lower anterior teeth were treated, as a temporary measure, by means of a partial chrome-cobalt splint covering the palatal surfaces of the six upper front teeth. Tantalum implants to provide reference points were placed in the basal portion of upper and lower jaw bones. Lateral cephalometric radiographs were taken with and without the splint at the beginning of treatment and thereafter every two months till the difference between measurements was as small as possible. Changes in the occlusal face height were evaluated. Measurement reliability proved to be very high. Continuous use of the splint caused intrusion of the front teeth and eruption of the others in all patients. The intrusion was on an average 1.05 mm and the eruption 1.47 mm after 6 - 14 months, indicating a possible potential for tooth eruption in human adults. More eruption than intrusion appeared to take place in the youngest age groups. Sexual differences could not be established. Use of the splint did not cause the common symptoms of mandibular dysfunction. Lisping was the most serious complaint.

Stability of mandibular incisors following excessive proclination: a study in adults with surgically treated mandibular prognathism.

The purpose of this study was to determine if mandibular incisors could be proclined markedly without increasing the potential for relapse of crowding. Patients with surgically treated mandibular prognathism were selected. In 29 patients the mandibular incisors were proclined more than 10 degrees during the presurgical orthodontic phase. The remaining 33 patients had only minimal change in incisor inclination. A long-term follow-up examination was performed 10.0 (SD 2.3) and 11.1 (SD 3.1) years postoperatively in 26 and 24 patients, respectively. Study casts were measured before and after treatment, three years after surgery, and long-term. Cephalograms were evaluated before and after treatment, immediately before and after surgery, and three years after surgery. Prior to therapy the patients treated with presurgical proclination had less dental arch length and more retroclined and crowded mandibular incisors than the patients in the other group. No differences in parameters were observed at later intervals. Dental arch length and intercanine width decreased and incisor irregularity increased in both groups during the follow-up periods. No intergroup differences in changes were observed. Indications for proclination of mandibular incisors are discussed.

The Effect of a Partial Bite-Raising Splint on the Inclination of Upper and Lower Front Teeth

In a previous paper it was maintained that the effect of the permanent use of an anterior partial bite-raising splint was an intrusion of the front teeth and an eruption of the others. However, the effect might have been merely a change in the inclination of the front teeth. The present study comprised the same material as earlier. Linear and angular changes in the position of upper and lower incisors were measured on cephalometric radiographs. In the upper jaw a possible average proclination occurred, whereas in the lower jaw no or only a very small retroclination took place. The values were well within the method error, and it was concluded that the effect of the splint had been one of intrusion of the upper and lower front teeth and not merely a change in their inclination.

Obstructive sleep apnea: a canonical correlation of cephalometric and selected demographic variables in obese and nonobese patients.

One hundred male obstructive sleep apnea (OSA) patients were classified into 2 groups on the basis of body mass index (BMI): 43 nonobese (BMI < 30 kg/m2) and 57 obese (BMI > or = 30 kg/m2) patients. A comprehensive cephalometric analysis with a multivariate statistical method was performed in order to define the different principal components (PCs) of cervico-craniofacial skeletal and upper airway soft tissue morphology in each group and how they contributed to selected elements of the patient demographic data, ie, apnea-hypopnea index (AHI), nocturnal oxyhemoglobin saturation, and BMI. Thirty cephalometric variables of cervico-craniofacial skeletal morphology were reduced to 8 PCs describing 84.4% and 85.4% of the total variance in obese and nonobese OSA patients, respectively. Sixteen cephalometric variables of hyoid bone position and head posture were reduced to 4 PCs describing 84.4% and 85.9% of the total variance in obese and nonobese OSA patients, respectively. Twenty cephalometric variables of upper airway soft tissue morphology were reduced to 7 PCs describing 89.5% and 84.6% of the total variance in obese and nonobese OSA patients, respectively. For further analysis of PCs, a stepwise multiple regression analysis was chosen. Two dependent variables of interest are the minimal distance of the posterior pharyngeal airway space (PASmin) and AHI. PASmin accounted for 95.3% (obese OSA group) and 74.3% (nonobese OSA group) with 7 PCs and AHI for 46% with 3 PCs in both groups. Three canonical variables and their correspondents with different loadings were established differently for both OSA groups. A canonical correlation successfully clarified the complexity of simultaneous relationship of the relevant variables. These analyses are proved useful to demonstrate the relationship of cervico-craniofacial skeletal and upper airway soft tissue morphology and selected demographic data. This lays down a basis for understanding the complicated pathogenic components of obese and nonobese OSA patients.

Morphology and growth in convex profile facial patterns: a longitudinal study.

Two groups of females, one with normal anteroposterior jaw-base relationships and the other with distal jaw-base relationships, were selected at age 6 and compared longitudinally up to age 18. The purposes of this study were, first, to reveal morphological factors that caused or contributed to a distal jaw-base relationship, and second, to compare growth in the two groups. A distal jaw-base relationship is not a morphological entity caused by some specific aberration in the cranial base or jaws. Rather, it is the result of a combination of predisposing deviations with varying degrees of gravity. A short mandibular corpus and a large MP-SN angle were the only deviations with significant group differences. Distal jaw-base relationships generally worsened with age as compared with normal anteroposterior jaw-base relationships. Inadequate increase in mandibular corpus length in the 6- to 12-year period contributed to the worsening, as did the mandible growing more vertically than normal after age 12.

Correspondence of Cephalometric Values. A Methodologic Study Using Duplicating Films of Lateral Head Plates

Abstract No Abstract Available. From the Dental Institute of Experimental Research and the Department of Orthodontics, Dental Faculty, University of Oslo, Norway.